Investigation of Deterioration Mechanisms of Cellulose Acetate Compounded with Triphenyl Phosphate

Item Type text; Electronic Dissertation

Authors McGath, Molly Kathleen

Publisher The University of Arizona.

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Link to Item http://hdl.handle.net/10150/265818

INVESTIGATION OF DETERIORATION MECHANISMS OF CELLULOSE ACETATE COMPOUNDED WITH TRIPHENYL PHOSPHATE By

Molly Kathleen McGath

______

A Dissertation Submitted to the Faculty of the

DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING

In Partial Fulfillment of the Requirements For the Degree of

DOCTOR OF PHILOSOPHY

In the Graduate College

THE UNIVERSITY OF ARIZONA

2012

THE UNIVERSITY OF ARIZONA

GRADUATE COLLEGE

As members of the Dissertation Committee, we certify that we have read the dissertation prepared by Molly McGath entitled Investigation of Deterioration Mechanisms of Cellulose Acetate Compounded with Triphenyl Phosphate and recommend that it be accepted as fulfilling the dissertation requirement for the

Degree of Doctor of Philosophy

______Date: Nancy Odegaard

______Date: Srini Raghavan

______Date: Barrett G. Potter

______Date: Richard Glass

______Date: Odile Madden

Final approval and acceptance of this dissertation is contingent upon the candidate’s submission of the final copies of the dissertation to the Graduate College.

I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement.

______Date: Dissertation Director: Nancy Odegaard

STATEMENT BY AUTHOR

This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.

Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the copyright holder.

SIGNED: Molly McGath

ACKNOWLEDGEMENTS

There are so very many people to thank for production of this work. I hope that I can do them justice, but I doubt that my words can convey how truly grateful I am for all of their work, prayers and support. Without the prayers I know I would never have finished. First and foremost I need to thank my family, especially my parents David and Marian for being so very supportive of me throughout my education and work. They have been there to help me make decisions and have provided me with a safe-haven and a place that is always called home, especially for little things like tax receipts as I began to bounce around the country and then the globe during my work with heritage conservation science and materials science and engineering.

Thank you Matt and Ally for accompanying me on my trek across country to begin this work at the Smithsonian and for your love and support. Thank you Andrea and Jim for your moral support of and tax guidance for the poor graduate student. And to my grandparents: David H. and Margaret Mary McGath, thank you for believing in this and me; Robert F. and Joan

McCauley your lives inspired mine.

I want to thank my advisor Nancy Odegaard, for being a mentor and sounding board as I have found my way into the field of conservation science. Thank you Odile Madden, for involving me in such an interesting and fantastic project, and for finding means and ways for me to do this research, The Age of Plastic is now! Thank you to my committee members: Richard

Glass, Srini Raghavan and B.G. Potter, for giving me great feedback and for being up to working with me on this project from the opposite side of the country.

I have had the opportunity to work with so many inspiring and innovative people. Thank you, Pamela Vandiver for introducing me into the world of conservation science. Thank you

Mary Striegel and Jason Church of the National Center for Preservation Technology and

Training, I began so much of this path with you. Thank you Blythe McCarthy for bringing me to

Washington, DC for the first time, it was a trip that brought many more. I look forward to beginning my post-doctoral work with you this fall. Thank you everyone at the Arizona State

Museum, you began my experiences in working with museums. Thank you, Lawrence Marcus and Fenella France for your mentorship at the Library of Congress. Thank you fellow engineers of the Thomas G. Chapman Scholarship and Fellowship Committee, that fellowship allowed me to do so very many things that would never have been possible without it. Your mentorship and the legacy of Thomas Chapman mean so very much to me. I want to thank the staff, fellows and interns of MCI for being there to help me with my research. I especially want to thank Robert

Koestler and Paula DePriest for funding my internship and fellowship and for being my academic coaches on the East Coast.

I want to thank Ashley Rose Head for her help in editing and coaching me through the writing process, thank God you and Jeff moved to the east coast in February. Thank you, John and Kathy Opitz, the “something removed” cousins who took me into their home over and over again and are truly my family on this coast. And for all my good friends, notably my close friends Michele Wise, Sarah Weigel, Jackie Reed, Sarah Rasmussen Anderson, Spencer

Anthony, Becky Jacobson, Emilly Phillips and Joe Ptak for helping me stay sane (yet still geeky) throughout the classes, the research and the writing experience. Thank you, Brunella Santerelli and Christina Bisulca (and Odile again) for every work and wine session, for every research planning session and for your company on the journey through the MSE-HCS graduate program at Arizona. Laura, Joe, Ashling and Liam Whelan, you were my family in Arizona and will be my family ever after.

I have been so very lucky in having so many fantastic teachers and mentors that I don’t have room to mention each and every one here. Thank you to the faculty of Mercy High School, the Chemistry, Art History and History Departments of the University of Nebraska, the

Chemistry and Biochemistry Department and the Materials Science and Engineering Department of the University of Arizona. Thank you Mrs. Coate for inspiring me to work in the sciences and showing me that you can overcome all odds to do so. Thank you Mrs. Wells for fostering my love of history. Thank you, David Berkowitz for first mentoring me in research at the University of Nebraska. Go Huskers! Thank you, Hamish Christie for fostering my love of organic chemistry and for helping me to find my path to Materials Science and Engineering and easing my transition from Chemistry. Thank you, Steve Brown and Ann Padias for continuing to give me the opportunity to teach even after I transferred from the Chemistry department. Thank you,

Joseph Simmons for helping me in my transition into the MSE department. Thank you Lori

Boyd and Elsa Morales for a million small and important things, for all the paperwork I wouldn’t have navigated without both of you and for your cheerful smiles every time I see you. Thank you to my fellow faculty and staff at Pima Community College, every day of working with you was a joy. To Jessica Johnson and the entire group working at the Iraqi Institute for the Conservation of

Antiquities and Heritage, my first out of country experiences were amazing. Finally, I need to thank all of my students in Lincoln, Nebraska; Tucson, Arizona; and Erbil, Iraq, I’ve learned far more from you than I ever could have taught.

TABLE OF CONTENTS

TABLE OF CONTENTS ...... 7 LIST OF FIGURES ...... 9 LIST OF TABLES ...... 18 ABSTRACT ...... 19 1. INTRODUCTION ...... 20 2. BACKGROUND ...... 22 Cellulose Acetate “Plastics” ...... 22 Degradation of Cellulose Acetate ...... 29 Degradation with TPP ...... 29 Triphenyl Phosphate ...... 30 Raman Theory ...... 31 Background Bibliography ...... 38 3. METHODS ...... 43 Chemicals-standards: ...... 43 Samples – reagent mixtures: ...... 43 pH Measurement: ...... 46 Raman Spectroscopy: ...... 46 Methods Bibliography ...... 47 4. RESULTS ...... 48 Interpreting the spectrum of TPP ...... 48 Logic of Model Systems ...... 52 Raman of Model Systems ...... 54 Determination of the Mechanism of Deterioration-Recrystallization ...... 57 pH Measurements: Consideration of a Competing Theory ...... 59 Summary ...... 60 Results Bibliography ...... 61 5. DISCUSSION ...... 62 Characterizing the Spectrum of Triphenyl Phosphate ...... 62 Investigation of the Process of Deterioration of CA-TPP Composites ...... 63 Triphenyl Phosphate Recrystallization ...... 65 Evaluating the Possibility of Diphenyl Phosphate Generation from Triphenyl Phosphate ..... 66 Discussion Bibliography...... 67 6. CONCLUSIONS ...... 68 Conclusion Bibliography: ...... 69 7. CASE STUDY: AIRCRAFT RECOGNITION MODELS ...... 70 Background ...... 74 Methods ...... 77 Objects – Aircraft Recognition Models ...... 77 Samples – Aircraft Recognition model fragments ...... 80 X-Ray Fluorescence Spectroscopy: ...... 80

TABLE OF CONTENTS-Continued

SEM-EDX:...... 81 Raman Spectroscopy ...... 81 Results ...... 82 X-ray Fluorescence Spectroscopy ...... 82 Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy ...... 84 Discussion ...... 99 Case Study Bibliography ...... 101 APPENDIX A. CHEMICALS...... 102 APPENDIX B. XRF...... 106 APPENDIX C. RAMAN SPECTROSCOPY ...... 175 Observing instrumental shift for dispersive Raman spectroscopy unit ...... 179 Chemical Spectra: Mixture TPP with Solvent 20:80 w/w % ...... 229 Chemical Spectra: Analysis of Aircraft Recognition Model Residue...... 268 Chemical Spectra: Recrystallization of TPP in Solvents ...... 271 Chemical Spectra: Identifying the bond responsible for a peak between 750-700cm-1 ...... 296 APPENDIX D. SCANNING ELECTRON MICROSCOPY AND ENERGY DISPERSIVE X- RAY SPECTROSCOPY ...... 315 REFERENCES ...... 318

LIST OF FIGURES

Figure 2.1: A: Cellulose, highlighting the monomer unit of D-glucose, B: Cellulose nitrate, C: Cellulose Acetate ...... 24 Figure 2.2: Cellulose (dissolved in acetic acid) reacts with acetic anhydride in the presence of sulfuric acid to form cellulose triacetate ...... 25 Figure 2.1 Stokes, Rayleigh, and Anti-Stokes Scattering, Absorbance and Fluorescence ...... 32 Figure 2.2: Spectroscopic set-up for Raman Spectroscopy ...... 34 Figure 2.3: Monochromatic light hits the sample and is mostly unchanged...... 35 Figure 2.4: Generating a Raman Spectrum ...... 36 Figure 4.1 The peaks observed for TPP, both with and without CA. From top to bottom Raman spectra of: Coupon #14, Coupon #26, Coupon 9, TPP, and DPP, taken by Anthony Maoirana. . 49 Figure 4.2 Structures of the chemicals analyzed by Raman spectroscopy...... 51 Figure 4.3: Proposed first step of a nucleophilic mechanism ...... 52 Figure 4.4: Proposed coordination complex of TPP and CA ...... 53 Figure 4.5: Spectra of TPP, TPP+Amyl Acetate, Amyl Acetate ...... 55 Figure 4.6 Left: Lumarith® Coupon #14, from Salesman’s kit (spectra taken by Anthony Maiorana) of top to bottom: undegraded, degrading and degraded areas. Right: TPP in acetone (spectra taken by Molly McGath) of top to bottom: fully solvated, partially recrystallized and fully recrystallized TPP...... 57 Figure 4.7 Spectra taken on an Almega XR Dispersive Raman spectrometer at 780nm. The blue spectrum is of the liquid TPP, the red spectrum is of the solid TPP...... 58 Figure 4.8: Accelerated aging of TPP time vs pH done to replicate Shinagawa’s experiment. .... 60 Figure 7.1: Aircraft Recognition Models (ARMs) on Display at the National Air and Space Museum (NASM), Washington D.C. Close up pictures of two models on the wall, and one that fragmented upon removal...... 70 Figure 7.2: Models shrink, warp, crack and pieces fall from them to the floor...... 71 Figure 7.3: Fragments of models litter the cases at NASM prior to removal of the exhibit. (Photograph used courtesy of Odile Madden)...... 72 Figure 7.4 Paul E. Garber with target kite. (Source: Smithsonian National Air and Space Museum) ...... 74 Figure 7.5: XRF Spectrum of aircraft recognition model with the original Cruver catalogue number 1944-30. This spectrum shows the presence of phosphorus. This spectrum was taken of this model at the nose of the fuselage of the plane using a Bruker Artax X-ray Fluorescence Spectrometer. (Spectrum taken with Dawn Planas)...... 83 Figure 7.6 Left: USArmy-48 engine break Right: USArmy-48 tail fuselage.pdf ...... 84 Figure 7.7: Concoidal fracture patterns are visually apparent in this fragment with dimensions of 2.3cm x 1cm ...... 86 Figure 7.8 Concoidal fracture pattern from a fragment of an Aircraft Recognition Model, number 1944-31. This secondary electron image was taken at a magnification of 650x, at a voltage of 15.0kV, with a working distance of 11.1 mm...... 87

LIST OF FIGURES-Continued

Figure 7.9: SEM-EDX images of aircraft recognition model fragments. Magnification 40x, Working Distance 12.0mm, kV: 10.0. A: Secondary Electron image of a fragment of an aircraft recognition model. B: Elemental Map of fragment with oxygen, carbon phosphorus and aluminum (from the stud) ...... 88 Figure 7.10: A: multi-element overlay map B: carbon elemental map C: phosphorus elemental map D: oxygen elemental map E: magnesium elemental map F: chlorine elemental map G: calcium elemental map ...... 90 Figure 7.11: Images taken at magnification of 800x, 15.0KV and working distance of 12.7mm A: carbon map of an area of a fragment taken from an ARM, B: phosphorus map of an area of fragment, the red circles highlight areas of high carbon content and phosphorus absence...... 92 Figure 7.12 Magnification 2300x, voltage 15.0kV, working distance 11.4mm. A: SEM secondary electron image B: SEM-EDX elemental map overlay of phosphorus, carbon and oxygen. In the center of these images appears a nucleation point around which phosphorus rich material is recrystallizing...... 93 Figure 7.13: Magnification 2300x, voltage 15.0kV, working distance 11.4mm. A: carbon elemental map, B: phosphorus elemental map, C: magnesium elemental map, D: calcium elemental map ...... 93 Figure 7.14 Magnification: 950x, HV15kV, working distance 10.5. SEM-EDX images taken of a fragment from an aircraft recognition model after it had been soaked in toluene for a month. A: secondary electron image, B: carbon elemental map, C: phosphorus elemental map...... 94 Figure 7.15 Left: Spectra of TPP (standard) and extract from ARM. Comparison between standard TPP spectrum (top) and extracted sample from unnattributed fragment (bottom). Top spectrum taken from library of standards done on an FT-Raman system with an IR-excitation laser. Bottom spectrum taken using 780nm excitation laser on an Almega XR Dispersive Raman Spectrometer using a 10x optic on a microscope attachment of dried extract on a glass microscope slide. Right: photograph of recrystallized extract ...... 95 Figure 7.16 Top: Diethyl phthalate (DEP), Middle: mixture of TPP and DEP extracted with ethyl acetate from ARM fragment after toluene extraction, Bottom: Triphenyl phosphate (DEP) ...... 96 Figure 7.17 Labeled spectrum of ARM extract. DEP is diethyl phthalate, TPP is triphenyl phosphate and TPP + DEP peaks are those that are due to overlaps in both spectra...... 97 Figure 7. 18 Blue: Dimethyl phthalate standard, Red: residue extracted from ARM fragment after toluene extraction, Pink: Diethyl phthalate standard ...... 98 Figure B.1 1944-30 fuselage nose paint ...... 110 Figure B.2 1944-30 fuselage paint ...... 111 Figure B.3 1944-30 wingtip paint ...... 112 Figure B.4 1944-31 ...... 113 Figure B.5 1944-31 engine surface paint ...... 114 Figure B.6 1944-31 wing join ...... 115 Figure B.7 1948-85 fuselage nose ...... 116 Figure B.8 1948-85 tail underside ...... 117 Figure B.9 1948-85 wing depression ...... 118 Figure B.10 1948-85 wing underside ...... 119

LIST OF FIGURES-Continued

Figure B.11 1948-85 wing underside proper right...... 120 Figure B.12 1953-32 fuselage nose...... 121 Figure B.13 1953-35 tail underside...... 122 Figure B.14 1953-32 wing underside ...... 123 Figure B.15 Deaccessioned Object-172 fuselage ...... 124 Figure B.16 Deaccessioned Object-172 tail underside ...... 125 Figure B.17 Deaccessioned Object-172 wing topside ...... 126 Figure B.18 Deacc Object-172 wing topside...... 127 Figure B.19 Deacc Object-172 wing underside ...... 128 Figure B.20 German-30 wing break ...... 129 Figure B.21 German-30 wing top side ...... 130 Figure B.22 German-30 wing topside white stuff ...... 131 Figure B.23 German-30 wing under side ...... 132 Figure B.24 Great Britian-21 engine break ...... 133 Figure B.25 Great Britian-21 engine side ...... 134 Figure B.26 Great Britian-21 engine tip ...... 135 Figure B.27 Great Britian-24 wing break ...... 136 Figure B.28 Great Britian-24 wing topside ...... 137 Figure B.29 Great Britian-24 wing underside ...... 138 Figure B.30 Japan-30 interior fuselage ...... 139 Figure B.31 Japan-30 wing join ...... 140 Figure B.32 Japan-30 wing surface paint ...... 141 Figure B.33 Japan-30 wing surface paint top ...... 142 Figure B.34 Russia-3 fuselage nose ...... 143 Figure B.35 Russia-3 tail underside ...... 144 Figure B.36 Russia-3 wing underside ...... 145 Figure B.37 Unknown1- Fragment A ...... 146 Figure B.38 Unknown1 fuselage exterior ...... 147 Figure B.39 Unknown1 fuselage interior ...... 148 Figure B.40 Unknown 1 tail underside ...... 149 Figure B.41 Unknown 1 wing join ...... 150 Figure B.42 Unknown 1 wing underside...... 151 Figure B.43 Unknown 2 wing cracked side ...... 152 Figure B.44 Unknown 2 wing cracked side gloss ...... 153 Figure B.45 Unknown 2 wing without crack ...... 154 Figure B.46 Unknown 2 wing without crack 2...... 155 Figure B.47 Unknown 2 wing join ...... 156 Figure B.48 Unknown 3 wing join ...... 157 Figure B.49 Unknown 3 wing underside...... 158 Figure B.50 Unknown 3 wing underside 2 ...... 159 Figure B.51 US-49 wing join ...... 160

LIST OF FIGURES-Continued

Figure B.52 US-49 wing strut ...... 161 Figure B.53 US-49 wing top side ...... 162 Figure B.54 US-49 wing underside...... 163 Figure B.55 USArmy-31 engine ...... 164 Figure B.56 USArmy-31 engine 2 ...... 165 Figure B.57 USArmy-48 engine break ...... 166 Figure B.58 USArmy-48 tail fuselage ...... 167 Figure B.59 USArmy-48 tail underside 1 ...... 168 Figure B.60 USNavy-12 fragment ...... 169 Figure B.61 USNavy-12 long fragment ...... 170 Figure B.62 USNavy-12 long fragment broken edge ...... 171 Figure B.63 USNavy-14 fuselage ...... 172 Figure B.64 USNavy-14 tail break ...... 173 Figure B.65 USNavy-14 tail underside ...... 174 Figure C.1 Acetaldehyde 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 182 Figure C.2 Acetaldehyde 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 182 Figure C.3 Acetic Acid 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 184 Figure C.4 Acetic Acid 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 185 Figure C.5 Acetone 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. . 188 Figure C.6 Acetone 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer. ... 189 Figure C.7 Acetonitrile 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 191 Figure C.8 Acetonitrile 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer ...... 192 Figure C.9 Amyl Acetate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 195 Figure C.10 Amyl acetate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 196 Figure C.11 Cellulose 1300-100 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 198 Figure C.12 Cellulose acetate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 201 Figure C.13 Cellulose acetate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 202 Figure C.14 Diethyl phthalate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 205

LIST OF FIGURES-Continued

Figure C.15 Diethyl phthalate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 205 Figure C.16 Diethyl phthalate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 206 Figure C.17 Ethyl Acetate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 209 Figure C.18 Ethyl acetate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 210 Figure C.19 Ethyl Ether 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 213 Figure C.20 Ethyl ether 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 214 Figure C.21 Formaldehyde 37% 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 217 Figure C.22 Formaldehyde 37% 1300-150cm-1, taken with Almega XR Dispersive Raman spectrometer...... 218 Figure C.23 Formamide 1300-150cm-1, taken with Almega XR Dispersive Raman spectrometer...... 221 Figure C.24 Formamide 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 222 Figure C.25 d-Glucose 1300-100cm-1, taken with Almega XR Dispersive Raman spectrometer...... 225 Figure C.26 d-Glucose 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 226 Figure C.27 Triphenyl phosphate in acetaldehyde 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer ...... 230 Figure C.28 Triphenyl phosphate in acetaldehyde 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 230 Figure C.29 Triphenyl phosphate in acetic acid 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 232 Figure C.30 Triphenyl phosphate in acetic acid 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 233 Figure C.31 Triphenyl phosphate in acetone 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 236 Figure C.32 Triphenyl phosphate in acetone 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 236 Figure C.33 Triphenyl phosphate in acetonitrile 4000-400cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 239 Figure C.34 Triphenyl phosphate in acetonitrile 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 239

LIST OF FIGURES-Continued

Figure C.35 Triphenyl phosphate in amyl acetate 4000-400cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 241 Figure C.36 Triphenyl phosphate in amyl acetate 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 242 Figure C.37 Triphenyl phosphate in diethyl ether 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 244 Figure C.38 Triphenyl phosphate in diethyl ether 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 245 Figure C.39 Triphenyl phosphate in diethyl phthalate 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 247 Figure C.40 Triphenyl phosphate in diethyl phthalate 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 248 Figure C.41 Triphenyl phosphate in ethyl acetate 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 250 Figure C.42 Triphenyl phosphate in ethyl acetate 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 251 Figure C.43 Triphenyl phosphate in 2-propanol 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 254 Figure C.44 Triphenyl phosphate in 2-propanol 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 255 Figure C.45 Triphenyl phosphate in toluene 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 257 Figure C.46 Triphenyl phosphate in toluene 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 257 Figure C.47 Triphenyl phosphate in trichloroethylene 4000-400 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 259 Figure C.48 Triphenyl phosphate in trichloroethylene 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 260 Figure C.49 Triphenyl phosphate (liquid) 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 262 Figure C.50 Triphenyl phosphate (liquid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 263 Figure C.51 Triphenyl phosphate (solid) 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 265 Figure C.52 Triphenyl phosphate (solid) 900-600 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 266 Figure C.53 Top: Diethyl phthalate standard, Middle: Aircraft recognition model residue after ethyl acetate has been evaporated, Bottom: Triphenyl phosphate, taken with Almega XR Dispersive Raman spectrometer, 3500-150 cm-1...... 268

LIST OF FIGURES-Continued

Figure C.54 Comparison between Blue: Dimethyl phthalate, Red: Aircraft recognition model residue and Pink: diethyl phthalate, 1250-720cm-1, Taken with Almega XR Dispersive Raman spectrometer...... 269 Figure C.55 Identification of all the contribution of the peaks seen in the residue removed from the aircraft recognition models, 3500-150 cm-1 Taken with Almega XR Dispersive Raman spectrometer...... 270 Figure C.56 TPP recrystallized in acetone spot 1 (solution) 1300-100 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 272 Figure C.57 TPP recrystallized in acetone spot 1 (solution) 750-700 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 273 Figure C.58 TPP recrystallized in acetone spot 2 (solid) 1300-100 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 274 Figure C.59 TPP recrystallized in acetone spot 2 liquid solidifying 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 275 Figure C.60 TPP recrystallized in acetone spot 3 (solid) 1300-100 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 276 Figure C.61 TPP recrystallized in acetone spot 3 (solid) 750-700 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 277 Figure C.62 TPP recrystallized in acetone spot 4 (solid) 1300-100 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 278 Figure C.63 TPP recrystallized in acetone spot 4 (solid) 750-700 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 279 Figure C.64 TPP recrystallized in acetone spot 5 (solid) 1300-100 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 280 Figure C.65 TPP recrystallized in acetone spot 5 (solid) 750-700 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 281 Figure C.66 TPP recrystallized in acetone spot 6 (solid) 1300-100 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 282 Figure C.67 TPP recrystallized in acetone spot 6 (solid) 750-700 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 283 Figure C.68 TPP recrystallized in acetonitrile spot 2 (partial crystallization) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 284 Figure C.69 TPP recrystallized in hexanes (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 285 Figure C.70 TPP recrystallized in hexanes (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 286 Figure C.71 TPP recrystallized in 2-propanol spot 1 (solution) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 287 Figure C.72 TPP recrystallized in 2-propanol spot 1 (solution) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 288

LIST OF FIGURES-Continued

Figure C.73 TPP recrystallized in 2-propanol spot 2 (mostly crystallized) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 289 Figure C.74 TPP recrystallized in 2-propanol spot 2 (mostly crystallized) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 290 Figure C.75 TPP recrystallized in 2-propanol spot 3 (mostly crystallized) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 291 Figure C.76 TPP recrystallized in 2-propanol spot 3 (mostly crystallized) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 292 Figure C.77 Comparison of two time points:TPP recrystallized in 2-propanol spot 2 (solution phase) and 3 (mostly crystallized) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 293 Figure C.78 TPP recrystallized in toluene (solution phase) 1300-100 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 294 Figure C.79 TPP recrystallized in toluene (solution phase) 750-700 cm-1, taken with NXR FT- Raman module attached to a 6700 FTIR spectrometer...... 295 Figure C.80 Tributoxyethyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 297 Figure C.81 Tributoxyethyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 298 Figure C.82 Tributyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 299 Figure C.83 Tributyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 300 Figure C.84 Tricresyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 301 Figure C.85 Tricresyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 302 Figure C.86 Triethyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 303 Figure C.87 Triethyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 304 Figure C.88 Triethyl phosphite 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 305 Figure C.89 Triethyl phosphite 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 306 Figure C.90 Triethyl phosphine oxide 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 307 Figure C.91 Triethyl phosphine oxide 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 308 Figure C.92 Triphenyl phosphate 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 309

LIST OF FIGURES-Continued

Figure C.93 Triphenyl phosphate 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 310 Figure C.94 Triphenyl phosphite 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 311 Figure C.95 Triphenyl phosphite 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 312 Figure C.96 Triphenyl phosphine oxide 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 313 Figure C.97 Triphenyl phosphine oxide 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 314 Figure D.1 SEM-EDX, Aircraft recognition model fragment, uncoated. Magnification 1900x, HV 10.0kV, working distance 12.8mm. Carbon in green, phosphorus in purple...... 315 Figure D.2 SEM-EDX, Aircraft recognition model fragment, uncoated. Magnification 320x, HV 10.0kV, working distance 11.5mm. Carbon in green, phosphorus in purple...... 315 Figure D.3 SEM-EDX Triphenyl phosphate recrystallized in acetonitrile, mounted on carbon sticker, uncoated. Magnification 23x, HV 10.0kV, working distance 11.5mm...... 316 Figure D.4 SEM, Aircraft recognition model fragment after extraction in toluene. Magnification 30x, HV 10kV, working distance 10.5mm. Backscatter electron mode...... 316 Figure D.5 SEM, Aircraft recognition model fragment after toluene extraction. Left left, secondary electron mode. Right EDX image, Silicon-green and phosphorus-purple overlay. .. 316 Figure D.6 SEM, Magnification 950x, HV 10.0kV, working distance 10.5mm. Right: secondary electron image, Middle: EDX map of phosphorus, Left: EDX map of carbon ...... 317

LIST OF TABLES

Table 3.1: Mixtures of TPP and Solvent ...... 44 Table 3.2: Recrystallization of Triphenyl Phosphate in Various Solvents...... 45 Table 3.3: Hydrolysis of TPP ...... 46 Table 4.4 Peaks in various chemicals in the range 900-600cm-1...... 50 Table 4.5 TPP:Chemical (20:80% w/w) Peaks Observed and Peak Shifts ...... 56 Table 7.6: Year and Quantity of Collection of Aircraft Recognition Models ...... 78 Table 7.7: List of Planes analyzed by XRF ...... 79 Table B.8: Aircraft Recognition Models: Summary of XRF ...... 106 Table C.9 Measurement of TPP peak by Dispersive Raman ...... 179 Table C.10: Recrystallization of Triphenyl Phosphate in Various Solvents ...... 271 Table D.11: Peaks in various chemicals in the range 900-600cm-1...... 296

ABSTRACT

The mechanisms of the deterioration of cellulose acetate compounded with triphenyl phosphate were investigated. A key peak shift of 726cm-1 to 718cm-1 in the Raman spectrum of triphenyl phosphate (726cm-1 uncompounded) when compounded in cellulose acetate (718cm-1) was tied to the action of C-O bonds in triphenyl phosphate. The molecular bonds responsible for the 726cm-1 peak were identified by collecting and examining spectra of chemicals with functional groups similar to triphenyl phosphate.

Initially it was hypothesized that triphenyl phosphate acts as nucleophilic catalyst of deacetylation. This mechanism was evaluated by dissolving triphenyl phosphate in solvents that served as functional group analogues of cellulose acetate. These liquid-solution systems have a faster rate of reaction and complete mixing with triphenyl phosphate compared with what is seen in cellulose acetate solid-solution systems. The results of the cellulose acetate analogue experiments did not support the hypothesis of triphenyl phosphate acting as a nucleophilic catalyst of deacetylation. The results instead support a new theory of deterioration induced by the recrystallization of triphenyl phosphate. Additionally, the prevailing theory of triphenyl phosphate induced deterioration as proposed by Shinagawa et al. in 1992 was reviewed. The experiments conducted here do not support Shinagawa’s theory.

1. INTRODUCTION

The goal of this research was to determine the mechanism by which triphenyl phosphate

(TPP) induces physical breakdown in cellulose acetate (CA) compounded plastics. As was documented by Tsang et al. in 2009, historic injection molded cellulose acetate plastic coupons that contained TPP shrank, fractured, distorted, and broke into pieces over time, while coupons without TPP did not. Three mechanisms were investigated to discern why. Shinagawa et al. in

1992 proposed a mechanism for how TPP induces deterioration in cast CA films like those used in the motion picture industry. Shinagawa proposed that TPP deteriorates into the acidic compound diphenyl phosphate (DPP), which he proposed would cleave acetate groups and the beta1-4 glucose bonds which hold the cellulose acetate backbone chain together. Data from the current study does not support this theory. Two other potential mechanisms are proposed and investigated here. The potential of TPP to act as a nucleophilic catalyst capable of cleaving acetyl groups from CA was postulated but has not been borne out by the experimental data. It appears instead that the extreme fracturing observed in some historic injection molded cellulose acetate plastics is caused by aggregation and crystallization of TPP.

CA compounded with TPP is examined in this study as a material created through human engineering which has failed over time. “The core paradigm of materials science and engineering is that material selection and processing leads to particular structures of artifacts, giving rise to properties that determine artifact performance.” (Kingery 1996:176) The extreme degradation seen in CA compounded with TPP has presented a problem to the collectors of materials made from this item. The mechanism of degradation must be understood before treatment can be done on these objects, as is discussed in the case study covered in the last chapter. The history and

21 context of cellulose acetate as a synthetic plastic and triphenyl phosphate as a plasticizer are discussed in Chapter 2: Background. Experiments were conducted to ascertain why TPP induces the deterioration of cellulose acetate as outlined in Chapter 3: Methods. The results of these experiments are overviewed in Chapter 4: Results, which are then discussed in more detail in

Chapter 5: Discussion. Chapter 6: Conclusions summarizes what was learned from this research.

Kingery, D. 1996. “A Role For Materials Science” Learning from Things, Washington: Smithsonian Institution Press, 175-180.

2. BACKGROUND

Objects made from the materials commonly called plastic are entering into museum collections and their long-term behavior is largely unknown, though deterioration of many of these objects is observed. (Williams 2002, Shashoua 2008) One material class is a so-called malignant plastic, cellulose acetate. (Williams 2002) The focus of this dissertation is the investigation using Raman spectroscopy of the deterioration mechanism of a cellulose acetate plastic containing triphenyl phosphate. The following sections will provide background information on cellulose acetate plastics, triphenyl phosphate and Raman spectroscopy.

Cellulose Acetate “Plastics”

The definition of the word “plastic” changes dependent on the author and context and sometimes the word “plastic” mistakenly is used as a synonym for polymer. (e.g. Calmes 1991, one among many) Here the term plastic will be used synonymously with “compounded polymer” as this term best describes the materials examined. A “compounded polymer” is a polymer to which other chemicals have been added to change the properties of the material. (Mascia 1974)

The base component of a “plastic” and what often gives it its name is the polymer(s) that represents the largest weight percent of the material. (Shashoua 2008) A polymer consists of smaller repeat units or monomers that are bonded covalently to one another, like beads strung together to form a necklace. (McGlinchey 1991) The cellulose molecule is constructed of glucose monomers or beads joined by beta 1-4 linkages. (See Figure 2.1A) (Staudinger 1920,

Charlton 1926, Conaway 1938)

A plastic or a compounded polymer has had chemicals added to the polymer to change its properties. (Shashoua 2008) This means that one “cellulose acetate” plastic is not necessarily the same as another, given the possibility of different additives. (Shashoua 2008)

Cellulose acetate is shown in Figure 2.1C, and like its predecessor cellulose nitrate

Figure 2.1B is a polymer that is made by modifying cellulose Figure 2.1A. Most cellulose acetate is made by reacting cellulose with acetic anhydride, acetic acid and sulfuric acid.

(Steinmeier 2004) Cellulose is a naturally occurring polymer found primarily in plants, (Klemm

2005) and historically the cellulose used for cellulose acetate was most often obtained from cotton linters. (Stannett 1950, Rustemeyer 2004) In cellulose, the repeating glucose units have three alcohols that are form hydrogen bonds with other molecules nearby. These hydrogen bonds produce strong intermolecular bonds which allow these molecules to serve as structural materials. (Klemm 2005)

Cellulose acetate and cellulose nitrate do not have the same ability to hydrogen bond.

This gives these two chemicals different properties from cellulose. The nitrate and acetate functional groups contribute to the greater solubility in organic solvents and greater thermoplasticity when compared with cellulose. The acetate and nitrate groups also give cellulose acetate and cellulose nitrate their lower and greater flammability respectively.

D-glucose unit

Figure 2.1: A: Cellulose, highlighting the monomer unit of D-glucose, B: Cellulose nitrate, C: Cellulose Acetate

The first synthesis of cellulose acetate was conducted in Germany in 1865 in by Paul

Schützenberger. Esterification (called etherification by the authors at the time) of other materials had been previously conducted (Berthelot 1856), but Schützenberger was the first to use acetic anhydride and to characterize the product of the acetylation of cellulose.

(Schützenberger 1865)

Later, the synthesis of cellulose acetate was improved by the addition of catalytic amounts of sulfuric acid (Franchimont 1879) and in 1894 a United States patent using a zinc chloride catalyst was granted to Cross and Bevan (Rustemeyer 2004). Other manufacturing details make up multitudes of patents, which can be useful is discerning the goals of the authors but are often unreliable in detailing the processes used industrially. (Fernández-Villa 2005)

Despite its initial creation in 1865 and the following work done to modify its production, cellulose acetate would not be manufactured on a large scale for decades. This was due: to the insolubility of cellulose triacetate (the only form of cellulose acetate known before 1903) in most common solvents with the exception of some toxic chlorinated solvents, to the need to develop new processing methods for cellulose acetate and the high cost of production using specially cleaned cotton linters and the then expensive acetic acid (the synthetic version had not yet been made available). (Rustemeyer 2004)

Figure 2.2: Cellulose (dissolved in acetic acid) reacts with acetic anhydride in the presence of sulfuric acid to form cellulose triacetate

Cellulose triacetate is the polymeric material in which all three hydroxyl units have been replaced by acetate groups (or >2.7 acetylations per monomer unit). (Zugenmaier 2004)

“Cellulose acetate” often refers to a polymer with something less than this degree of substitution.

(Zugenmaier 2004) Generally this degree of substitution is 2.4 (Zugenmaier 2004) or 2.5 (Puls

2010) which correlates with the cellulose acetate polymer which is soluble in acetone.

The earliest date of mass industrial use was after the discovery of cellulose diacetate by hydrolysis of cellulose triacetate in the US in 1903. (Miles 1903, Eichengrün 1903) This cellulose acetate (cellulose diacetate) was soluble in acetone (Malm 1942) and this solubility really made this material interesting to an industry searching for a replacement material for the

“first plastic” a cellulose nitrate based material. (Sachs 1921, Rustemeyer 2004).

Between 1910 and 1920 a number of companies set up factories in Europe and the United

States with different named versions of cellulose acetate composites. (Rustemeyer 2004, Vaupel

2005) The Bayer Company had a cellulose diacetate material called Cellit®, (Rustemeyer 2004) and a lacquer called Cellon® which was used to paint airplane fabrics. (Vaupel 2005) The

Dreyfus brothers set up shop in 1912 and made Cellonit®. (Rustemeyer 2004) The Celluloid corporation made injection moldable articles of cellulose acetate composites called Lumarith® by 1926. (Tsang 2009)

Cellulose acetate composite materials were developed and replaced cellulose nitrate composites, especially in applications where flammability was an issue. (Carollo 2004) The use of cellulose acetate as photographic film generated multitudes of patents. (Lindsay 1912) Other uses include as artificial silk, (Wagner 1904), imitating natural substances (Lederer 1904,

Lindsay 1912), use as a material in its own right (Lindsay 1912), lacquers (Lederer 1905,

Hofmann 1929), textile fiber in 1918 (Law 2004), airplane fabric dope (Welch 1924, Vaupel

2005, Hofmann 1929), medical splints (Carter 1924), laminated safety glass (Watkins 1933), and safety motion picture film (Fordyce, C.R. 1948), among many others.

The production of cellulose acetate reached a peak usage in 1946 after World War II, dropping slightly in the next few years (Stannett 1950) but over the course of the 20th century production of textile cellulose acetate hit a peak around 1960, and from 1970 to 1980 there was a peak in the use of cellulose acetate for the fields of coatings, films, and molding; and the market has continually increased in the use of cellulose acetate as tow, untwisted bundle of continuous filaments, for cigarette filters. (Rustemeyer 2004)

Cellulose acetate was used for a number of purposes during WWII and this time period saw use of the injection molding in producing cellulose acetate plastics. (Barker 1999) One of the first cellulose acetate molding powder patents in the US dates to 1919 (Shashoua 2008) and

Celluloid company had been making injection molded cellulose acetate since 1926. (Tsang

2009) Unlike cellulose acetate films which could be dissolved in acetone and may have had no additional compound added to them, cellulose acetate molding powders needed to be compounded with plasticizers before being used in injection molding. (Stannett 1950) Cellulose acetate does not melt well without plasticizers (Stannett 1950) and in injection molding the molding powder is melted by heating and then injected under pressure into molds. (McGlinchey

1991) Zugenmaier in 2004 did experiments in which the Tm was measured for cellulose acetate using differential thermal analysis (DTA) at 290°C, and using torsional braid analysis (TBA) at

307°C. These temperatures are significant because the degradation temperature (Td) was measured by Thermal gravimetric analysis (TGA) at 356°C for a cellulose triacetate sample.

(Zugenmaier 2004) Having a Td so close to the Tm means that there is a narrow window (less than 50ºC in this instance) in which one could melt the polymer without degrading it, to minimize degradation due to temperature plasticizers were added to lower the melting temperature. (Stannett 1950, Sully 1962, Olabisi 1997)

Plasticizers were often a large weight percentage component of the plastic that they were added to. (Stannett 1950, Sully 1952) In addition to reducing the Tm of the cellulose acetate, plasticizers changed the performance and properties of the final object. (Zugenmaier 2004)

One well acknowledged and substantiated mechanism of plasticization is that in which plasticizers (and solvents) interfere with the intermolecular bonds that are formed between strands of polymer.(Shtarkman 1983) One of the earliest and most prevalent of plasticizers was camphor, which was the most common plasticizer for cellulose nitrate plastics. (Sachs 1921)

Though cellulose acetate-camphor composites were attempted, the technology for compounding camphor with cellulose acetate systems was not directly transferable from how camphor was compounded within cellulose nitrate systems; these two materials have different interactions with camphor. (Stannett 1950) There was an additional negative aspect to using camphor because camphor increased the flammability of the cellulose acetate plastics. (Sachs 1921)

Flammability was a safety issue with early plastics like celluloid using flammable polymers and plasticizers like cellulose nitrate and camphor. (Sachs 1921) In looking for a replacement material for celluloid a requirement was a lower flammability than that seen with celluloid. (Sachs 1921) Cellulose acetate is more stable to heat than cellulose nitrate, (Evans

1949) however when casting cellulose acetate from solutions, flammable solvents like alcohols or acetone where often used. (Sachs 1921) Most solvents are chosen so that they evaporate out and thus are found at low concentration (if at all) in the final material, where they serve a minor role as plasticizers. (McGlinchey 1991) When plasticized with camphor, cellulose acetate was more flammable than when alone. To solve this problem, manufacturers looked to plasticizer compounds that were less flammable, non-flammable or even fire-retardant. (Sachs 1921)

Triphenyl phosphate is a fire-retardant plasticizer that is still added to flammable plastics and

29 was a major component in many cellulose acetate plastics during the mid-20th century as TPP content often ranged in quantity from 16-30 percent by weight. (Sully 1962, Stannett 1950)

Degradation of Cellulose Acetate

Cellulose acetate breaks down by hydrolysis in the presence of water and releases acetic acid. (Puls 2010) Over time cellulose acetate becomes cellulose as the acetyl groups are cleaved.

(Manley 1963, Williams 2002) This cellulose is subject to acid breakdown of the 1-4 beta glucosidic linkages that make up the chain links of the polymer (Williams 2002) as well as some biological degradation. (Puls 2010) The cleavage of the backbone weakens the overall material.

(Williams 2002) The release of acetic acid as a product of breakdown is apparent in the smell of vinegar, and this is commonly called vinegar syndrome. (Williams 2002) Because acid can catalyze the further degradation of the material a common recommendation is to store cellulose acetate plastics under well-ventilated conditions to remove acid from the object and to isolate these plastics from other objects. (Williams 2002, Conserve-O-Gram 2010) However, artificial aging studies have shown that cellulose acetate alone is often quite stable. (Hill 1936, Shinagawa

1992)

Degradation with TPP

Cellulose acetate compounded with triphenyl phosphate (TPP) has been seen to degrade.

(Shinagawa 1992, Tsang 2009) In 1992 Shinagawa et al. reported that the degradation of cellulose acetate that was seen with triphenyl phosphate in films was due to the generation of diphenyl phosphate (DPP) from triphenyl phosphate in acid. Shinagawa stated that this catastrophically lowered the pH of the cellulose acetate, leading to polymeric chain scission and eventual degradation of the whole material.

A set of Lumarith® coupons was studied at the Museum Conservation Institute (MCI) and triphenyl phosphate was tied to degradation of cellulose acetate, but DPP was not identified in these objects. (Tsang 2009) Tsang’s study showed that in a group of forty-nine cellulose acetate coupons from the early-20th century that three coupons were degrading. The features that united the three degrading coupons were that they were cracked and warped, and that only these three coupons had triphenyl phosphate in them. Triphenyl phosphate was identified using

Raman spectroscopy, and it was noted that there was a peak shift in the spectrum of triphenyl phosphate. A peak occurs at 726cm-1 when TPP is alone. This peak is seen at 718cm-1 when

TPP is found in intact areas of cellulose acetate plastic. In areas where the plastic had degraded the TPP peak is seen again at 726cm-1, and there was evidence of some crystalline material containing TPP in the deteriorated plastic. The peak shift from 726cm-1 to 718cm-1 indicates that there is an interaction between the TPP and the cellulose acetate.

The investigation of what causes this peak shift is discussed further in the Methods,

Results, and Discussion sections.

Triphenyl Phosphate

In 1902, Zühl and Eisemann patented TPP and its sister compounds tricresyl phosphate and trinaphthyl phosphate (whether 1- or 2-napththyl is not stated) as replacement plasticizers for camphor in cellulose nitrate composites. (Zühl 1902). Zühl’s 1902 patent mentions that TPP does not smell and reduces flammability of the plastic and this makes it a better plasticizer than camphor. TPP is listed in many patents after that.

Triphenyl phosphate is a solid plasticizer with a melting point of 48.5°C. (Fordyce, C.R.

1940) TPP was added as a plasticizer for cellulose acetate dope for plane wings and was cited as decreasing the flammability of the cellulose acetate. (Rusch 1919) (Patent for formulation of

31 such a dope (Dreyfus 1920)) However when used in films TPP has been linked to brittleness which is mentioned in an article from 1921. In this article is listed many plasticizers that were used (or at least patented to be used) to replace camphor in cellulose nitrate due to the volatility and unreliable nature of the camphor market. (Sachs 1921) This source provides one with the ability to track the first mentions of triphenyl phosphate, and other chemicals, as a plasticizer.

In a 1931 article it is noted that triphenyl phosphate lost popularity as a plasticizer to its relative tricresyl phosphate (a liquid plasticizer), at least in the field of cellulose nitrate lacquers.

(Symons 1931) This loss of popularity is tied to the fact that TPP is solid and crystalline at room temperature. (Hofmann 1929) However, a few years later a molding powder patent for cellulose acetate suggests TPP as a potential plasticizer. (Dreyfus 1933) By 1962 TPP was used as a co- plasticizer to stabilize the more volatile liquid plasticizers dimethyl and diethyl phthalates. (Sully

1962) In 1959 and again in 1965 TPP is highlighted as a stabilizing plasticizer in cellulose acetate laminates of archival documents. (Wilson 1959, Gear 1965) A crystalline structure for

TPP was determined in 1965 by Svetich after TPP was recrystallized from an ether solution into needle-like crystals. (Svetich 1965) For this research Raman spectroscopy was used to investigate the electronic structure of TPP and how it behaves as in solution.

Raman Theory

Raman spectroscopy can identify TPP in an object or solution directly, this technique can be a non-destructive or non-invasive method and it can be used on samples that are held in glass containers or dissolved in water, as glass and water have little signal in Raman spectroscopy. This section provides an overview of how Raman spectroscopy works and how the technique is used to look at the molecular interactions of TPP.

Raman spectroscopy works by measuring light that is inelastically scattered from a sample. This differs from Infrared (IR) spectroscopy as in IR spectroscopy one is looking at what wavelengths of light were absorbed. Elastically scattered light, called Rayleigh scattering, is reflected, refracted, or transmitted without change in energy as shown in Figure 2.1. However a small fraction of light is inelastically scattered from a sample. Inelastic scattering includes light that has gained energy and has a slightly shorter wavelength than it had prior to encountering an object, or more specifically a bond, and this is known as anti-Stokes scattering.

Inelastic scattering also includes light that has lost energy and has a slightly longer wavelength than it had prior to encountering an object, and this is known as Stokes scattering.

Figure 2.3 Stokes, Rayleigh, and Anti-Stokes Scattering, Absorbance and Fluorescence

Stokes scattering was measured by Raman spectroscopy for this study. Monochromatic light, supplied by a laser, was focused on the sample (see Figure 2.4), and the majority of this light was scattered elastically (Rayleigh scattering). However a small amount of energy from a small number of photons of light is transferred to the sample (Stokes scattering), and a small amount of energy is transferred from the sample to photons of light (Anti-Stokes scattering) (see

Figure 2.3).

Because most of the light that is scattered from a sample retains the same wavelength as the monochromatic light source this must be filtered out before the inelastically scattered light can be observed. The Stokes scattered light is collected by filtering out the Rayleigh scattering, and any higher energy wavelengths (Anti-Stokes scattering) before the light gets to the detector, and the instruments used for this dissertation employed edge filters to accomplish this. The remaining light is picked up by the detector after being separated by wavelength by a diffraction grating and this is converted to a signal that goes to a processor which produces an output in the form of a spectrum.

Figure 2.4: Spectroscopic set-up for Raman Spectroscopy

The energy transferred from the photons of light to the sample is characteristic of the bonds present in the chemicals of the sample, that is to say a C-H bond will take a certain amount of energy and a C=O will take a different amount of energy from the photons. The photons that interact with each of these bonds will have different wavelengths from one another after this interaction. This transferred energy allows for the bond electrons to enter virtual energy states which correlate with the stretching or bending of a polarizable symmetric bond system

(typically). This is in comparison to what occurs when the photons of light are absorbed by the bond and that energy excites the bond into an excitation energy state as measured in IR spectroscopy. Typically what is observed by IR spectroscopy is the stretching or bending of bonds in an asymmetric system or dipole. While this is not a hard and fast rule this distinction of a polarizable symmetric versus a dipole or asymmetric systems is of assistance when considering why water has little observed signal in Raman spectroscopy but such a strong signal as observed

35 in IR spectroscopy and why benzene has a strong signal in Raman spectroscopy but a weak signal in IR spectroscopy.

Figure 2.5: Monochromatic light hits the sample and is mostly unchanged.

Only a small number of photons interact with the sample. Figure 2.5 does not indicate the relative number of photons of these wavelengths; rather it shows the phenomenon of the change in wavelength of photons as they encounter the sample.

A typical Raman spectrum plots the wavenumber of the energy transferred to the sample on the x-axis against the intensity of this signal on the y-axis, which relates to the number of photons with that wavenumber as shown in Figure 2.6.

Generating a Raman Spectrum

Number of photons returningphotonsof Number

Wavenumber difference of returning photons

Figure 2.6: Generating a Raman Spectrum

The movement of a peak from one location to another in the Raman spectrum correlates to a change in the energy of the bond that produces the peak. Thus Raman spectroscopy can be used to detect changes in the electronic environment of the molecule, and this fact sparked the research conducted for this dissertation. Seeing a peak shift in the TPP spectrum from 726cm-1 to 718cm-1 when TPP is compounded with CA indicates that there is a change to the TPP molecule, this is a decrease in the energy and lengthening of the bond producing that peak.

The shift of a peak from a higher wavenumber to a lower wavenumber corresponds to a lower energy transferred to the molecule (thus the energy of the system is lower). A shift from a lower wavenumber to a higher wavenumber corresponds to an increase in the energy transferred to the molecule. Thus seeing a peak shift of eight wavenumbers (726cm-1 to 718cm-1), which is larger than the full width half maximum of the peak of five wavenumbers, in the triphenyl phosphate spectrum indicates that there is a difference in the molecular environment experienced by triphenyl phosphate between intact cellulose acetate-triphenyl phosphate composites and

37 deteriorating cellulose acetate-triphenyl phosphate composites. Investigating what causes this peak shift for triphenyl phosphate provides clues as to what causes the deterioration of the cellulose acetate-triphenyl phosphate composite systems. The Methods Chapter discusses the design of these experiments.

The power of Raman for use in museum collections is due to its nondestructive analytical possibilities, the fact that it may be used for chemical identification rather than the functional group identification that typifies the use of IR spectroscopy, and the fact that samples are analyzable through materials like glass and water.

The intensities of the calculated wavelengths (x-axis values) are related to the initial excitation wavelength of light. Thus as the excitation wavelength of light is changed the intensities (y-axis values) of the calculated wavelengths may change, this is most easily observable when comparing spectra gathered using an excitation laser in the IR-region of the spectrum to an excitation laser in visible light region of the spectrum.

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3. METHODS

This chapter provides the experimental methods of the preparation and analysis of analytical chemical samples and the setup of model systems. The research was conducted at the

Smithsonian Institution’s Museum Conservation Institute (MCI) and the materials and instruments were all provided by MCI.

Chemicals-standards:

All chemicals were used as provided from the manufacturer. Raman spectra were taken of all chemicals in their pure form. The information about these chemicals can be found in the

Appendix.

Samples – reagent mixtures:

Raman spectra were collected of TPP dissolved in solvents in weight percent ratios as shown in Table 3.1. TPP and the solid solvents were weighed out on a Mettler AE 240 balance.

The weight required for the solvents was calculated based on the weight of TPP measured out and the weight ratio required. The liquid solvents were measured by volume using a Pipetman

200 µL micropipette after converting the weight required to volume using the listed density. The solutions were made and stored in 2.0mL clear glass vials with 8-425thd thread open hole screw caps made by Alltech.

Table 3.1: Mixtures of TPP and Solvent TPP:solvent (weight percent) Amount of TPP Amount of Solvent Density of solvent (grams) (g/mL) TPP:Cellulose Acetate, flake 0.0129 0.1036g N/A (10:90) TPP:Cellulose Acetate, flake 0.0212 0.0857g N/A (20:80) TPP:Cellulose Acetate, powder 0.0220 0.1990g N/A (10:90) TPP:Cellulose Acetate, powder 0.0247 0.1733g N/A (20:80) TPP:Cellulose (10:90) 0.0097 0.0903g N/A TPP:Cellulose (20:80) 0.0195 0.771g N/A TPP:D(+)-Glucose (10:90) 0.0115 0.1083g N/A TPP:D(+)-Glucose (20:80) 0.0199 0.0783g N/A TPP:Acetone (10:90) 0.0118 0.1353mL 0.7846 TPP:Acetone (20:80) .0198 0.1009mL 0.7846 TPP:Acetonitrile (10:90) 0.0093 0.1077mL 0.777 TPP:Acetonitrile (20:80) 0.0230 0.1184mL 0.777 TPP:Amyl Acetate (10:90) 0.0101 0.1038mL 0.876 TPP:Amyl Acetate (20:80) 0.0184 0.0840mL 0.876 TPP:Diethyl Phthalate (10:90) 0.0116 0.0932mL 1.12 TPP:Diethyl Phthalate (20:80) 0.0194 0.0692mL 1.12 TPP:Ethyl Acetate (10:90) 0.0119 0.1198mL 0.894 TPP:Ethyl Acetate (20:90) 0.0200 0.0895mL 0.894 TPP:Formaldehyde (not 0.0113 0.0927mL Assumed to be soluble) (10:90) 1g/mL (37%w/w in water) TPP:Formaldehyde (not 0.0203 0.0812mL Assumed to be soluble) (20:80) 1g/mL (37%w/w in water) TPP:Formamide (not soluble) 0.0103 0.818mL 1.132 (10:90) TPP:Formamide (not soluble) 0.0194 0.0686mL 1.132 (20:80) TPP:Acetic Acid(glacial) 0.08570 0.3428g/0.3267mL 1.048 (20:80) TPP:Acetaldehyde (20:80) 0.08777 0.35108g/0.4455mL 0.788 TPP:Acetone (20:80) 0.08119 0.32476g/0.4106mL 0.791 TPP:Ethyl Acetate (20:80) 0.07826 0.31304g/0.3299mL 0.897 TPP:Diethyl Ether (20:80) 0.08158 0.32632g/0.4574mL 0.7134 TPP:2-propanol (20:80) 0.08454 0.3308/0.4209mL 0.786 TPP:Toluene (20:80) 0.08586 0.4344g/0.3961mL 0.8669 TPP:Trichloroethylene (20:80) 0.08016 0.32064/0.2196mL 1.46 TPP:Acetonitrile (20:80) 0.08423 0.43361mL 0.777 TPP:Amyl Acetate (20:80) 0.08403 0.3846mL 0.876 TPP:Diethyl Phthalate (20:80) 0.08042 0.2872mL 1.12

These mixtures were allowed to fully dissolve the TPP (only possible with the liquid samples), and the spectra were collected for each mixture.

Recrystallization of TPP was conducted using various solvents. In these cases a saturated solution of TPP was prepared, and the solvent was allowed to slowly evaporate in the hood by leaving the vial only loosely capped. The amounts of solvent and TPP used for these experiments are listed in Table 3.2.

Table 3.2: Recrystallization of Triphenyl Phosphate in Various Solvents Solvent Solvent amount in µL TPP (amount in grams) Amyl acetate 200µL 0.1265 Acetone 400µL 0.4474 Acetonitrile 400 µL 1.93 m-xylene 400 µL 0.3502 Trichloroethylene 400 µL (d=1.46g/cm3) 0.03366 Diethyl phthalate 200 µL (d=1.112g/cm3) 0.05713 Acetic acid 200 µL (d=1.049 g/cm3) 0.32549

Raman spectra were collected of these recrystallizations periodically during the evaporation process, and are shown in the Results chapter and Appendix.

Experiments were conducted to evaluate the hydrolysis of TPP by water to form diphenyl phosphate. Diphenyl phosphate is acidic, so this hydrolysis was evaluated by measuring the pH of the water solution. Table 3.3 shows the quantity of TPP and water that were mixed. The pH was monitored for the sample at room temperature, every day, the chart of this is shown in the

Results section. The pH was measured using pH paper test strips to evaluate the production of diphenyl phosphate.

Table 3.3: Hydrolysis of TPP TPP (grams) Water (volume) Additives 0.54601g 50 mL None

pH Measurement:

pH was measured of aqueous solutions using Whatman® pH Indicator Paper, Type CF

Cat. No. 2613991 pH 0-14. These strips change color in various pH’s. The resolution of these strips is 1 pH unit.

Raman Spectroscopy:

Instruments:

Two Raman spectrometers were used for this research: an Almega XR Dispersive Raman spectrometer and a NXR FT-Raman module attached to a 6700 FTIR spectrometer. The Almega

XR Dispersive Raman has two excitation lasers at 532nm and 780 nm, with an electronically cooled CCD detector. This instrument has a microscope attachment with 10x, 50x, and 100x objectives. The NXR FT-Raman has a 1064nm YVO4 excitation laser and electronically cooled

InGaAs detector. Both instruments are manufactured by Thermo Fisher Scientific.

Methods:

Spectra were taken of samples using both the FT-Raman and the dispersive Raman. A spectrum of the sample (either liquid or powder) was taken through the wall of a glass vial.

Glass has little Raman activity, though one can see contribution of the glass at low concentrations or at focal points near the glass-sample interface. There was no evidence of interference from the glass in the samples evaluated using this method. Spectra were collected under conditions that maximized signal and signal to noise ratio; for most of the spectra collected the maximum laser power for the instrument was used. The resolution for the dispersive Raman

47 was generally 1.1-1.3 cm-1 and for the FT-Raman the resolution was 1cm-1. Many chemicals and chemical mixtures can be identified by Raman spectroscopy; however Raman spectroscopy has a limit of detection for most chemicals of about one weight percent, though the exact limit of detection is dependent on the chemical.

Appendix 3 gives full spectra with the accompanying meta-data for the collection of each spectrum.

Methods Bibliography

Geddes, A.L., 1954 “The Interaction of Organo-Phosphorus Compounds with Solvents and Cellulose Acetate” The Journal of Physical Chemistry 58(12) 1062-1066.

Tsang, J.-., Madden, O., Coughlin, M., Maiorana, A., Watson, J., Little, N.C. & Speakman, R.J. 2009, "Degradation of 'Lumarith' Cellulose Acetate: Examination and Chemical Analysis of a Salesman's Sample Kit", Studies in Conservation, vol. 54, no. 2, pp. 90-105.

4. RESULTS

Raman spectroscopy was used to evaluate the mechanism of deterioration of triphenyl phosphate containing cellulose acetate composites because of its ability to see changes in bond vibration states. Raman spectroscopy was used to identify the bond responsible for the 726cm-1 peak in TPP and to investigate changes to bond energy occurring in triphenyl phosphate while

TPP was in different chemical mixtures and physical states. Raman spectroscopy was ideal for this investigation because glass and water are largely transparent in Raman spectroscopy and so one can to directly monitor TPP in mixtures without removing aliquots for testing.

Interpreting the spectrum of TPP

The spectrum of TPP undergoes a change when TPP is compounded in cellulose acetate.

This was observed by Tsang et al. in 2009, and the spectra from Lumarith® Coupons in Figure

4.1 show that the 726cm-1 peak in TPP is found at 718cm-1 when TPP is in CA. However TPP is found at 718cm-1 in CA only in locations where the plastic is intact. In areas where the object is deteriorating the TPP peak is found at 726cm-1. Considering Shinagawa’s proposal of the formation of DPP as the cause of deterioration of CA-TPP plastics Figure 4.1 also shows the location of the peaks of DPP.

Figure 4.7 The peaks observed for TPP, both with and without CA. From top to bottom Raman spectra of: Coupon #14, Coupon #26, Coupon 9, TPP, and DPP, taken by Anthony Maoirana.

A series of chemicals related to TPP were analyzed using Raman spectroscopy to determine which bond system produces the 726cm-1 peak observed in the TPP’s Raman spectrum. The chemicals included for this study include tricresyl phosphate, triethyl phosphate, tributyl phosphate, tributyoxylethyl phosphate, triethyl phosphine oxide and triphenyl phosphine oxide. The phosphates all contain the C-O-P bonds and a P=O bond. The phosphine oxides lack the C-O-P bonds but retain the P=O functionality. The chemical structures are shown in Figure

4.2.

The peak at 726cm-1 is due to the C-O-P functional motif, as shown by the data in Table

4.1. Peaks occurring near 726cm-1, within about 20cm-1, are highlighted, and these peaks only occur in chemicals with a C-O-P functionality. The full spectra are shown in Appendix 3.

Table 4.4 Peaks in various chemicals in the range 900-600cm-1. TBP TBOEP TEPO TPPO TPP(s) TCP (l) TEP (l) (l) (l) (s) (s) ------886 m 893 w ------833 s 839 s -- -- 816 -- -- 813 m ------m-s 792 w ------771 773 w ------m-s Occurs only in 727 m-s 734 m-s 731 m-s 722 m 742 m-s -- -- systems with a C- O-P ------685 m 618 m 617 m ------621 s 618 m Names are given in an abbreviated form: TPP-triphenyl phosphate, TCP-tricresyl phosphate, TEP-triethyl phosphate, TBP-tributyl phosphate, TBOEP-tributyoxyethyl phosphate, TEPO- triethylphosphine oxide, and TPPO-triphenylphosphine oxide; with an indication as to their state upon analysis (s)-solid, (l)-liquid. Peaks in wavenumber with an intensity indication: w-weak, m-medium, s-strong, -- no peak

Figure 4.8 Structures of the chemicals analyzed by Raman spectroscopy.

Further evaluation of Raman spectra indicated that of the two bonds involved in the C-O-

P motif, C-O and O-P, the C-O was the most likely candidate for a peak occurring between 750-

700cm-1. This is because no peak is found in the 750-700cm-1 region in phosphoric acid, a molecule that contains three H-O-P bonds. However a peak between 700 and 750cm-1 is seen in molecules like methoxybenzene which contains two C-O bonds in a C-O-C motif.

Logic of Model Systems

Model systems of mixtures of triphenyl phosphate were designed to emulate the peak shift in the TPP seen in TPP-CA systems. The initial goal of this study was to evaluate the potential nucleophilicity of triphenyl phosphate as imaged in Figure 4.16.

Figure 4.9: Proposed first step of a nucleophilic mechanism This mechanism would occur between triphenyl phosphate and cellulose acetate, this image highlights the acetate functional group of cellulose acetate. The variety of cellulose acetate polymer pictured here is cellulose triacetate, though TPP was used with many cellulose acetate with other degrees of acetylation, 2.4 acetyl groups per monomer being the most common.

The hypothesis of TPP acting as a nucleophilic catalyst which deacetylates the CA stems from observations of objects made of CA compounded with TPP. There is a perceived increase

(smell) in the output of acetic acid from cellulose acetate composites containing TPP. This

53 observation tied with the movement of a peak from 718cm-1 to 729 cm-1 in the TPP spectrum in the intact and the destroyed cellulose acetate composite respectively might be explained by the formation of a nucleophile-electrophile complex as pictured in Figure 4.17. The peak shift correlates to an increased C-O bond length which would make sense give an increased P=O bond length as TPP coordinates to CA.

Figure 4.10: Proposed coordination complex of TPP and CA

In order to model this proposed transition state, chemicals were chosen to emulate the electrophilic functionality in cellulose acetate. The choices of analogous chemicals to model cellulose acetate were based on the ester functional group present in cellulose acetate.

Additionally, it was decided that the surrogates would be chemicals that are liquid at room temperature, miscible with triphenyl phosphate at room temperature, and easily evaporated. The functional groups chosen were those that had electrophilic centers similar to that of the ester carbonyl like the ones found in cellulose acetate. A series of surrogates was proposed to evaluate the degree of nucleophilicity of TPP by using electrophiles that had different degrees of electrophilicity. The functionalities included from most to least like the functionality of the

54 cellulose acetate functional groups: esters, ketones, aldehydes, nitriles and alcohols; as well as controls that lacked such electrophilic centers: ethers and aromatic rings.

A series of organic solvents which are liquid at room temperature were chosen because this ensured uniform mixing and an accelerated reaction or interaction time compared with solid- solid solution reactions/interactions. These organic solvents include those listed in Table 4.2.

To ensure better mixing and faster interaction times, chemicals that were solvents for triphenyl phosphate were chosen. Volatile chemicals or solvents were chosen so that they might be driven off and triphenyl phosphate might be better separated from the mixture after observations were conducted.

Raman of Model Systems

Raman spectra were collected of each chemical individually and the mixture of triphenyl phosphate and that chemical. Figure 4.18 shows three spectra, triphenyl phosphate, a mixture of triphenyl phosphate and acetone, and acetone.

TPP 780nm 100% 25um 256scans 3s hires 20110830 TPP:amy l ac etate 10:90 w/w% 780nm 100% 25um hires 256sc ans 2s 20110920 800 0 Amy l Acetate 780nm 100% 25um hires 20110822 256sc ans 2s

700 0

600 0

500 0

400 0 Int

300 0

200 0

100 0

-100 0

800 780 760 740 720 700 680 660 cm-1

Figure 4.11: Spectra of TPP, TPP+Amyl Acetate, Amyl Acetate Acetone Top: Triphenyl phosphate, Middle: Triphenyl phosphate and Amyl Acetae 10:90 w:w, Bottom: Amyl Aceteate. Spectra taken on a Thermo Almega XR Dispersive Raman using a 780nm excitation laser, the macrosample compartment and 180 attachment. The spectral range shown is 650-800cm-1. Samples are housed in glass vials, and spectra were taken through these glass vials.

Peak shifts in the spectra of TPP occurred when TPP was mixed with chemicals like acetone, acetonitrile, amyl acetate and other chemicals containing electrophilic centers. Peak shifts were seen in the spectra of mixtures of TPP in mixtures with chemicals like toluene and diethyl ether and other chemicals lacking electrophilic centers. This does not support the nucleophilic hypothesis, but it supports a new hypothesis. It is possible that the observed peak shift in the Raman spectroscopy corresponds to a change in the free energy states available to triphenyl phosphate in changing from a solid to solid-solid solutions, liquid-liquid solutions or the liquid phase as observed experimentally. The results point to the lengthening of some C-O bonds which produce a Raman peak using a lower energy at 718cm-1. The results also show that in addition to seeing a peak at 718cm-1 there is a peak at 729cm-1, better observed in the model systems due to enhanced spectral resolution over what was possible with solid CA-TPP systems.

The 729cm-1 peak correlates to a shorter C-O bond of higher energy than prior to coordination.

Table 4.2 summarizes spectral peak shifts observed to efficiently convey information from the model experimental systems.

Table 4.5 TPP:Chemical (20:80% w/w) Peaks Observed and Peak Shifts Chemical Functiona Expected Peak(s) Observed Wavenumber l Group Electrophil Shift -icity (-average TPP peak)

Acetaldehyde Aldehyde 1 728.0 718.41 8 1.95 -7.72 Acetic Acid Carboxyli 1 (acidic 728.4 719.60 (glacial) c Acid proton) 1 5 (carbonyl) 2.28 -6.53 Acetone Ketone 2 729.2 727.38 719.01 5 3.12 1.25 -7.12 Acetonitrile Nitrile 2 729.1 727.79 718.99 6 3.03 1.66 -7.14 Amyl Acetate Ester 3 727.7 718.88 3 1.60 -7.14 Diethyl Ether Ether 5 727.6 718.89 2 1.49 -7.24 Diethyl Ester 3 726.5 718.69 Phthalate 2 0.39 -7.44 Ethyl Acetate Ester 3 728.7 727.00 718.41 9 2.66 0.87 -7.72 1-Propanol Alcohol 1 (acidic 728.1 726.14 719.20 proton) 0 1.97 0.01 -6.93 Toluene Aromatic 4 727.0 718.78 Ring 0 0.87 -7.35 Trichloroethy Alkene 4 727.1 718.77 lene 1 0.98 -7.36 TPP solid Summary of Peak Shifts observed using a Thermo Almega XR Dispersive Raman using the macrosample compartment and 180 attachment. Chemical: The solvent TPP was dissolved in; Functional group: The functional group that chemical represents; Expected Electrophilicity: A scale that rates the expected electrophilicity of these functional groups scale 1-5 Best 1, Worst 5; Peaks Observed: the peaks observed in the mixture of TPP:Chemical; Wavenumber Shift: The calculated difference between the observed peak of the mixture and the average TPP peak. The spectra were all taken within 24 hours of each other. The concentration of the samples were 20:80 TPP:chemical by weight. Between each sample a spectrum of TPP was taken to observe any drift from the instrument.

Determination of the Mechanism of Deterioration-Recrystallization

As discussed in the last section, TPP’s peak shifts from 726cm-1 to 718cm-1 whenever

TPP is dissolved in a solvent. A third hypothesis was suggested to fit these facts. This hypothesis states that the peak shift is due to a change in energy of the molecule due to a change in state, from how TPP behaves in single component solid to how it behaves in a solution. The spectra on the right of Figure 4.19 shows that the peak shift returns to from 718cm-1 and 729cm-1 to 726cm-1 as TPP goes from being solvated in acetone to being a crystalline solid.

Figure 4.12 Left: Lumarith® Coupon #14, from Salesman’s kit (spectra taken by Anthony Maiorana) of top to bottom: undegraded, degrading and degraded areas. Right: TPP in acetone (spectra taken by Molly McGath) of top to bottom: fully solvated, partially recrystallized and fully recrystallized TPP.

The spectra on the left of Figure 4.11 were taken of a Lumarith® Coupon from the

National Museum of American History at different locations; MCI project #6147 and NMAH catalogue number is 1983.0538.61. The spectra of Lumarith® Coupons were collected by

Anthony Maiorana as a part of the investigation by Tsang et al. (Tsang 2009). Comparing these two sets of spectra reveal that what is being observed in the CA-TPP system is related to what is seen in the acetone-TPP system. Namely the peak shift is a change in the state of the TPP, when solvated the 718cm-1 and 729cm-1 peaks appears correlating to a lengthening and shortening

58 respectively of the three C-O bonds. As TPP returns to a crystalline state the 726cm-1 peak appears indicating that the three C-O bonds return to a single length and energy.

In support of this observation it was shown by Raman Spectroscopy that when TPP is melted, in its liquid state the 726cm-1 peak shifts to 718cm-1 and 729cm-1. (Figure 4.20) This peak shift at room temperature was observable because TPP can remain a liquid indefinitely, presumably as long as it is isolated from nucleation sites. TPP is not very soluble in water and forms two layers when in liquid form. Heating TPP in water in a glass vial and returning the vial to room temperature allowed for TPP to form droplets in water. These droplets appear to remain in liquid phase indefinitely and only recrystallized when a glass pipet was put into the solution.

Thus it was possible to take a Raman spectrum of the liquid TPP at room temperature.

Figure 4.13 Spectra taken on an Almega XR Dispersive Raman spectrometer at 780nm. The blue spectrum is of the liquid TPP, the red spectrum is of the solid TPP.

The spectra in Figure 4.12 show that there is a difference between the solid and liquid

TPP. This difference occurs whenever TPP is in solution with liquid solvents and this change occurs also when TPP is dissolved in a solid-solution with CA. Figure 4.19 then makes sense as a comparison of TPP coming out of solid-solution on the left and coming out of liquid-solution on the right.

59 pH Measurements: Consideration of a Competing Theory

All pH measurements were done using pH indicating paper. The pH measurements were taken by taking a drop of the TPP-water solution (ensuring only aqueous sampling) and tapping this on to the pH strip. This paper has a resolution of 1pH unit and relies on the color-perception of the individual for estimations more accurate than 1pH unit. Based on color, the estimate of pH was taken at 0.5 pH units, with the understanding of a correlative error margin. pH measurements were employed to investigate the possibility of TPP forming DPP, a mechanism proposed by Shinagawa et al. in 1992.

A mechanism was proposed for the deterioration of cellulose acetate in the presence of

TPP by Shinagawa et al. in 1992. This mechanism hinges on the proposed conversion of triphenyl phosphate to diphenyl phosphate by hydrolysis. In order to test the possibility and validity of this mechanism a number of the experiments conducted by Shingawa et al. were replicated. In one experiment a concentration of 10mM of diphenyl phosphate was dissolved in distilled water, lowering its pH, and Shinagawa et al. proclaim that diphenyl phosphate is a strong acid. This concentration of diphenyl phosphate in water does in fact lower the pH of water to around 2.5.

A second experiment that Shinagawa et al. conducts was the attempt to hydrolyze TPP and produce DPP by exposing TPP to 100% humidity and 90ºC. Shinagawa et al. show that after about 40-50 hours there is a drop in pH of the water to 4 and after 75 hours the pH drops to

2.5. There is no indication in replicating this experiment (Figure 4.21) that there is any generation of DPP as shown, as the measurements taken of the water for this experiment fluctuate from 6.0-8.0.

9 8 7 6

pH 4 3 pH 2 1 0 0 20 40 60 80 Time (hours)

Figure 4.14: Accelerated aging of TPP time vs pH done to replicate Shinagawa’s experiment.

Accelerated aging was done solely in water under reflux, using the same concentration,

1g TPP per 100mL, of water as Shingawa et al. As can be seen in Figure 4.21 while there is minor fluctuation in the pH, from 6-8 over the course of a few days, there is no drastic fall in pH after 40 and 70 hours as reported by Shinagawa et al. which would follow the generation of DPP.

Summary

The peak shift of TPP observed in Raman is due to a solvation effect, and a lengthening of a O-C (O-Phenyl) bond. It was not possible to support or discredit the nucleophilic catalyst mechanism that was initially proposed. The pH experiments do not replicate Shinagawa’s result, indicating that the formation of DPP is unlikely. These results and the conclusions drawn from them will be discussed in the Discussion Chapter.

Results Bibliography

Shinagawa, Y., Murayama, M.; Sakaino, Y. et al., 1992. Investigation of the Archival Stability of Cellulose Triacetate Film: The Effect of Additives to CTA Support N. S. Allen, M. Edge, & C. V. Horie, eds. Polymers in Conservation, 105, pp.138-150.

Stannett, V., 1950. Cellulose Acetate Plastics, London: Temple Press Limited.

Sully, D.B., 1962. Chapter 10: Plasticisers. In H. W. Chatfield, ed. The Science of Surface Coatings. pp. 277-301.

Zugenmaier, P., 2004. 4. Characteristics of cellulose acetates— 4.1 Characterization and physical properties of cellulose acetates. Macromolecular Symposia, 208(1), pp.81-166.

5. DISCUSSION

This chapter discusses the results of the experiments used to discern the mechanism of the deterioration of cellulose acetate (CA) in the presence of triphenyl phosphate (TPP). This chapter will look at how CA-TPP composites deteriorate, and how this deterioration is characterized. What was learned is compared to previous theories of the deterioration mechanism of CA-TPP composites.

Characterizing the Spectrum of Triphenyl Phosphate

The phenomenon surrounding the Raman spectroscopic shift observed in the TPP spectrum from 726cm-1 to 718cm-1 and 729cm-1 is related to an energy change in a molecular bond. In order to discern which bond Raman spectra were collected of chemicals analogous to

TPP. The chemicals studied all have functionalities similar to those found in TPP. By isolating out the various functionalities of TPP using analogs without these functionalities: aromatic carbon rings, P-O-C and P=O ester bonds, it was possible to look for changes in the resultant spectra. (Geddes 1968)

The peak that occurs at 726cm-1 in triphenyl phosphate is tied to the C-O-P motif. To compare TPP’s aromatic structure of a triphenyl phosphate ester, a spectrum of triethyl phosphate was collected. There was an observed change in the location of the 700-750cm-1 peak but there was still a peak in this region. In looking at trialkyl phosphites, lacking the P=O, again there was a change in location of a peak in the 700-750cm-1 range but there was a peak in this range. Only with the phosphine oxides, lacking the P-O-C, were there no peaks in the 700-

750cm-1 region as summarized in Table 4.1 in Chapter 4: Results. Phosphine oxides lack the P-

O-C motif/functionality, so it is this feature that absorbs energy between 700-750cm-1 and it is

63 this feature that is undergoing the most change as TPP goes from solid to solid-solution, liquid- solution or liquid.

The fact that the molecule absorbs 8cm-1 of energy less in solution than it does as a solid correlates to a long bond of lower energy. There is also a second and usually smaller peak at

728-729 cm-1 (taking 2-3cm-1 more energy) and this correlates to a shorter bond length of higher energy. Most likely the change is being observed in the O-C portion of the P-O-C bond system.

Peaks between 700 and 750 are observed for 1,3-dimethoxybenzene and 1,4-dimethoxybenzene, while no peaks are seen in this range for potassium phosphate dibasic. The observed 8 cm-1 of energy difference for a bond (about 0.096 kJ/mol), or perhaps two of the O-C bond systems would correlate to a lengthening of the O-C bonds. The 728-729cm-1 peak would correlate to a slight shortening of the third O-C bond system. The effect of increasing the bond length of the

O-C bond is likely due to the increased motion of the molecule in solution and liquid phases.

(Discussed further in the section below) In solid-solution these bonds would be frozen at specific lengths. The return of the peak to 726cm-1 seen in the TP spectrum relates to the shortening of one or two of these bonds and lengthening of the third, as TPP comes out of solution and crystallizes.

Investigation of the Process of Deterioration of CA-TPP Composites

Model systems were used to understand the solvatochromatic shift observed for TPP.

This shift goes from 726cm-1 for solid TPP to718cm-1 and 728cm-1 for solvated TPP. A solvatochromatic shift is a shift observed in the spectrum of a chemical when the chemical is dissolved. It was initially thought that the chromatic shift due to bond lengthening was due to a complex formation between TPP and CA. The experiment to test for this complex formation

64 used the electrophilicities of the different solvents to show the strength of the nucleophilicity of

TPP.

Model systems were designed to test a relationship between the electrophilicity of the solvent in relationship to the observed shift in TPP’s Raman spectrum. If TPP interacted (the

726cm-1 peak would be observed to shift) with a weaker electrophile like an ester (as compared to a ketone) it was a stronger nucleophile. Liquid solvents provided faster interaction times than solid solvent based systems. Liquid solvent based model systems allowed the liquid solvent to be driven off over time and collect spectra as TPP condensed and crystallized.

As shown in the results, no nucleophilic trend was observed correlating with the 728 to

718cm-1 peak shift. Instead what these model systems provided was proof of a solvatochromatic shift. The peak shift observed in triphenyl phosphate’s spectrum is tied to a change in its crystalline state. This was indicated by the Raman spectra taken of triphenyl phosphate dissolved in a variety of solvents.

It was found that the 726cm-1 peak of TPP shifted whenever TPP was solvated or is melted and is in its own liquid phase as shown in Figure 4.12 of Chapter 4: Results. In solid- solid solutions, liquid-liquid solutions, or the liquid phase the triphenyl phosphate peak is observed to shift from 726cm-1 to 718cm-1. This is directly correlated to the observed peak shift within a solid-solution phase of intact areas of a cellulose acetate-triphenyl phosphate composite

Lumarith® coupon as seen in Figure 4.11 of Chapter 4: Results.

The possibility of there being a reaction between TPP and cellulose acetate is a research area that is still open for testing, though to date no data has been generated that proves TPP acts as a nucleophile. The observation of the return of this peak to 726cm-1 in deteriorating cellulose

65 acetate composites is tied to the recrystallization of triphenyl phosphate from the solid-solid solution it was in with cellulose acetate.

Triphenyl Phosphate Recrystallization

Triphenyl phosphate was recrystallized from different solvents to monitor the reproducibility of the chromatic peak shift to 726cm-1 as the recrystallization occurred. The liquid-solution of TPP in a solvent like acetone, amyl acetate or toluene was found to emulate

TPP’s solid-solution with cellulose acetate. However, the liquid-solution separation and recrystallization of TPP takes place on a shorter time scale than the solid-solution separation and recrystallization seen in cellulose acetate (with an apparent time scale of decades).

Triphenyl phosphate is soluble in a variety of solvents due to its different functional groups. It is soluble in polar solvents like acetone and 2-propanol because of the phosphate ester functionality and is soluble in the non-polar solvent toluene because of its aromatic groups. TPP is only sparingly soluble in hexanes and at a concentration lower than observable by Raman spectroscopy. It is not miscible in water, though when surrounded by pure water it can remain in the liquid phase indefinitely, presumably as long as it is kept from nucleation sites. Thus TPP was dissolved in a variety of solvents and the spectrum of the mixture was monitored over time as the solvents volatilized off.

Triphenyl phosphate’s recrystallization from a variety of solvents matches with what is observed as a Lumarith® CA-TPP coupon degrades. In the undegraded portions of the

Lumarith® coupon the spectra of TPP in cellulose acetate matches with that of TPP dissolved in a solvent. As is seen in Figure 4.11, the spectrum collected in a degrading area of a Lumarith® coupon matches with that of an area where TPP is observed as beginning to crystallize out of

66 solvent, but where solvent is still observed. Finally where the Lumarith® coupon has significantly degraded this spectrum matches with that of the recrystallized triphenyl phosphate.

What is shown in the results section is a comparison between the spectra taken of the

Lumarith® coupon and the spectra taken of TPP recrystallizing from acetone. Despite the differences brought about by pressures of a solid-solution compared with a liquid solution these spectra show parallels between the recrystallization of TPP from liquid solution and the destruction of the coupon as TPP recrystallizes. Notice the spectrum of the most degraded areas of the coupon correlate to the spectrum of the mostly recrystallized TPP. The partially recrystallized TPP spectrum correlates to the spectrum of the partially degraded area of the coupon and the spectrum of the intact area of the coupon correlates to the completely solubilized

TPP. While the recrystallization from a volatile solvent is different from the recrystallization from a solid-solution because of the added physical pressure of recrystallizing in a solid it is possible to see a correlation between the behavior of TPP recrystallizing from a liquid solvent and the deterioration of Lumarith® coupon. These results show that the recrystallization of TPP within the cellulose acetate matrix is the cause of the deterioration of the object.

Evaluating the Possibility of Diphenyl Phosphate Generation from Triphenyl Phosphate

The hydrolysis of triphenyl phosphate (TPP) to form diphenyl phosphate (DPP) is a proposed mechanism of deterioration for cellulose acetate polymers plasticized with TPP.

(Shinagawa 1992) However diphenyl phosphate (DPP) has not been observed in either the

Lumarith® coupons (Tsang 2009). The first step for analyzing the possibility of this kind of interaction was to replicate Shinagawa’s experiment. To better evaluate the possibility that TPP hydrolyzes to form DPP, TPP was exposed to water at reflux temperature for this experiment,

(90ºC in Shinagawa’s) and the pH was monitored over time.

While fluctuation occurred in pH measurement, this fluctuation was never more than one pH unit away from a pH of seven, or neutral. This experiment did not show a large decrease in pH that would be an indication of the generation of DPP within the water. The results of the hydrolysis experiment question the mechanism proposed by Shinagawa et al.

Discussion Bibliography

Geddes, A.L., 1954 “The Interaction of Organo-Phosphorus Compounds with Solvents and Cellulose Acetate” The Journal of Physical Chemistry 58(12) 1062-1066.

Gross, R. a & Kalra, B., 2002. Biodegradable polymers for the environment. Science (New York, N.Y.), 297(5582), pp.803-7. Available at: http://www.ncbi.nlm.nih.gov/pubmed/12161646 [Accessed March 5, 2012].

Hagedorn, M., Ossenbrunner, A. & Wilmanns, G., 1937. Film, 2071462th edn, United States of America.

Rånby, B.G. & Noe, R.W., 1961. Crystallization of Cellulose and Cellulose Derivatives from Dilute Solution. I. Growth of Single Crystals. Journal of Polymer Science, 51(155), pp.337-347. Shinagawa, Y., Murayama, M. & Sakaino, Y. 1992, "Investigation of the Archival Stability of Cellulose Triacteate Film: The Effect of Additives to CTA Support", The Proceedings of an International Conference Organized by Manchester Polytechnic and Manchester Museum, vol. 105.

Stannett, V. 1950, Cellulose Acetate Plastics, Temple Press Limited, London.

Sully, D.B., 1962. “Chapter 10: Plasticisers.” In H. W. Chatfield, ed. The Science of Surface Coatings. pp. 277-301.

Svetich, G.W. & Caughlan, C.N., 1965. Refinement of the crystal structure of triphenyl phosphate. Acta Crystallographica, 19(4), pp.645-650.

6. CONCLUSIONS

Triphenyl phosphate (TPP) induced deterioration is a catastrophic occurrence in cellulose acetate (CA) plastics. Because of the prevalence of the use of cellulose acetate in mid-20th century objects and the use of TPP as a plasticizer, this deterioration is a growing problem in museum collections containing objects from this time period. It is necessary to understand this deterioration and why it occurs before addressing this problem either through preventive or interventive conservation.

TPP’s peak shift of 726cm-1 to 718cm-1 and 729cm-1 as seen by Raman spectroscopy is tied to the state of the molecule. This shift is seen when TPP is mixed with different organic solvents which indicates that this peak shift is a solvatochromatic shift that is due to the solvation of TPP in different matrices; either as a solute in a solid-solution or liquid-solution. The 726cm-1 peak was identified as relating to the C-O of the C-O-P bond motif by taking Raman spectra of a series of compounds related to TPP. The movement of the peak in Raman spectroscopy from

726cm-1 to 718cm-1 indicates a lowering of the bond energy associated with the peak, and that this bond is now longer. The movement of the 726cm-1 peak to 729cm-1 correlates with a slight increase in the energy of the bond and the bond is now shorter. This effect correlates well with the solvation or change in state of the molecule from a solid phase to a liquid or a solute in a solution. The return of the 718cm-1 peak to 726cm-1 indicates a separation of TPP from that solution and as the 718cm-1 is still seen when TPP is in liquid form a solidification or crystallization of TPP. The TPP peak occurs at 718cm-1 in intact plastic and in areas of degraded plastic TPP appears at 726cm-1. The experiments do not indicate that TPP forms a nucleophilic complex with cellulose acetate from which TPP catalyzes the cleavage of acetyl groups. There

69 also is no indication that there is the formation of DPP from TPP in experiments done to emulate the results of Shinagawa et al, (1992).

The understanding of the long-term mechanism of degradation of CA containing TPP can inform future design of materials and objects as well as the conservation of aged objects. The future designer of a material may wish to remove this kind of deterioration or they may employ it as an intentional deterioration mechanism. This knowledge provides a better overall understanding and informed choice for conservators and future designers.

Conclusion Bibliography:

Shinagawa, Y., Murayama, M. & Sakaino, Y. 1992, "Investigation of the Archival Stability of Cellulose Triacteate Film: The Effect of Additives to CTA Support", The Proceedings of an International Conference Organized by Manchester Polytechnic and Manchester Museum, vol. 105.

7. CASE STUDY: AIRCRAFT RECOGNITION MODELS

Many mid-20th century objects were made of cellulose acetate (CA) plastics. 168 CA plastic aircraft recognition models (ARMs) (Figure 7.1) from World War II (WWII) at the

National Air and Space Museum (NASM) provided a case study for the deterioration associated with CA plastics compounded with triphenyl phosphate (TPP). These models entered into the

Smithsonian’s collections primarily in three large groups directly from the company that made them. Today the models are shrinking, distorting, cracking Figure 7.2 and falling apart into pieces often millimeters in dimensions as seen in Figure 7.3.

Figure 7.15: Aircraft Recognition Models (ARMs) on Display at the National Air and Space Museum (NASM), Washington D.C. Close up pictures of two models on the wall, and one that fragmented upon removal.

Figure 7.16: Models shrink, warp, crack and pieces fall from them to the floor.

Figure 7.17: Fragments of models litter the cases at NASM prior to removal of the exhibit. (Photograph used courtesy of Odile Madden).

The ARMs were on exhibit from when the Smithsonian’s NASM opened in 1976 until the exhibit was deinstalled on August 2, 2011 (www.collectair.com). This collection has received attention from its inception by people who were avid collectors and those who were interested in the history of aircraft recognition. One such person is Steve Remington who owns and operates a The Friend or Foe? museum in Santa Barbara. He documents the condition of installation at NASM on his museum’s webpage:

“The World War 2 gallery … …was one of the initial galleries to be installed for the

1976 opening of the museum. I have numerous photos of this gallery dating back to 1978

and… … not much of anything has been changed, or taken care of since then. At the

opening, a large display of recognition models was elegantly displayed behind glass on

the mezzanine wall, each model mounted on a peg extending vertically from the wall and

arranged by country. Over the years, this display, which is open top and bottom for

ventilation, appears to have never been cared for - dust and deterioration has taken its

toll to the point where I would be embarrassed to have anything to do with such a

miserable exhibit. I have photos showing the gradual deterioration of many of these

models since 1978 - some have crumbled to the point that there is nothing remaining save

an unidentifiable chunk of useless cellulose acetate left on the peg.

(Steve Remington on www.collectair.com)

Steve Remington investigated the deterioration of the ARMs in dealing with his own collection. Rapid deterioration into unrecognizable fragments occurs with many ARMs so the problem is not isolated to the ones held within the Smithsonian and appears to be a problem inherent to the planes. But no planes were as in the public view as those housed within the

NASM’s collection. Steve Remington noted this in his museum’s webpage.

“The Smithsonian’s National Air & Space Museum is perhaps the prime

repository and exhibit of the ‘melting’ recognition models, although I’m certain

the exhibit curators wouldn’t want that honor bestowed on the museum.”

Steve Remington on www.collectair.com

Chris Moore, the curator who inherited the aircraft recognition models and their inherent vices, did not want that honor. He worked with Odile Madden at the Museum Conservation

Institute (MCI); they conducted a condition survey of the collection with a team of people, and the planes were transferred to MCI on August 2, 2011. (Madden 2011) The analysis and investigation into the deterioration of these planes and into their technological past is being conducted at MCI.

Background

On December 7, 1941 Pearl Harbor was attacked by the Japanese. This attack launched the United States into World War II, as the next day President Roosevelt declared war on the

Axis nations. What hit home for many people was the speed of the attack and a newer, more pervasive threat from the air in the form of airplanes. Aircraft had been of increasing use through the end of the First World War, and by the end of the Second World War a single plane was loaded with a bomb that destroyed a city.

The US Navy recognized the new threat from the air and trained members of the military and civilians to recognize enemy and allied aircraft.

A number of methods were developed to assist both military and civilian air spotters in the identification of aircraft. These methods included the use of spotter cards and kites (Figure

7.4).

Figure 7.18 Paul E. Garber with target kite. (Source: Smithsonian National Air and Space Museum)

However these techniques were only able to teach people to evaluate a plane from a limited number of perspectives. The cards showed a side silhouette, the front and underside of a plane and the kites showed the underside of a plane.

Lieutenant Commander Paul E. Garber was involved with aircraft from a young age. He started the aircraft collection at the Smithsonian. He was contracted by the Navy to develop mentions methods for spotters to identify planes on December 8, 1941 as he mentions in his report to the Navy summarizing his work in the Special Devices Division (Garber 1945). Garber designed kites as identification methods and for target practice, see Figure 7.4, and he developed a plan to make model airplanes at multiple scales that could be used to identify both enemy and allied aircraft from any perspective.

Models needed to be produced in large numbers and rapidly. Materials were used with varying degrees of success. Metal is heavy and was needed for the war effort. Mannequin plaster was brittle and could break in transit. Papier-mâché did not hold fine detail well. It was time-consuming and there were issues with reproducibility in using wood. Rubber held the detail well but the model wings drooped. Cellulose acetate plastics have the advantage of being thermoplastic materials that can be injection molded when compounded with the right plasticizer. Cellulose acetate plastic is lightweight, could be formulated to retain its shape well and could be mass produced quickly, thus CA plastic proved to be the best fit and was used as the material for ARMs. (Mikesh 1973)

A major question that presents itself is when examining these objects now is what are the components of this CA plastic. After what is in the material is known one may start to answer the questions surrounding the mechanism of degradation and how it can be arrested or prevented, and when possible, reversed.

Because Garber played an integral role in the development of these models, a set came to the Smithsonian. They were delivered directly from the manufacturer largely in three shipments in 1943, 1948 and 1953. Though the models produced for aircraft spotters were made by more

76 than one company, of the ones in NASM’s collection all but 9 Design Center models were made by Cruver Manufacturing Company. The models that came to the Smithsonian were never used for identification and from the time of arrival the models were under the care of the museum.

It has been seen nationwide in collections of these planes that there some of the models degrade. (www.collectair.com) The models at the National Air and Space Museum of the

Smithsonian Institution are no exception. According to a survey conducted by Chris Moore and the conservation staff of the NASM approximately 10 percent of the 168models had significantly degraded, and some were no longer recognizable.

The recognition models are currently at the Museum Conservation Institute. Some models have significantly warped, cracked and disintegrated into unrecognizable pieces and cannot be reassembled; often these pieces are only a few millimeters in all dimensions. This collection provides an excellent naturally aged experiment. A question that arose was whether or not the degrading models contain triphenyl phosphate (TPP). These objects can give information on degradation mechanisms and inform future conservators’ choices of how they might house and treat CA plastics that degrade in this manner, especially the special class of CA-TPP plastics that these were suspected to be.

This case study calls for a reverse-engineering of objects from a pivotal time-period in the history of technological advance. Plastic, as a material, has significantly altered the way people live, and it has been interesting and at times frustrating to see how difficult it is to understand an object that was made in the last 100 years.

The formulation and production of these objects are factors of interest in understanding how and why these planes break-down. A key piece of information would be a general formulation for the planes, which would in turn allow for the measurement of any changes that

77 have been observed in relative amounts of chemicals that appear in the fragments of these planes.

However an exact formulation for the planes or for their molding powder has not yet been found.

In tracing the history of the planes, some facts and figures of the production have been forth-coming. Cruver Manufacturing Company went out of business since the creation of these planes, and it is currently uncertain whether any records survive, or were ever made.

The identification and characterization of these models required Raman spectroscopy, X- ray fluorescence spectroscopy, and scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX).

This case study is a product of collaboration between the Museum Conservation Institute and the Smithsonian’s National Air and Space Museum. The objects analyzed belong to the collection of the National Air and Space Museum.

Methods

Objects – Aircraft Recognition Models

168 aircraft recognition models from World War II were on exhibit at the National Air and Space Museum from 1976-2011. These models came to the Smithsonian’s collection in batches, as shown in Table 7.1.

Table 7.6: Year and Quantity of Collection of Aircraft Recognition Models Year Donor Manufacturer if Number of Models known 1943 Cruver Cruver Manufacturing 82 Manufacturing Co. Co. 1944 Design Center Design Center 9 1948 Cruver Cruver Manufacturing 82 Manufacturing Co. Co. 1949 Wright-Patterson 5 Airforce Base 1953 Cruver Cruver Manufacturing 48 Manufacturing Co. Co. 1976 Kincaid (Private 2 Collection)

Almost all aircraft recognition models came directly from the factory that manufactured them, and most were manufactured by Cruver Manufacturing Company in Chicago, Illinois.

More information about the provenance of these models is given in the appendices. The collection was put on exhibit for the opening of the National Air and Space Museum in 1976.

The collection remained on exhibit until the panels holding the aircraft recognition models were taken down and shipped to the Museum Conservation Institute on August 2, 2011. 15 models are not on the panels and these objects were those analyzed using non-destructive techniques. The rest remain on the panels in storage in a secure location and due to their fragility much care and assessment must be done prior to analyzing these models.

The majority of the aircraft recognition models remain on the panel they were mounted on for exhibit. Table 7.2 lists those that have been removed from the panels. XRF spectra taken of these models are available in Appendix 2.

Table 7.7: List of Planes analyzed by XRF Accession Number Plane Description Testing 1944-30 XRF 1944-31 XRF A19440026000 1948-85 SB2C-2 Helldiver XRF 1953-32 XRF USArmy 42 DeaccObject-172 XRF A19430065000 Germany-30 Heinkel HE 113 XRF A19430116000 Great Britian-21 Vickers XRF Wellington A19480040000 Great Britian-24 Fairey Barracuda XRF Japan-30 Lily XRF Russia-3 XRF A19530024000 US-49 Model, Aircraft, XRF Recognition, Waco CG-4A A19480025000 USArmy-31 Model, Aircraft, XRF Recognition, Douglas C-54 Skymaster D19430084000? USArmy-48 Model, Aircraft, XRF Recognition, Republic P-47B Thunderbolt A19430127000 USNavy-12 Model, Aircraft, XRF Recognition, Sikorsky JR2S-1 Excaliber A19440026000 USNavy-14 Model, Aircraft, XRF Recognition, Curtiss SB2C-2 Helldiver (Floats)

Samples – Aircraft Recognition model fragments

Fragments of aircraft recognition models were collected from the bottom of the display case while the models were on display and presented to the Smithsonian’s Museum Conservation

Institute without any more attribution.

Extraction experiments were conducted on unattributed fragments of aircraft recognition models. Unattributed fragments of aircraft recognition models were chosen at random from a collection of these fragments. A single fragment, (no greater than 5mm on a side) was placed in a solvent in a 2mL glass vial. These fragments were allowed to sit for at least 4 weeks before the solvent was removed, and an aliquot of these solvents was placed on a glass microscope slide to dry overnight. The residue was analyzed using the microscope attachment of the Almega XR

Dispersive Raman spectrometer.

X-Ray Fluorescence Spectroscopy:

Instrument:

A Bruker Artax X-ray Fluorescence Spectrometer, with Helium gas atmosphere, was used for elemental analysis of aircraft recognition models and model fragments.

Method:

Samples and objects were placed on a table underneath the sensor for the Artax. The focus of the X-ray beam was adjusted to focus on the surface of the object using the protocols of the instrument. A rhodium source generated an X-ray of 50keV. A spectrum was collected for each object which measured the x-ray fluorescence of elements of atomic mass greater than sodium on the periodic table. No filter was used for these measurements, which means that the chlorine signal (when present) is hidden under the Lα lines of rhodium. All spectra were collected using instrument parameters of 600µA current, with 60 seconds live time and most had

81 between 4.3-13.5% dead time with one outlier at 38% dead time. Each aircraft recognition model was tested in three locations, generally represented by (when all were present): the fuselage or body of the plane, one of the two wings (proper left when present), and along a break-edge. Additionally larger unattributed fragments of aircraft recognition models were analyzed using this technique.

SEM-EDX:

Instrument:

A Hitachi S-3700 Scanning Electron Microscope, with an IXRF Systems (Electron

Dispersive X-ray) was used to image unattributed fragments from aircraft recognition models; to map elemental distribution and image microstructure of these fragments.

Method:

Unattributed fragments of aircraft recognition models were chosen at random from a collection. Using metal tweezers, these fragments were placed on carbon sticky paper on an aluminum stub. These samples were placed, uncoated, under high pressure vacuum (Nature mode) in the Scanning Electron Microscope. Images were taken of the samples at varying working distances, magnifications and keV, and these conditions are described in the caption for the image in the body of the dissertation or in the meta-data for each image found in the

Appendices.

Raman Spectroscopy

Method:

This method was used when evaluating the residues that were extracted from unattributed fragments of aircraft recognition models. The microscope optics were used to focus the laser beam at a residue on a microscope slide by using higher magnification (typically 50x or 100x

82 objectives), as this lowers the focal depth and reduces contribution from the glass slide behind the residual sample and increases the contribution from the residual sample.

Results

X-ray Fluorescence Spectroscopy

X-ray Fluorescence Spectroscopy (XRF) was used to provide elemental analyses of the aircraft recognition models. Specifically, XRF was employed to address the question of the presence of triphenyl phosphate (TPP) in the aircraft recognition models. Because the aircraft recognition models (ARMs) have chemical components that fluoresce in Raman spectroscopy and this fluorescence drowns out Raman signal from other chemicals, it is not possible to see

TPP in situ. XRF was used to determine whether TPP might be in these objects by looking for the element phosphorus 15P. If no phosphorus is present, TPP cannot be present; of course, if phosphorus is present there is no guarantee that TPP is present. XRF was used to determine whether or not there was a possibility that TPP was present, rather than to affirm that TPP is in any of the ARM.

Figure 7.19: XRF Spectrum of aircraft recognition model with the original Cruver catalogue number 1944-30. This spectrum shows the presence of phosphorus. This spectrum was taken of this model at the nose of the fuselage of the plane using a Bruker Artax X-ray Fluorescence Spectrometer. (Spectrum taken with Dawn Planas)

Phosphorus is seen in the models that have been analyzed using XRF. Of the 168 aircraft recognition models, 15 have been examined by XRF. A typical spectrum of these models in

Figure 7.5 shows that these objects contain many different elements.

There are variations between models as well as within a single model as to which elements are found. A single model might have been molded in a single piece but most models were constructed from a few separate pieces. Most typically, it appears that they were constructed in three pieces: the fuselage or body, the wings and the tail. So it is not surprising to find compositional variation within a single model as seen in Figure 7.6.

Figure 7.20 Left: USArmy-48 engine break Right: USArmy-48 tail fuselage

As is shown in Figure 7.6, within a single model there can be a large difference in composition, in this case between the engine and the tail of the model, which were identified as different pieces that were assembled together. More XRF spectra of these models are summarized the Appendix 2.

The models that have been analyzed are those that have been removed from the panels that held the planes when they were on exhibit. Currently the majority of the planes are still on these panels and, due to their fragile nature, XRF analysis has been put on hold. The ARTAX

XRF instrument does not need to touch the planes to gather an elemental spectrum and is ideal for the analysis, except that the planes need to be moved to it. Additionally there are considerations of positioning the instrument to take spectra of the remaining planes as the planes are mounted on a board and there are concerns about positioning the instrument over them.

Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX) was used to image unattributed fragments of aircraft recognition models and to map elemental information from the surfaces of these fragments on a microscopic scale. These fragments were

85 taken from a collection of unattributed fragments from the bottom of the exhibit case that housed the aircraft recognition models collected by the curator of this collection: Chris Moore,

Aeronautics Museum Specialist. The fragments are considered to be “self-sampling” as they have fallen from the object without any human intervention or sampling. The size of these fragments ranges from a few millimeters in all dimensions, to a few centimeters.

Scanning Electron Microscopy allows for greater resolution imaging on a smaller scale than light microscopy. Light microscopy is limited to the resolution of the light encountering the sample, that is features smaller than the wavelength of light encountering the sample are not visible. Practically speaking looking at violet light alone (the shortest wavelength visible) this means the resolution is around 400nm or .4um. In contrast SEM can resolve features at about

250x the magnification of a light microscope and can image objects on a 5-10nm scale. SEM was used in order to investigate the fine microstructure of these fragments. Energy-Dispersive

X-ray Spectroscopic analysis and mapping done during the collection of SEM images allowed for elemental information to be gathered from these samples. The mapping function of this technique is especially powerful. In addition to providing information as to which elements are present, mapping determines where these elements are found in the object. The location and morphology of materials containing different elemental signatures are discernible within the fragments. However the elemental mapping is limited to locating elements present in the sample and does not answer the question of what chemical compounds are present, though this gives hints as to what chemicals might be there.

Goal of the SEM-EDX investigation were to characterize the surfaces and microstructure of the aircraft recognition model fragments and to use elemental mapping to determine the heterogeneity of the material. In characterizing the surfaces and microstructure of the fragments,

86 it was possible to record micro-scale concoidal, or shell-like texture, fracture patterns on their surfaces and to trace the micro-fissures within these fragments. The heterogeneity of the material was shown by mapping the location of elements and by mapping the occurrence of different phases, and potential crystal formation.

Characterizing the Surface and Microstructure of Fragments from Aircraft Recognition Models

In characterizing the surface and microstructure of the fragments from the Aircraft

Recognition Models a first step was to characterize the fragments visually. Concoidal fracturing of fragments can be seen with the naked eye as shown in Figure 7.7. The resolultion available with the naked eye is ~10microns, and the concoidal “waves” are about 3mm apart.

A B

Figure 7.21: Concoidal fracture patterns are visually apparent in this fragment with dimensions of 2.3cm x 1cm

Under the SEM, at low magnification, more detail of the concoidal fracture patterns on the surfaces of these fragments is visible as is seen in the image in Figure 7.8. This kind of breakage indicates the largely amorphous nature of the solid material and is typical of failure of amorphous solids under stress.

Figure 7.22 Concoidal fracture pattern from a fragment of an Aircraft Recognition Model, number 1944-31. This secondary electron image was taken at a magnification of 650x, at a voltage of 15.0kV, with a working distance of 11.1 mm.

However there are many areas of breakage that do not conform to this type of fracture.

SEM is used to examine these areas of breakage in greater detail. It was found that breakage occurs in areas containing crystalline materials that are rich in phosphorus as indicated by element distribution maps generated using EDX. These crystalline materials are often found in crevices and breakage areas as seen as long purple lines in the image in Figure 7.9.

A B

Figure 7.23: SEM-EDX images of aircraft recognition model fragments. Magnification 40x, Working Distance 12.0mm, kV: 10.0. A: Secondary Electron image of a fragment of an aircraft recognition model. B: Elemental Map of fragment with oxygen, carbon phosphorus and aluminum (from the stud)

The images clearly show that along micro-fissures there is an increased presence of phosphorus rich material. Carbon is shown in green and phosphorus is shown in purple. Oxygen is present both in the carbon rich material, which makes sense given the composition of cellulose acetate, and in the phosphorus rich material, which is consistent with triphenyl phosphate. A correlation is visible at higher magnification between the location of cracks and the presence of either crystals or veins of phosphorus rich materials. (Figure 7.10)

A B

C D

Figure 7.10 A,B,C,D: Working Distance 10.3mm with voltage of 90.0kV; A,C SEM images (secondary electron), B,D SEM-EDX map images., A,B: 270x Magnification, C,D: 650x Magnification.

These fragments show that the aircraft recognition models have microfissures, some of about 1-2µm in width and varying in length and shape as seen in Figure 7.10 and C. These microfissures often contain phosphorus rich materials, as seen in the elemental map overlay.

Additionally there are veins of phosphorus rich compounds running through these fragments as shown in the elemental map images Figure 7.10 B and D. The veins of phosphorus rich materials are present in fissured areas and on the surface of the fragment. It should be noted that due to the low density of the material, the electron beam penetrates deeply into the sample and veins are visible above and below the surface, both with and without elemental mapping.

The heterogeneity of the material was shown by employing elemental mapping

Polymers have differing levels of crystallinity that affect their working properties. While some polymers may be totally amorphous, in others portions of chains may be in a crystalline

90 state and portions may be in an amorphous form. The fraction of crystallinity in polymers ranges as percentages of the total polymer, and the degree of crystallinity is dependent on the type of polymer. Cellulosic polymers have varying degrees of crystallinity and cellulose acetates can have multiple crystalline forms (Zugenmaier 2004). The degree of acetylation of the original cellulose acetate impacts the crystallization of the polymer, the acetylation of the cellulose acetate in the ARMs is not currently known. Additionally, crystallinity is impacted by the presence of additives and the processing and manufacturing methods of the final product. It was posited prior to SEM-EDX imaging that a solid-solution phase of cellulose acetate and triphenyl phosphate would be observed as areas with mixtures of high carbon and phosphorus content.

Based on prior knowledge from Tsang et al 2009, there was an added expectation that in areas of deterioration that there would be a separate phase of triphenyl phosphate observed as an area of high phosphorus content. Thus it was anticipated that there would be variation in the location and qualitative concentrations of elements seen in individual elemental maps as seen in Figure

7.11.

A B C D

E F G

Figure 7.24: A: multi-element overlay map B: carbon elemental map C: phosphorus elemental map D: oxygen elemental map E: magnesium elemental map F: chlorine elemental map G: calcium elemental map

There are areas in these maps that the detector does not receive signal from and these are

“true shadows” due to features blocking electrons from getting to the detector. These true shadows are most visible in Figure 7.11B which shows the carbon elemental map. Looking at other elemental maps there are areas that only appear darker on some of the elemental maps but not all. These darker areas indicate relative absence of an element and areas that are brighter indicate a relative abundance of an element. For example, there are only a few areas with a relatively large concentration of calcium as shown in Figure 7.11G. In Figure 7.11C there is an area containing large amounts of phosphorus given the brightness in the center of the image and there are veins of phosphorus material. It is not possible to quantify the absolute concentrations or amounts of the elements mapped, rather these maps give indications of relative quantities.

In an effort to better focus on these relative quantities in Figure 7.12 are shown two elemental maps, carbon in green on the left, and phosphorus in purple on the right. Circled in red are areas where there is a notable absence of phosphorus which appear black on the phosphorus map Figure 7.12B. Initially it might appear that these are areas of shadow, where the detector was getting no signal. However upon comparing the elemental map of carbon,

Figure 7.12A, it is possible to see that these areas are rich in carbon. This indicates that these areas are ones that carbon rich and phosphorus poor, perhaps another phase or even crystalline carbonaceous material (given the cubic and hexagonal shapes seen and these are typical shapes

92 for both cellulose and cellulose acetate upon recrystallization). (Rånby 1961)

A B

Figure 7.25: Images taken at magnification of 800x, 15.0KV and working distance of 12.7mm A: carbon map of an area of a fragment taken from an ARM, B: phosphorus map of an area of fragment, the red circles highlight areas of high carbon content and phosphorus absence.

These rich areas of carbon without phosphorus indicate that phosphorus containing chemical has migrated and the remaining material (polymer) has separated and perhaps crystallized. Alternatively, it is possible that this is a fragment of crystalline cellulose acetate that has been present since the synthesis of the material. However the prevalence of this phenomenon in the samples examined would indicate that they are likely not random later deposits.

Whether these carbon rich crystalline fragments are from the original molding powder used to make the objects and never formed part of a solid-solution, or evolved over time is a difficult question to answer. However, these fragments of apparently low phosphorus content are in close associate with areas of veins of phosphorus rich materials which based on extraction experiments are TPP. Figure 7.12, a higher magnification of the images shown in Figure 7.10

93 and Figure 7.11, shows a likely nucleation site at which crystals of phosphorus rich material have formed around a cubic structure rich in magnesium and calcium.

A B

Figure 7.26 Magnification 2300x, voltage 15.0kV, working distance 11.4mm. A: SEM secondary electron image B: SEM-EDX elemental map overlay of phosphorus, carbon and oxygen. In the center of these images appears a nucleation point around which phosphorus rich material is recrystallizing.

Figure 7.13 gives more detailed information about the nucleation shown in Figure 7.12.

In Figure 7.13 a series of elemental maps show that the phosphorus rich crystals are wrapped around a cubic structure rich in calcium and magnesium.

A B C D

Figure 7.27: Magnification 2300x, voltage 15.0kV, working distance 11.4mm. A: carbon elemental map, B: phosphorus elemental map, C: magnesium elemental map, D: calcium elemental map

Removal of Triphenyl Phosphate

Fragments from aircraft recognition models were soaked in toluene for a month. TPP is very soluble in toluene, cellulose acetate is sparingly soluble in toluene, and no other chemicals were seen in the toluene extracts although diphenyl phosphate would be soluble in toluene. The extractions conducted so far have provided products that match exactly with triphenyl phosphate as shown in the following section on Raman spectroscopy.

After a month the fragments were removed from toluene. These fragments were examined under SEM-EDX. Figure 7.14 shows images taken from these fragments.

A B C

Figure 7.28 Magnification: 950x, HV15kV, working distance 10.5. SEM-EDX images taken of a fragment from an aircraft recognition model after it had been soaked in toluene for a month. A: secondary electron image, B: carbon elemental map, C: phosphorus elemental map.

In this figure it is possible to see that the phosphorus rich material is largely removed, while fractures remain. A small aliquot of the toluene extract (about 2 drops) was dried on a microscope slide. After drying this aliquot of toluene extract, it was found using Raman spectroscopy that only triphenyl phosphate remained. This ties the veins of phosphorus rich material to TPP.

Raman of Historic Objects

It was not possible to collect a Raman spectrum of any of the aircraft recognition models due to fluorescence so chemicals were extracted from unattributed fragments using a series of different solvents and then Raman spectroscopy was used to identify them. Toluene was found to be the best solvent to extract TPP in these extractions, and highly pure triphenyl phosphate crystallized upon the evaporation of toluene from the extraction. Figure 7.15 shows the purity of the extracted TPP by comparing the Raman sample of an extraction with that of a commercial sample.

TRIPHENYL PHOSPHATE, 99+% 1.0 Rec ry stalliz ed extract toluene 780 50x 100% 100um 1 0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

Int 0.1

0.0

-0.1

-0.2

-0.3

-0.4

-0.5

-0.6

-0.7

-0.8 300 0 250 0 200 0 150 0 100 0 500 cm-1 Figure 7.29 Left: Spectra of TPP (standard) and extract from ARM. Comparison between standard TPP spectrum (top) and extracted sample from unnattributed fragment (bottom). Top spectrum taken from library of standards done on an FT-Raman system with an IR- excitation laser. Bottom spectrum taken using 780nm excitation laser on an Almega XR Dispersive Raman Spectrometer using a 10x optic on a microscope attachment of dried extract on a glass microscope slide. Right: photograph of recrystallized extract

A separate extraction experiment isolated diethyl phthalate from unattributed fragments using ethyl acetate. This chemical is often listed as a secondary plasticizer used with triphenyl phosphate (among other plasticizers). (Stannett 1950, Sully 1962) The spectra illustrating this result are provided in Figure 7.16.

Figure 7.30 Top: Diethyl phthalate (DEP), Middle: mixture of TPP and DEP extracted with ethyl acetate from ARM fragment after toluene extraction, Bottom: Triphenyl phosphate (DEP)

In the middle spectra of Figure 7.16 one can see that the extraction from the ARM fragment contains a mixture of TPP and DEP. In Figure 7.17 these peaks are assigned to the contributing chemical, labeled as DEP for diethyl phthalate, TPP for triphenyl phosphate or as

DEP+TPP for a peak coming from both species.

Figure 7.31 Labeled spectrum of ARM extract. DEP is diethyl phthalate, TPP is triphenyl phosphate and TPP + DEP peaks are those that are due to overlaps in both spectra.

By analyzing the three spectra shown in Figure 7.16 it was possible to match each of the major peaks shown in Figure 7.17. Comparing diethyl phthalate with other phthalate esters ensured that this chemical was correctly identified. It is also interesting to note that even in the dried residue, TPP is showing a peak at 718cm-1 not 726cm-1, meaning that it is in solution with

DEP. The extract spectrum was compared with other phthalate esters to confirm that the other species is that of DEP and not another phthalate ester. Figure 7.18 is an example of just such a comparison, specifically between diethyl phthalate and another volatile phthalate ester, dimethyl phthalate. It clearly shows that diethyl phthalate is the ester that is seen in the residue extracted from the ARM fragment.

Figure 7. 32 Blue: Dimethyl phthalate standard, Red: residue extracted from ARM fragment after toluene extraction, Pink: Diethyl phthalate standard

There are differences between the diethyl and dimethyl phthalates as seen in the spectra shown from 700-1260 cm-1 in Figure 4.15. Specifically at 820 cm-1 in dimethyl phthalate there is a very strong peak which is not seen in the residue extracted from the aircraft recognition model fragment. Instead there is a peak around 847cm-1. This peak is seen in diethyl phthalate, and matches very well in both location and shape. The significance of the DEP is covered in the

Discussion.

Summary of Results

XRF identified phosphorus in all of the aircraft recognition models tested to date. SEM-

EDX maps showed that there are different phases present: veins of phosphorus rich material, areas of phosphorus mixed with carbonaceous material and areas lacking phosphorus. These veins of phosphorus rich material were identified as TPP using a combination of SEM-EDX, extraction experiments and Raman Spectroscopy. Veins of phosphorus material correspond to

99 cracks in these fragments and areas of recrystallizing phosphorus rich material point towards crack initiation through the migration of triphenyl phosphate out of solid solution with cellulose acetate. Diphenyl phosphate has not been observed in any of the extractions taken from the aircraft recognition models, and diethyl phthalate a secondary plasticizer has been identified as a component within these models.

Discussion

The first step in working with the aircraft recognition models (ARMs) was the investigation of whether TPP was present within them. X-ray Fluorescence Spectroscopy (XRF) was conducted on the aircraft recognition models to test for phosphorus which it subsequently found in all models. If no phosphorus was indicated by XRF the deterioration of the aircraft recognition models would definitely be due to other factors and other case studies would have had to be found to study CA deterioration in the presence of TPP. While the XRF finding of phosphorus does not directly correlate to the presence of triphenyl phosphate, this result confirmed that presence of triphenyl phosphate was possible. The results of the XRF examination encouraged analysis into determining whether or not TPP was present in the aircraft recognition models.

SEM-EDX can map lower atomic weight elements like carbon, so it was possible to determine whether the phosphorus observed by XRF came from inorganic phosphorus compounds or organic compounds like TPP. Areas of high phosphorus content corresponded with areas of carbon content as seen by SEM-EDX meaning this could be an organic phosphorus compound like TPP. In the case of inorganic phosphorus compounds there would be little or no carbon in the same locations as the phosphorus in the EDX images. While SEM-EDX mapping

100 areas of high and low elemental content is not a truly quantitative method for elemental composition, the technique is useful in discerning areas of higher content and diversity of elements.

SEM-EDX analysis was also done on fragments taken from ARMs to map the elemental signatures on the surfaces of the fragments before and after toluene extraction. The phosphorus rich veins were seen prior to extraction and not after, which means that TPP was present in veins and crystalline structures. TPP was extracted from the fragments in toluene as confirmed by

Raman spectroscopy.

The veins of TPP correlate with cracks and this points to the separation of TPP from solid-solution with CA as the root of crack formation. Damage due to this kind of separation of one solid from a matrix is familiar in ceramics with salt degradation. What is seen in the models is the action of a plasticizer separating from the plastic matrix and solidifying. This causes the cracking and breakage of the models that is observed. This case-study agrees with the model- solution studies that this phenomenon is one of separation and recrystallization inducing deterioration. The presence of DEP, as identified by Raman spectroscopy, in the ARM fragments indicate an additional reason why the TPP is now failing. DEP was often added to increase the solubility of TPP in CA (Stannett 1950) and TPP was added to stabilize the volatility of DEP in CA. As DEP evaporates, the solubility of TPP would decrease and this would account for the separation of TPP from the CA matrix.

101

Case Study Bibliography

Garber, P. E. 1945 Special Projects Unit – duties of Head, termination status of. Department of the Navy.

Madden, O. 2011, personal communication, Museum Conservation Institute, Smithsonian Institution.

Mikesh, R.C. “Uncle Sam’s Plastic Air Force” American Aircraft Modeler September 1973.

Paul E. Garber with target kite. (Source: Smithsonian National Air and Space Museum)

Rånby, B.G. & Noe, R.W., 1961. Crystallization of Cellulose and Cellulose Derivatives from Dilute Solution. I. Growth of Single Crystals. Journal of Polymer Science, 51(155), pp.337- 347.

Remington, S. 2011, Friend or Foe? Museum: You Don't Know Who Your Enemy is Until You Recognize Him! [Online]. Available: http://collectair.com/Museum.html, March 29, 2012.

Stannett, V., 1950. Cellulose Acetate Plastics, London: Temple Press Limited.

Sully, D.B., 1962. Chapter 10: Plasticisers. In H. W. Chatfield, ed. The Science of Surface Coatings. pp. 277-301.

Zugenmaier, P., 2004. 4. Characteristics of cellulose acetates— 4.1 Characterization and physical properties of cellulose acetates. Macromolecular Symposia, 208(1), pp.81-166.

102

APPENDIX A. CHEMICALS

Acetaldehyde: CH3C(O)H, Physical Form: Liquid, Purity: puris. p.a. anhydrous, ≥99.5 (GC),

CAS# 75-07-0, Lot# BCBF4715V, Cat# 00070-100ML, Fluka Analytical, Sigma-Aldrich, 3050

Spruce Street, St. Louis, MO 63103.

Acetic Acid: CH3CO2H, Physical Form: Liquid, Purity: ACS REAGENT ≥99.7%, CAS# 64-19-

7, Lot# SHBB0668V, Cat# 320099-500ML, Sigma-Aldrich, 3050 Spruce Street, St. Louis, MO

63103.

Acetone: (CH3)2C=O, Physical Form: Liquid, Purity: HPLC Grade, UV Cutoff 330nm, CAS#

67-64-1, Lot# 030730, Fisher Scientific, Fair Lawn, NJ 07410.

Acetonitrile: CH3CN, Physical Form: Liquid, Purity: Optima® LC/MS Grade, CAS# 75-05-8,

Lot# 107461, Fisher Scientific, Fair Lawn, NJ 07410.

Ammonium Hydroxide: NH4OH, Physical Form: Liquid, Purity: ACS Grade 14.5 M, CAS#

1336-21-6, Lot# AD-10048-2, Carolina Biological Company, Burlington, NC 27215.

Amyl acetate: CH3CO2(CH2)4CH3, Physical Form: Liquid, Purity: Purified Grade, CAS# 628-

63-7, Lot# 030730, Fisher Scientific, Fair Lawn, NJ 07410.

Cellulose Acetate: Physical Form: solid powder, Purity: acetyl content 39.8%, CAS# 9004-35-7,

Cat# 083, Scientific Polymer Products, 6205 Dean Pkwy, Ontario, NY 14519.

Cellulose Acetate: Physical Form: solid flake, Fisherbrand® Sample, Date 8-26-2008, Cat No.

01-818-11.

Cellulose: (D(+)-glucose)n, Physical Form: microcrystalline solid, Purity: BAKER TLC

Reagent, CAS#9004-34-6, Lot# M32612, J.T. Baker, A Division of Mallinckrodt Baker, Inc.,

Phillipsburg, NJ 08865.

103

Diethyl ether: CH3CH2OCH2CH3, Physical Form: Liquid, Purity: 99.0% min, meets ACS spec,

CAS# 60-29-7, Lot# 102909E, VWR, 1310 Goshen Parkway, West Chester, PA 19380

Diethyl phthalate: o-(COOEt)2C6H4, Physical Form: Liquid, CAS# 84-66-2, Lot# 01, Cat# P-

183, Scientific Polymer Products, Inc., 6265 Dean Pkwy, Ontario, NY 14519.

Diphenyl phosphate: (PhO)2(HO)P=O, Physical Form: Solid, Purity: 99%, CAS# 838-85-7,

Lot# MKBH4681V, Sigma-Aldrich, Co., 3050 Spruce Street, St. Louis, MO 63103.

Ethanol: CH3CH2OH, Physical Form: Liquid, Purity: 200Proof, absolute, CAS# 64-17-5,

Pharmco™ Products Inc., 58 Vale Rd, Brookfield, CT 06804.

Ethyl Acetate: CH3CO2CH2CH3, Physical Form: Liquid, Purity: Certified ACS, CAS# 141-78-

6, Lot# 871618, Fisher Scientific, Fair Lawn, NJ 07410.

Formaldehyde solution 37% w/w: H2C=O, Physical Form: Liquid Purity: Certified ACS,

CAS# 50-00-0, contains: methanol (10-15%), water Lot# 911513, Fisher Scientific, Fair Lawn,

NJ 07410.

Formamide: NH2(H)C=O, Physical Form: Liquid, Purity: Deionized, Minimum 99.5% (GC),

CAS# 75-12-7, Lot# 044K0564, Cat# F9037-100ML, Sigma-Aldrich, 3050 Spruce Street, St.

Louis, MO 63103.

D(+)-Glucose: C6H12O6, Physical Form: Solid, Purity: reagent ACS anhydrous, CAS# 50-99-7,

Lot# B0129153, Acros, NJ.

Hexanes: mixture of isomers, Physical Form: Liquid, Purity: HPLC Grade, CAS# 110-54-3,

Lot# 983029, Fisher Scientific, Fair Lawn, NJ 07410.

Methanol: CH3OH, Physical Form: Liquid, Purity: Chromasolv® for HPLC, ≥99.9%, CAS# 67-

56-1, Batch#: 00740TC, Sigma-Aldrich, 3050 Spruce Street, St. Louis, MO 63103.

104

2-propanol: CH3-CH(OH)-CH3, Physical Form: Liquid, Purity: HPLC Grade UV Cutoff

205nm, CAS# 67-63-0, Lot# 02294, Fisher Scientific, Fair Lawn, NJ 07410.

Sodium Hydroxide: NaOH, Physical Form: Liquid, Purity: 0.9999N@25°C, CAS# 1310-73-2,

Water CAS# 7732-18-5, Lot# 0021104, VWR, 1310 Goshen Parkway, West Chester PA 19380.

Toluene: Ph-CH3, Physical Form: Liquid, Purity: HPLC Grade UV Cutoff 286nm, CAS# 108-

88-3, Lot# 022970, Fisher Scientific, Fair Lawn, NJ 07410.

Tributoxyethyl phosphate (TBOEP): (BuOCH2CH2O)3P=O,Physical Form: Liquid, CAS# 78-

51-3, Lot# 01, Cat# P-186, Scientific Polymer Products, Inc. 6265 Dean Pkwy, Ontario, NY

14519.

Tributyl phosphate (TBP): (BuO)3P=O, Physical Form: Liquid, CAS# 126-73-8, Lot# 01, Cat#

P-133, Scientific Polymer Products, Inc. 6265 Dean Pkwy, Ontario, NY 14519.

Trichloroethylene: Cl2C=CHCl¸ Physical Form: Liquid, Purity: Certified ACS, CAS# 79-01-6,

Lot# 023023, Fisher Scientific, Fair Lawn, NJ 07410

Tricresyl phosphate (TCP): (o-CH3C6H4-O)3P=O, Physical Form: Liquid, CAS# 1330-78-5,

Lot# 01, Cat# P-182, Scientific Polymer Products, Inc. 6265 Dean Pkwy, Ontario, NY 14519.

Triethyl phosphate (TEP): (EtO)3P=O, Physical Form: Liquid, Purity: ≥99.8%, CAS# 78-40-0,

Lot# MKBC8065V, Sigma-Aldrich, 3050 Spruce Street, St. Louis, MO 63103.

Triethyl phosphine oxide (TEPO): (Et)3P=O, Physical Form: Solid, Purity: 97%, CAS# 597-

50-2, Lot# MKBH3245V, Sigma-Aldrich, 3050 Spruce Street, St. Louis, MO 63103

Triethyl phosphite: (EtO)3P, Physical Form: Liquid, Purity: 98%, CAS# 122-52-1, Lot#

MKBG2273V, Sigma-Aldrich, 3050 Spruce Street, St. Louis, MO 63103.

Triphenyl phosphate (TPP): (PhO)3P=O, Physical Form: Solid, Purity: 99+%, CAS# 115-86-6,

Lot# 11701PE, Cat# 241288-50G, Sigma-Aldrich, 3050 Spruce Street, St. Louis, MO 63103.

105

Triphenyl phosphine oxide (TPPO): (Ph)3P=O, Physical Form: Solid, Purity: 98%, CAS# 791-

28-6, Lot# 1408486 50709104, Cat# T84603-25G, Sigma-Aldrich, Inc., P.O. Box 14508 St.

Louis, MO 63178.

Triphenyl phosphite: (PhO)3P, Physical Form: Solid, Purity: 97%, CAS# 101-02-0, Lot#

STBB6729, Sigma-Aldrich, 3050 Spruce Street, St. Louis, MO 63103.

Water: H2O, Physical Form: Liquid, Purity: deionized, in-house. m-Xylene: m-(CH3)2C6H4, Physical Form: Liquid, Purity: Purified Grade, CAS# 108-38-3, Lot#

872014, Fisher Scientific, Fair Lawn, NJ 07410

106

APPENDIX B. XRF

Table B.8: Aircraft Recognition Models: Summary of XRF Elements

ARM ID Mg Al Si P S K Ca Ti V Cr Mn Fe Co Cu Zn Pb As Se Br Zr 1944-30 fuselage X X X X X X X X X X X X X X X X nose paint 1944-30 fuselage X X X X X X X X X X X X X X X X paint 1944-30 X X X X X X X X X X X X X X wingtip paint 1944-31 X X X X X X X X X X X X X 1944-31 engine X X X X X X X X X X X X X X X surface paint 1944-31 wing join X X X X X X X X X X X X X 1948-85 fuselage X X X X X X X X X ? X X X X ? X nose 1948-85 tail underside X X X X X X X X X X ? X X X 1948-85 wing X X X X X X X X X X X X ? X ? X depression 1948-85 wing X X X X X X X X X X X X ? X ? X underside 1948-85 wing underside X X X X X X X X X X ? X X PR 1953-32 fuselage X X X ? X X X X X ? X nose 1953-35 tail underside X X X X X X X X X X X 1953-32 wing X X X X X X X X X X X underside Deacc Object-172 X X X X X X X X X X X X fuselage Deacc Object-172 tail X X X X X X X X X ? X X X underside Deacc Object-172 X X X X X X X X X X ? X X X wing topside Deacc Object-172 X X X X X X X X ? X X X wing topside Deacc Object-172 wing X X X X X X X X X ? X X X underside German-30 wing break X X X X X German-30 wing top X X X X X X X X ? ? X X X X X side

107

Elements

ARM ID Mg Al Si P S K Ca Ti V Cr Mn Fe Co Cu Zn Pb As Se Br Zr German-30 wing topside X X X X X X X ? X X X X X white stuff German-30 wing under X X X X X X X X X X X side Great Britian-21 X X X X X X X X X X X X ? X engine break Great Britian-21 X X X X X X X X X X X X ? X X ? X engine side Great Britian-21 X X X X X X X X X X X ? X X ? X engine tip Great Britian-24 X X X X X X X X X X wing break Great Britian-24 X X X X X X X X X X X X X wing topside Great Britian-24 wing X X X X X X X ? X ? X X underside Japan-30 interior X X X X X ? X X X ? X X X fuselage Japan-30 wing join X X X X X ? X X X X X Japan-30 wing surface X X X X X X X X X X ? X X X X paint Japan-30 wing surface X X X X X X X X ? X ? X X X X paint top Russia-3 fuselage X X X X X X X X X ? X ? X X X nose Russia-3 rail underside X ? X X X X X X X ? X ? X X X Russia-3 wing X X X X X X X ? X X X X underside

Unknown1- Fragment A X X X X X X X X ? X ? ? X

Unknown1 fuselage X X X X X X X X X X ? X X ? X X exterior Unknown1 fuselage X X X X X X X X X X interior Unknown 1 tail X X X X X X X X ? X ? X ? X underside Unknown 1 wing join X X X X X X X ? Unknown 1 wing X X X X X X X ? X ? X X X underside Unknown 2 wing X X X ? X X X X X X cracked side

108

Elements

ARM ID Mg Al Si P S K Ca Ti V Cr Mn Fe Co Cu Zn Pb As Se Br Zr Unknown 2 wing X X X ? X X X X X X cracked side gloss Unknown 2 wing uncracked X X X X X X X side Unknown 2 wing uncracked X X X ? X X X ? X X side 2 Unknown 2 wing join X X X X X X X Unknown 3 wing join X X X X X X X X X Unknown 3 wing X X X X X X X X X X ? X X X underside Unknown 3 wing X X X X X X X ? ? X ? ? X X underside 2 US-49 wing join X X X X X ? X X X US-49 wing strut X X X X X X X X X US-49 wing top side X X X X X X X X X ? X X X US-49 wing underside X X X X X X X X ? X X X USArmy-31 engine X X X X X X X X ? X X ? ? X USArmy-31 engine 2 X X X X X X X X X X ? X ? ? X USArmy-48 engine break X X X X ? X X USArmy-48 X X X X X X X ? X X X tail fuselage USArmy-48 tail X X X X X X X X ? X X underside 1 USNavy-12 fragment X X X X X X X X USNavy-12 long ? X X X X X ? X X X X X fragment USNavy-12 long fragment X X X X X X X X breakedge USNavy-14 X X X X X X X X X X X X X fuselage USNavy-14 tail break X X X X X X ? X USNavy-14 tail X X X X X X X X X X X X X underside 65 31 25 52 65 62 48 65 62 1 34 9 61 9 49 62 2 23 7 3 58 0 2 0 2 2 6 0 0 6 5 9 0 15 8 1 9 1 3 10 0

109

Table B.8 shows a breakdown of the XRF spectra collected for the aircraft recognition models.

This table has an “X” wherever the element was identified as being present, a “?” where there is a low signal to noise ratio for the peak or a “ ” when the element is not present.

110

Figure B.33 1944-30 fuselage nose paint

111

Figure B.34 1944-30 fuselage paint

112

Figure B.35 1944-30 wingtip paint

113

Figure B.36 1944-31

114

Figure B.37 1944-31 engine surface paint

115

Figure B.38 1944-31 wing join

116

Figure B.39 1948-85 fuselage nose

117

Figure B.40 1948-85 tail underside

118

Figure B.41 1948-85 wing depression

119

Figure B.42 1948-85 wing underside

120

Figure B.43 1948-85 wing underside proper right

121

Figure B.44 1953-32 fuselage nose

122

Figure B.45 1953-35 tail underside

123

Figure B.46 1953-32 wing underside

124

Figure B.47 Deaccessioned Object-172 fuselage

125

Figure B.48 Deaccessioned Object-172 tail underside

126

Figure B.49 Deaccessioned Object-172 wing topside

127

Figure B.50 Deacc Object-172 wing topside

128

Figure B.51 Deacc Object-172 wing underside

129

Figure B.52 German-30 wing break

130

Figure B.53 German-30 wing top side

131

Figure B.54 German-30 wing topside white stuff

132

Figure B.55 German-30 wing under side

133

Figure B.56 Great Britian-21 engine break

134

Figure B.57 Great Britian-21 engine side

135

Figure B.58 Great Britian-21 engine tip

136

Figure B.59 Great Britian-24 wing break

137

Figure B.60 Great Britian-24 wing topside

138

Figure B.61 Great Britian-24 wing underside

139

Figure B.62 Japan-30 interior fuselage

140

Figure B.63 Japan-30 wing join

141

Figure B.64 Japan-30 wing surface paint

142

Figure B.65 Japan-30 wing surface paint top

143

Figure B.66 Russia-3 fuselage nose

144

Figure B.67 Russia-3 tail underside

145

Figure B.68 Russia-3 wing underside

146

Figure B.69 Unknown1- Fragment A

147

Figure B.70 Unknown1 fuselage exterior

148

Figure B.71 Unknown1 fuselage interior

149

Figure B.72 Unknown 1 tail underside

150

Figure B.73 Unknown 1 wing join

151

Figure B.74 Unknown 1 wing underside

152

Figure B.75 Unknown 2 wing cracked side

153

Figure B.76 Unknown 2 wing cracked side gloss

154

Figure B.77 Unknown 2 wing without crack

155

Figure B.78 Unknown 2 wing without crack 2

156

Figure B.79 Unknown 2 wing join

157

Figure B.80 Unknown 3 wing join

158

Figure B.81 Unknown 3 wing underside

159

Figure B.82 Unknown 3 wing underside 2

160

Figure B.83 US-49 wing join

161

Figure B.84 US-49 wing strut

162

Figure B.85 US-49 wing top side

163

Figure B.86 US-49 wing underside

164

Figure B.87 USArmy-31 engine

165

Figure B.88 USArmy-31 engine 2

166

Figure B.89 USArmy-48 engine break

167

Figure B.90 USArmy-48 tail fuselage

168

Figure B.91 USArmy-48 tail underside 1

169

Figure B.92 USNavy-12 fragment

170

Figure B.93 USNavy-12 long fragment

171

Figure B.94 USNavy-12 long fragment broken edge

172

Figure B.95 USNavy-14 fuselage

173

Figure B.96 USNavy-14 tail break

174

Figure B.97 USNavy-14 tail underside

175

APPENDIX C. RAMAN SPECTROSCOPY

Figure C.1 Acetaldehyde 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 182 Figure C.2 Acetaldehyde 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 182 Figure C.3 Acetic Acid 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 184 Figure C.4 Acetic Acid 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 185 Figure C.5 Acetone 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 188 Figure C.6 Acetone 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 189 Figure C.7 Acetonitrile 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 191 Figure C.8 Acetonitrile 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 192 Figure C.9 Amyl Acetate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 195 Figure C.10 Amyl acetate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 196 Figure C.11 Cellulose 1300-100 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 198 Figure C.12 Cellulose acetate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 201 Figure C.13 Cellulose acetate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 202 Figure C.14 Diethyl phthalate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 205 Figure C.15 Diethyl phthalate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 205 Figure C.16 Diethyl phthalate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 206 Figure C.17 Ethyl Acetate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 209 Figure C.18 Ethyl acetate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 210 Figure C.19 Ethyl Ether 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 213 Figure C.20 Ethyl ether 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 214 Figure C.21 Formaldehyde 37% 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 217 Figure C.22 Formaldehyde 37% 1300-150cm-1, taken with Almega XR Dispersive Raman spectrometer...... 218 Figure C.23 Formamide 1300-150cm-1, taken with Almega XR Dispersive Raman spectrometer...... 221 Figure C.24 Formamide 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 222 Figure C.25 d-Glucose 1300-100cm-1, taken with Almega XR Dispersive Raman spectrometer...... 225 Figure C.26 d-Glucose 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 226 Figure C.27 Triphenyl phosphate in acetaldehyde 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer ...... 230 176

Figure C.28 Triphenyl phosphate in acetaldehyde 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 230 Figure C.29 Triphenyl phosphate in acetic acid 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 232 Figure C.30 Triphenyl phosphate in acetic acid 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 233 Figure C.31 Triphenyl phosphate in acetone 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 236 Figure C.32 Triphenyl phosphate in acetone 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 236 Figure C.33 Triphenyl phosphate in acetonitrile 4000-400cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 239 Figure C.34 Triphenyl phosphate in acetonitrile 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 239 Figure C.35 Triphenyl phosphate in amyl acetate 4000-400cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 241 Figure C.36 Triphenyl phosphate in amyl acetate 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 242 Figure C.37 Triphenyl phosphate in diethyl ether 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 244 Figure C.38 Triphenyl phosphate in diethyl ether 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 245 Figure C.39 Triphenyl phosphate in diethyl phthalate 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 247 Figure C.40 Triphenyl phosphate in diethyl phthalate 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 248 Figure C.41 Triphenyl phosphate in ethyl acetate 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 250 Figure C.42 Triphenyl phosphate in ethyl acetate 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 251 Figure C.43 Triphenyl phosphate in 2-propanol 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 254 177

Figure C.44 Triphenyl phosphate in 2-propanol 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 255 Figure C.45 Triphenyl phosphate in toluene 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 257 Figure C.46 Triphenyl phosphate in toluene 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 257 Figure C.47 Triphenyl phosphate in trichloroethylene 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 259 Figure C.48 Triphenyl phosphate in trichloroethylene 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 260 Figure C.49 Triphenyl phosphate (liquid) 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 262 Figure C.50 Triphenyl phosphate (liquid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 263 Figure C.51 Triphenyl phosphate (solid) 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 265 Figure C.52 Triphenyl phosphate (solid) 900-600 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 266 Figure C.53 Top: Diethyl phthalate standard, Middle: Aircraft recognition model residue after ethyl acetate has been evaporated, Bottom: Triphenyl phosphate, taken with Almega XR Dispersive Raman spectrometer, 3500-150 cm-1...... 268 Figure C.54 Comparison between Blue: Dimethyl phthalate, Red: Aircraft recognition model residue and Pink: diethyl phthalate, 1250-720cm-1, Taken with Almega XR Dispersive Raman spectrometer...... 269 Figure C.55 Identification of all the contribution of the peaks seen in the residue removed from the aircraft recognition models, 3500-150 cm-1 Taken with Almega XR Dispersive Raman spectrometer...... 270 Figure C.56 TPP recrystallized in acetone spot 1 (solution) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 272 Figure C.57 TPP recrystallized in acetone spot 1 (solution) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 273 Figure C.58 TPP recrystallized in acetone spot 2 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 274 Figure C.59 TPP recrystallized in acetone spot 2 liquid solidifying 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 275 178

Figure C.60 TPP recrystallized in acetone spot 3 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 276 Figure C.61 TPP recrystallized in acetone spot 3 (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 277 Figure C.62 TPP recrystallized in acetone spot 4 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 278 Figure C.63 TPP recrystallized in acetone spot 4 (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 279 Figure C.64 TPP recrystallized in acetone spot 5 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 280 Figure C.65 TPP recrystallized in acetone spot 5 (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 281 Figure C.66 TPP recrystallized in acetone spot 6 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 282 Figure C.67 TPP recrystallized in acetone spot 6 (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 283 Figure C.68 TPP recrystallized in acetonitrile spot 2 (partial crystallization) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 284 Figure C.69 TPP recrystallized in hexanes (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 285 Figure C.70 TPP recrystallized in hexanes (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 286 Figure C.71 TPP recrystallized in 2-propanol spot 1 (solution) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 287 Figure C.72 TPP recrystallized in 2-propanol spot 1 (solution) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 288 Figure C.73 TPP recrystallized in 2-propanol spot 2 (mostly crystallized) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 289 Figure C.74 TPP recrystallized in 2-propanol spot 2 (mostly crystallized) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 290 Figure C.75 TPP recrystallized in 2-propanol spot 3 (mostly crystallized) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 291 179

Figure C.76 TPP recrystallized in 2-propanol spot 3 (mostly crystallized) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 292 Figure C.77 Comparison of two time points:TPP recrystallized in 2-propanol spot 2 (solution phase) and 3 (mostly crystallized) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 293 Figure C.78 TPP recrystallized in toluene (solution phase) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 294 Figure C.79 TPP recrystallized in toluene (solution phase) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer...... 295 Figure C.80 Tributoxyethyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 297 Figure C.81 Tributoxyethyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 298 Figure C.82 Tributyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 299 Figure C.83 Tributyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 300 Figure C.84 Tricresyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 301 Figure C.85 Tricresyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 302 Figure C.86 Triethyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 303 Figure C.87 Triethyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 304 Figure C.88 Triethyl phosphite 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 305 Figure C.89 Triethyl phosphite 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer...... 306 Figure C.90 Triethyl phosphine oxide 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 307 Figure C.91 Triethyl phosphine oxide 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 308 Figure C.92 Triphenyl phosphate 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 309 Figure C.93 Triphenyl phosphate 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 310 Figure C.94 Triphenyl phosphite 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 311 Figure C.95 Triphenyl phosphite 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 312 Figure C.96 Triphenyl phosphine oxide 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 313 Figure C.97 Triphenyl phosphine oxide 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer...... 314

Observing instrumental shift for dispersive Raman spectroscopy unit

Table C.9 Measurement of TPP peak by Dispersive Raman Measurement TPP Peak 1 726.00 180

2 725.88 3 726.16 4 726.06 5 725.99 6 726.19 7 725.98 8 726.38 9 726.00 10 726.19 11 726.61 Average TPP 726.13 Standard 0.21 Deviation This experiment was conducted to determine the fluctuation of the TPP 726cm-1 might be as measured by the dispersive Raman instrument in the course of a day. These spectra were collected alternating with between collecting other spectra. 181

Chemical Spectra: Pure

182

Figure C.98 Acetaldehyde 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer.

Figure C.99 Acetaldehyde 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

183

Acetaldehyde, taken with Almega XR Dispersive Raman spectrometer. Comments: Acetaldehyde from Laser polarization: Parallel Cosmic ray threshold: Low manufacturer opened 9 2011 Grating: 1200 lines/mm Bench Serial Number: AGE0200212 Operator: Molly McGath Spectrograph aperture: 25 µm pinhole Smart background used Sample Form: Liquid Camera temperature: -49 C Raw data saved with spectrum. CCD rows binned: 6-250 Comment added on Thu Sep 15 DATA DESCRIPTION CCD binning: On chip (auto row 16:41:22 2011 (GMT-05:00) Number of points: 2491 select) Custom info 1 added on Thu Sep 15 X-axis: Raman shift (cm-1) Polarization analyzer: Out 16:41:22 2011 (GMT-05:00) Y-axis: Raman intensity Custom info 2 added on Thu Sep 15 First X value: 90.4717 COLLECTION ERRORS 16:41:22 2011 (GMT-05:00) Last X value: 1290.9414 Errors During Sample Collection Straight Line on Mon Aug 27 Raman laser frequency: 12820.7627 Number of Rejected Scans:0 22:05:39 2012 (GMT-05:00) Data spacing: 0.482116 Error Types: None Data format: Raman intensity From 227.0030 to 222.1124 DATA COLLECTION DATA PROCESSING HISTORY INFORMATION Collect Sample EXPERIMENT INFORMATION: Exposure time: 3.00 sec Background collected: Mon Experiment filename: C:\My Number of exposures: 512 Jun 20 11:30:45 2011 (GMT-05:00) Documents\OMNIC\VRParam\default Number of background exposures: Final format: Shifted spectrum (cm- .exp 512 1)\ Experiment title: Almega Center wavelength: 827.1 nm Experiment accessory: SPECTROMETER DESCRIPTION Calibrated: Mon Aug 29 12:27:31 Spectrometer: Almega 2011 (GMT-05:00) SPECTRAL QUALITY RESULTS: Laser: 780 nm Resolution: 0.9642 Raman shift CCD overflow test passed Laser power level: 100% (cm-1) from 90.4717 to 1290.9414 Sample burning test passed 184

Figure C.100 Acetic Acid 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. 185

Figure C.101 Acetic Acid 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

186

Acetic Acid taken with Almega XR Dispersive Raman spectrometer. Comments: Acetic Acid Sigma Exposure time: 3.00 sec Polarization analyzer: Out

Aldrich opened 09/2011 Number of exposures: 512

Operator: Molly McGath Number of background exposures: COLLECTION ERRORS

Sample Form: Liquid 512 Errors During Sample Collection

Number of Rejected Scans:0

DATA DESCRIPTION SPECTROMETER DESCRIPTION Error Types: None

Number of points: 2491 Spectrometer: Almega

X-axis: Raman shift (cm-1) Laser: 780 nm DATA PROCESSING HISTORY

Y-axis: Raman intensity Laser power level: 100% Collect Sample

First X value: 90.4717 Laser polarization: Parallel Background collected: Mon

Last X value: 1290.9414 Grating: 1200 lines/mm Jun 20 11:30:45 2011 (GMT-05:00)

Raman laser frequency: 12820.7627 Spectrograph aperture: 25 µm pinhole Final format: Shifted spectrum (cm-

Data spacing: 0.482116 Camera temperature: -49 C 1)

CCD rows binned: 6-250 Center wavelength: 827.1 nm

DATA COLLECTION CCD binning: On chip (auto row Calibrated: Mon Aug 29 12:27:31

INFORMATION select) 2011 (GMT-05:00) 187

Resolution: 0.9642 Raman shift Custom info 2 added on Thu Sep 15 EXPERIMENT INFORMATION:

(cm-1) from 90.4717 to 1290.9414 17:22:14 2011 (GMT-05:00) Experiment filename: C:\My

Cosmic ray threshold: Low Straight Line on Mon Aug 27 Documents\OMNIC\VRParam\default

Bench Serial Number: AGE0200212 22:06:36 2012 (GMT-05:00) exp

Smart background used Data format: Raman intensity Experiment title: Almega

Raw data saved with spectrum. From 227.1422 to 221.8525 Experiment accessory:

Comment added on Thu Sep 15 Spectrum converted to shifted Raman

17:22:14 2011 (GMT-05:00) X-axis Mon Aug 27 22:06:37 2012 SPECTRAL QUALITY RESULTS:

Custom info 1 added on Thu Sep 15 (GMT-05:00) CCD overflow test passed

17:22:14 2011 (GMT-05:00) Sample burning test passed 188

Figure C.102 Acetone 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. 189

Figure C.103 Acetone 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

190

Acetone taken with Almega XR Dispersive Raman spectrometer Comments: Acetone: HPLC Grade Laser polarization: Parallel Raw data saved with spectrum. UV Cutoff 330nm Fischer Scientific. Grating: 1200 lines/mm Lot No. 030730. Fair Lawn, New Spectrograph aperture: 25 µm pinhole Comment added on Mon Aug 22 Jersey 07410 (201) 796-7100. CAS Camera temperature: -49 C 14:47:40 2011 (GMT-05:00) 67-64-1 CCD rows binned: 6-250 Custom info 1 added on Mon Aug 22 Operator: Molly McGath CCD binning: On chip (auto row 14:47:40 2011 (GMT-05:00) Sample Form: Liquid select) Custom info 2 added on Mon Aug 22 Polarization analyzer: Out 14:47:40 2011 (GMT-05:00) DATA DESCRIPTION Straight Line on Mon Aug 27 Number of points: 2492 COLLECTION ERRORS 22:06:56 2012 (GMT-05:00) X-axis: Raman shift (cm-1) Errors During Sample Collection Data format: Raman intensity Y-axis: Raman intensity Number of Rejected Scans:0 From 228.6062 to 223.6162 First X value: 91.5156 Error Types: None Spectrum converted to shifted Last X value: 1292.4678 RamanX-axis Mon Aug 27 22:07:02 Raman laser frequency: 12820.8428 DATA PROCESSING HISTORY 2012 (GMT-05:00) Data spacing: 0.482116 Collect Sample Background collected: Mon Jun 20 EXPERIMENT INFORMATION: DATA COLLECTION 11:30:45 2011 (GMT-05:00) Experiment filename: C:\My INFORMATION Final format: Shifted spectrum (cm- Documents\Omnic\VRParam\default. Exposure time: 1.00 sec 1) exp Number of exposures: 256 Center wavelength: 827.1 nm Experiment title: Almega Number of background exposures: Calibrated: Tue Aug 16 16:10:51 Experiment accessory: 512 2011 (GMT-05:00) Resolution: 0.9642 Raman shift (cm- SPECTRAL QUALITY RESULTS: SPECTROMETER DESCRIPTION 1) from 91.5156 to 1292.4678 CCD overflow test passed Spectrometer: Almega Cosmic ray threshold: Low Sample burning test passed Laser: 780 nm Bench Serial Number: AGE0200212 Laser power level: 100% Smart background used

191

Figure C.104 Acetonitrile 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. 192

Figure C.105 Acetonitrile 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer

. 193

Acetonitrile taken with Almega XR Dispersive Raman spectrometer 194

Comments: Acetone: HPLC Grade Laser power level: 100% Smart background used UV Cutoff 330nm Fischer Scientific. Laser polarization: Parallel Raw data saved with spectrum. Lot No. 030730. Fair Lawn, New Grating: 1200 lines/mm Comment added on Mon Aug 22 Jersey 07410 (201) 796-7100. CAS Spectrograph aperture: 25 µm pinhole 14:47:40 2011 (GMT-05:00) 67-64-1 Camera temperature: -49 C Custom info 1 added on Mon Aug 22 Operator: Molly McGath CCD rows binned: 6-250 14:47:40 2011 (GMT-05:00) Sample Form: Liquid CCD binning: On chip (auto row Custom info 2 added on Mon Aug 22 select) 14:47:40 2011 (GMT-05:00) DATA DESCRIPTION Polarization analyzer: Out Straight Line on Mon Aug 27 Number of points: 2492 COLLECTION ERRORS 22:06:56 2012 (GMT-05:00) X-axis: Raman shift (cm-1) Errors During Sample Collection Data format: Raman intensity Y-axis: Raman intensity Number of Rejected Scans:0 From 228.6062 to 223.6162 First X value: 91.5156 Error Types: None Spectrum converted to shifted Raman Last X value: 1292.4678 X-axis Mon Aug 27 22:07:02 2012 Raman laser frequency: 12820.8428 DATA PROCESSING HISTORY (GMT-05:00) Data spacing: 0.482116 Collect Sample Background collected: Mon Jun 20 EXPERIMENT INFORMATION: DATA COLLECTION 11:30:45 2011 (GMT-05:00) Experiment filename: C:\My INFORMATION Final format: Shifted spectrum (cm- Documents\Omnic\VRParam\default. Exposure time: 1.00 sec 1) exp Number of exposures: 256 Center wavelength: 827.1 nm Experiment title: Almega Number of background exposures: Calibrated: Tue Aug 16 16:10:51 Experiment accessory: 512 2011 (GMT-05:00) Resolution: 0.9642 Raman shift (cm- SPECTRAL QUALITY RESULTS: SPECTROMETER DESCRIPTION 1) from 91.5156 to 1292.4678 CCD overflow test passed Spectrometer: Almega Cosmic ray threshold: Low Sample burning test passed Laser: 780 nm Bench Serial Number: AGE0200212 195

Figure C.106 Amyl Acetate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. 196

Figure C.107 Amyl acetate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

197

Amyl acetate taken with Almega XR Dispersive Raman spectrometer. Comments: Amyl Acetate (Pear Oil or Grating: 1200 lines/mm Raw data saved with spectrum. Banana Oil) Purified Grade, Fisher Spectrograph aperture: 25 µm pinhole Scientific Lot No. 871716 Camera temperature: -49 C Comment added on Mon Aug 22 Operator: Molly McGath CCD rows binned: 6-250 16:21:45 2011 (GMT-05:00) Sample: Liquid CCD binning: On chip (auto row Custom info 1 added on Mon Aug 22 select) 16:21:45 2011 (GMT-05:00) DATA DESCRIPTION Polarization analyzer: Out Custom info 2 added on Mon Aug 22 Number of points: 2492 16:21:45 2011 (GMT-05:00) X-axis: Raman shift (cm-1) COLLECTION ERRORS Straight Line on Mon Aug 27 Y-axis: Raman intensity Errors During Sample Collection 22:08:36 2012 (GMT-05:00) First X value: 91.5156 Number of Rejected Scans:0 Data format: Raman intensity Last X value: 1292.4678 Error Types: None From 228.6077 to 223.6502 Raman laser frequency: 12820.8428 Data spacing: 0.482116 DATA PROCESSING HISTORY Spectrum converted to shifted Raman Collect Sample X-axis Mon Aug 27 22:08:42 2012 DATA COLLECTION Background collected: Mon Jun 20 (GMT-05:00) INFORMATION 11:30:45 2011 (GMT-05:00) Exposure time: 2.00 sec Final format: Shifted spectrum (cm- EXPERIMENT INFORMATION: Number of exposures: 256 1) Experiment filename: C:\My Number of background exposures: Center wavelength: 827.1 nm Documents\Omnic\VRParam\default. 512 Calibrated: Tue Aug 16 exp 16:10:51 2011 (GMT-05:00) Experiment title: Almega SPECTROMETER DESCRIPTION Resolution: 0.9642 Raman shift Experiment accessory: Spectrometer: Almega (cm-1) from 91.5156 to 1292.4678 Laser: 780 nm Cosmic ray threshold: Low SPECTRAL QUALITY RESULTS: Laser power level: 100% Bench Serial Number: AGE0200212 CCD overflow test passed Laser polarization: Parallel Smart background used Sample burning test passed 198

Figure C.108 Cellulose 1300-100 cm-1, taken with Almega XR Dispersive Raman spectrometer. 199

Cellulose taken with Almega XR Dispersive Raman spectrometer. Comments: Cellulose Pure Number of exposures: 256 Polarization analyzer: Out

Operator: Molly McGath Number of background exposures:

Sample Form: Solid Powder 512 COLLECTION ERRORS

Errors During Sample Collection

DATA DESCRIPTION SPECTROMETER DESCRIPTION Number of Rejected Scans:0

Number of points: 2492 Spectrometer: Almega Error Types: None

X-axis: Raman shift (cm-1) Laser: 780 nm

Y-axis: Raman intensity Laser power level: 100% DATA PROCESSING HISTORY

First X value: 91.5156 Laser polarization: Parallel Collect Sample

Last X value: 1292.4678 Grating: 1200 lines/mm Background collected: Mon Jun 20

Raman laser frequency: 12820.8428 Spectrograph aperture: 100 µm 11:30:45 2011 (GMT-05:00)

Data spacing: 0.482116 pinhole Final format: Shifted spectrum (cm-

Camera temperature: -49 C 1)

DATA COLLECTION CCD rows binned: 6-250 Center wavelength: 827.1 nm

INFORMATION CCD binning: On chip (auto row Calibrated: Tue Aug 16

Exposure time: 10.00 sec select) 16:10:51 2011 (GMT-05:00) 200

Resolution: 0.9642 Raman shift Custom info 2 added on Mon Aug 22 EXPERIMENT INFORMATION:

(cm-1) from 91.5156 to 1292.4678 17:55:57 2011 (GMT-05:00) Experiment filename: C:\My

Cosmic ray threshold: Low Straight Line on Mon Aug 27 Documents\Omnic\VRParam\default.

Bench Serial Number: AGE0200212 22:25:22 2012 (GMT-05:00) exp

Smart background used Data format: Raman intensity Experiment title: Almega

Raw data saved with spectrum. From 228.5876 to 223.7740 Experiment accessory:

Comment added on Mon Aug 22

17:55:57 2011 (GMT-05:00) Spectrum converted to shifted Raman SPECTRAL QUALITY RESULTS:

Custom info 1 added on Mon Aug 22 X-axis Mon Aug 27 22:25:22 2012 CCD overflow test passed

17:55:57 2011 (GMT-05:00) (GMT-05:00) Sample burning test passed

201

Figure C.109 Cellulose acetate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. 202

Figure C.110 Cellulose acetate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer. 203

Cellulose acetate taken with Almega XR Dispersive Raman spectrometer. Comments: cellulose acetate solid Exposure time: 6.00 sec Polarization analyzer: Out powder Number of exposures: 256

Operator: Molly McGath Number of background exposures: COLLECTION ERRORS

Sample Form: Solid Powder 512 Errors During Sample Collection

Number of Rejected Scans:0

DATA DESCRIPTION SPECTROMETER DESCRIPTION Error Types: None

Number of points: 2491 Spectrometer: Almega

X-axis: Raman shift (cm-1) Laser: 780 nm DATA PROCESSING HISTORY

Y-axis: Raman intensity Laser power level: 100% Collect Sample

First X value: 90.4717 Laser polarization: Parallel Background collected: Mon Jun 20

Last X value: 1290.9414 Grating: 1200 lines/mm 11:30:45 2011 (GMT-05:00)

Raman laser frequency: 12820.7627 Spectrograph aperture: 25 µm pinhole Final format: Shifted spectrum (cm-

Data spacing: 0.482116 Camera temperature: -49 C 1)

CCD rows binned: 6-250 Center wavelength: 827.1 nm

DATA COLLECTION CCD binning: On chip (auto row Calibrated: Mon Aug 29

INFORMATION select) 12:27:31 2011 (GMT-05:00) 204

Resolution: 0.9642 Raman shift Custom info 1 added on Mon Sep 19 Experiment title: Almega

(cm-1) from 90.4717 to 1290.9414 13:25:24 2011 (GMT-05:00) Experiment accessory:

Cosmic ray threshold: Low Custom info 2 added on Mon Sep 19

Bench Serial Number: AGE0200212 13:25:24 2011 (GMT-05:00) SPECTRAL QUALITY RESULTS:

Smart background used CCD overflow test passed

Raw data saved with spectrum. EXPERIMENT INFORMATION: Sample burning test passed

Comment added on Mon Sep 19 Experiment filename: C:\My

13:25:24 2011 (GMT-05:00) Documents\OMNIC\VRParam\default

.exp

205

Figure C.111 Diethyl phthalate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer.

Figure C.112 Diethyl phthalate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. 206

Figure C.113 Diethyl phthalate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer. 207

Diethyl phthalate taken with Almega XR Dispersive Raman spectrometer. Comments: High resolution scan. Number of exposures: 256

Operator: Molly McGath Number of background exposures: COLLECTION ERRORS

Sample Form: Liquid 512 Errors During Sample Collection

Number of Rejected Scans:0

DATA DESCRIPTION SPECTROMETER DESCRIPTION Error Types: None

Number of points: 2491 Spectrometer: Almega

X-axis: Raman shift (cm-1) Laser: 780 nm DATA PROCESSING HISTORY

Y-axis: Raman intensity Laser power level: 100% Collect Sample

First X value: 90.5518 Laser polarization: Parallel Background collected: Mon Jun 20

Last X value: 1291.0215 Grating: 1200 lines/mm 11:30:45 2011 (GMT-05:00)

Raman laser frequency: 12820.8428 Spectrograph aperture: 25 µm pinhole Final format: Shifted spectrum (cm-

Data spacing: 0.482116 Camera temperature: -49 C 1)

CCD rows binned: 6-250 Center wavelength: 827.1 nm

DATA COLLECTION CCD binning: On chip (auto row Calibrated: Mon Aug 29

INFORMATION select) 12:27:31 2011 (GMT-05:00)

Exposure time: 3.00 sec Polarization analyzer: Out 208

Resolution: 0.9642 Raman shift Custom info 1 added on Fri Sep 02 Experiment title: Almega

(cm-1) from 90.5518 to 1291.0215 14:02:25 2011 (GMT-05:00) Experiment accessory:

Cosmic ray threshold: Low Custom info 2 added on Fri Sep 02

Bench Serial Number: AGE0200212 14:02:25 2011 (GMT-05:00) SPECTRAL QUALITY RESULTS:

Smart background used CCD overflow test passed

Raw data saved with spectrum. EXPERIMENT INFORMATION: Sample burning test passed

Comment added on Fri Sep 02 Experiment filename: C:\My

14:02:25 2011 (GMT-05:00) Documents\OMNIC\VRParam\default

.exp

209

Figure C.114 Ethyl Acetate 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. 210

Figure C.115 Ethyl acetate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer. 211

Ethyl acetate taken with Almega XR Dispersive Raman spectrometer. Comments: Ethyl Acetate Fischer Exposure time: 2.00 sec Polarization analyzer: Out

Scientific Lot No. 871618 Number of exposures: 256

Operator: Molly McGath Number of background exposures: COLLECTION ERRORS

Sample Form: Liquid 512 Errors During Sample Collection

Number of Rejected Scans:0

DATA DESCRIPTION SPECTROMETER DESCRIPTION Error Types: None

Number of points: 2492 Spectrometer: Almega

X-axis: Raman shift (cm-1) Laser: 780 nm DATA PROCESSING HISTORY

Y-axis: Raman intensity Laser power level: 100% Collect Sample

First X value: 91.5156 Laser polarization: Parallel Background collected: Mon Jun 20

Last X value: 1292.4678 Grating: 1200 lines/mm 11:30:45 2011 (GMT-05:00)

Raman laser frequency: 12820.8428 Spectrograph aperture: 25 µm pinhole Final format: Shifted spectrum (cm-

Data spacing: 0.482116 Camera temperature: -49 C 1)

CCD rows binned: 6-250 Center wavelength: 827.1 nm

DATA COLLECTION CCD binning: On chip (auto row Calibrated: Tue Aug 16

INFORMATION select) 16:10:51 2011 (GMT-05:00) 212

Resolution: 0.9642 Raman shift Custom info 2 added on Mon Aug 22 EXPERIMENT INFORMATION:

(cm-1) from 91.5156 to 1292.4678 16:25:00 2011 (GMT-05:00) Experiment filename: C:\My

Cosmic ray threshold: Low Straight Line on Mon Aug 27 Documents\Omnic\VRParam\default.

Bench Serial Number: AGE0200212 22:47:28 2012 (GMT-05:00) exp

Smart background used Data format: Raman intensity Experiment title: Almega

Raw data saved with spectrum. From 228.8151 to 223.5048 Experiment accessory:

Comment added on Mon Aug 22 Spectrum converted to shifted Raman

16:25:00 2011 (GMT-05:00) X-axis Mon Aug 27 22:47:33 2012 SPECTRAL QUALITY RESULTS:

Custom info 1 added on Mon Aug 22 (GMT-05:00) CCD overflow test passed

16:25:00 2011 (GMT-05:00) Sample burning test passed

213

Figure C.116 Ethyl Ether 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. 214

Figure C.117 Ethyl ether 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

215

Ethyl ether taken with Almega XR Dispersive Raman spectrometer. Comments: Ethyl Ether alone Number of exposures: 256

Operator: Molly McGath Number of background exposures: COLLECTION ERRORS

Sample Form: Liquid 512 Errors During Sample Collection

Number of Rejected Scans:0

DATA DESCRIPTION SPECTROMETER DESCRIPTION Error Types: None

Number of points: 2491 Spectrometer: Almega

X-axis: Raman shift (cm-1) Laser: 780 nm DATA PROCESSING HISTORY

Y-axis: Raman intensity Laser power level: 100% Collect Sample

First X value: 90.5518 Laser polarization: Parallel Background collected: Mon Jun 20

Last X value: 1291.0215 Grating: 1200 lines/mm 11:30:45 2011 (GMT-05:00)

Raman laser frequency: 12820.8428 Spectrograph aperture: 25 µm pinhole Final format: Shifted spectrum (cm-

Data spacing: 0.482116 Camera temperature: -49 C 1)

CCD rows binned: 6-250 Center wavelength: 827.1 nm

DATA COLLECTION CCD binning: On chip (auto row Calibrated: Mon Aug 29

INFORMATION select) 12:27:31 2011 (GMT-05:00)

Exposure time: 4.00 sec Polarization analyzer: Out 216

Resolution: 0.9642 Raman shift Custom info 2 added on Wed Aug 31 EXPERIMENT INFORMATION:

(cm-1) from 90.5518 to 1291.0215 16:39:29 2011 (GMT-05:00) Experiment filename: C:\My

Cosmic ray threshold: Low Straight Line on Mon Aug 27 Documents\OMNIC\VRParam\default

Bench Serial Number: AGE0200212 22:47:14 2012 (GMT-05:00) .exp

Smart background used Data format: Raman intensity Experiment title: Almega

Raw data saved with spectrum. From 227.1944 to 221.9929 Experiment accessory:

Comment added on Wed Aug 31 Spectrum converted to shifted Raman

16:39:29 2011 (GMT-05:00) X-axis Mon Aug 27 22:47:17 2012 SPECTRAL QUALITY RESULTS:

Custom info 1 added on Wed Aug 31 (GMT-05:00) CCD overflow test passed

16:39:29 2011 (GMT-05:00) Sample burning test passed

217

Figure C.118 Formaldehyde 37% 1300-150 cm-1, taken with Almega XR Dispersive Raman spectrometer. 218

Figure C.119 Formaldehyde 37% 1300-150cm-1, taken with Almega XR Dispersive Raman spectrometer.

219

Formaldehyde 37% in water taken with Almega XR Dispersive Raman spectrometer. Comments: Formaldehyde Solution DATA COLLECTION CCD binning: On chip (auto row

37% w/w Fisher Scientific F79-500 INFORMATION select)

Lot No. 911513 Exposure time: 2.00 sec Polarization analyzer: Out

Operator: Molly McGath Number of exposures: 256

Sample Form: Liquid Number of background exposures: COLLECTION ERRORS

512 Errors During Sample Collection

DATA DESCRIPTION Number of Rejected Scans:0

Number of points: 2492 SPECTROMETER DESCRIPTION Error Types: None

X-axis: Raman shift (cm-1) Spectrometer: Almega

Y-axis: Raman intensity Laser: 780 nm DATA PROCESSING HISTORY

First X value: 91.5156 Laser power level: 100% Collect Sample

Last X value: 1292.4678 Laser polarization: Parallel Background collected: Mon Jun 20

Raman laser frequency: 12820.8428 Grating: 1200 lines/mm 11:30:45 2011 (GMT-05:00)

Data spacing: 0.482116 Spectrograph aperture: 25 µm pinhole Final format: Shifted spectrum (cm-

Camera temperature: -49 C 1)

CCD rows binned: 6-250 220

Center wavelength: 827.1 nm Custom info 1 added on Mon Aug 22

Calibrated: Tue Aug 16 16:27:52 2011 (GMT-05:00) EXPERIMENT INFORMATION:

16:10:51 2011 (GMT-05:00) Custom info 2 added on Mon Aug 22 Experiment filename: C:\My

Resolution: 0.9642 Raman shift 16:27:52 2011 (GMT-05:00) Documents\Omnic\VRParam\default.

(cm-1) from 91.5156 to 1292.4678 Straight Line on Mon Aug 27 exp

Cosmic ray threshold: Low 23:03:24 2012 (GMT-05:00) Experiment title: Almega

Bench Serial Number: AGE0200212 Data format: Raman intensity Experiment accessory:

Smart background used From 228.4577 to 223.5837

Raw data saved with spectrum. Spectrum converted to shifted Raman SPECTRAL QUALITY RESULTS:

Comment added on Mon Aug 22 X-axis Mon Aug 27 23:03:27 2012 CCD overflow test passed

16:27:52 2011 (GMT-05:00) (GMT-05:00) Sample burning test passed

221

Figure C.120 Formamide 1300-150cm-1, taken with Almega XR Dispersive Raman spectrometer. 222

Figure C.121 Formamide 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

223

Formamide taken with Almega XR Dispersive Raman spectrometer. Comments: Number of exposures: 256

Operator: Molly McGath Number of background exposures: COLLECTION ERRORS

Sample Form: Liquid 512 Errors During Sample Collection

Number of Rejected Scans:0

DATA DESCRIPTION SPECTROMETER DESCRIPTION Error Types: None

Number of points: 2492 Spectrometer: Almega

X-axis: Raman shift (cm-1) Laser: 780 nm DATA PROCESSING HISTORY

Y-axis: Raman intensity Laser power level: 100% Collect Sample

First X value: 91.5156 Laser polarization: Parallel Background collected: Mon Jun 20

Last X value: 1292.4678 Grating: 1200 lines/mm 11:30:45 2011 (GMT-05:00)

Raman laser frequency: 12820.8428 Spectrograph aperture: 25 µm pinhole Final format: Shifted spectrum (cm-

Data spacing: 0.482116 Camera temperature: -49 C 1)

CCD rows binned: 6-250 Center wavelength: 827.1 nm

DATA COLLECTION CCD binning: On chip (auto row Calibrated: Tue Aug 16

INFORMATION select) 16:10:51 2011 (GMT-05:00)

Exposure time: 10.00 sec Polarization analyzer: Out 224

Resolution: 0.9642 Raman shift Data format: Raman intensity Experiment accessory:

(cm-1) from 91.5156 to 1292.4678 From 228.5412 to 223.5899

Cosmic ray threshold: Low SPECTRAL QUALITY RESULTS:

Bench Serial Number: AGE0200212 EXPERIMENT INFORMATION: CCD overflow test passed

Smart background used Experiment filename: C:\My Sample burning test passed

Raw data saved with spectrum. Documents\Omnic\VRParam\default.

Straight Line on Mon Aug 27 exp

23:03:12 2012 (GMT-05:00) Experiment title: Almega

225

Figure C.122 d-Glucose 1300-100cm-1, taken with Almega XR Dispersive Raman spectrometer. 226

Figure C.123 d-Glucose 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

227 d-Glucose taken with Almega XR Dispersive Raman spectrometer. 228

Comments: d-Glucose at hires Laser: 780 nm Final format: Shifted spectrum (cm- Operator: Molly McGath Laser power level: 100% 1) Sample Form: Solid Powder Laser polarization: Parallel Center wavelength: 827.1 nm Grating: 1200 lines/mm Calibrated: Mon Aug 29 DATA DESCRIPTION Spectrograph aperture: 100 µm 12:27:31 2011 (GMT-05:00) Number of points: 2491 pinhole Resolution: 0.9642 Raman shift X-axis: Raman shift (cm-1) Camera temperature: -49 C (cm-1) from 90.4717 to 1290.9414 Y-axis: Raman intensity CCD rows binned: 6-250 Cosmic ray threshold: Low First X value: 90.4717 CCD binning: On chip (auto row Bench Serial Number: AGE0200212 Last X value: 1290.9414 select) Smart background used Raman laser frequency: 12820.7627 Polarization analyzer: Out Raw data saved with spectrum. Data spacing: 0.482116 COLLECTION ERRORS EXPERIMENT INFORMATION: DATA COLLECTION Errors During Sample Collection Experiment filename: C:\My INFORMATION Number of Rejected Scans:0 Documents\OMNIC\VRParam\default Exposure time: 3.00 sec Error Types: None .exp Number of exposures: 256 Experiment title: Almega Number of background exposures: DATA PROCESSING HISTORY Experiment accessory: 512 Collect Sample Background collected: Mon Jun 20 SPECTRAL QUALITY RESULTS: SPECTROMETER DESCRIPTION 11:30:45 2011 (GMT-05:00) CCD overflow test passed Spectrometer: Almega Sample burning test passed

229

Chemical Spectra: Mixture TPP with Solvent 20:80 w/w %

230

Figure C.124 Triphenyl phosphate in acetaldehyde 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer

Figure C.125 Triphenyl phosphate in acetaldehyde 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 231

Triphenyl phosphate in acetaldehyde taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta- data. Number of sample scans: 1024 Y-axis: Raman intensity Sample gain: 1.0 Collection length: 2135.72 sec First X value: 98.2844 High pass filter: 200.0000 Resolution: 4.000 Last X value: 3700.7178 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 16672 Data spacing: 1.928498 COLLECTION ERRORS Number of FFT points: 16384 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 4.000 from 98.2844 to DATA DESCRIPTION Digitizer bits: 24 3700.7178 Number of poitns: 1869 Mirror velocity: 0.3165 Laser power at sample 0.504W X-axis: Raman shift (cm-1) Aperture: 59.00 232

Figure C.126 Triphenyl phosphate in acetic acid 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 233

Figure C.127 Triphenyl phosphate in acetic acid 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 234

Triphenyl phosphate in acetic acid taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta-data. Number of sample scans: 1024 Y-axis: Raman intensity Sample gain: 1.0 Collection length: 5632.04 sec First X value: 99.7308 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3700.2354 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 99.7308 to DATA DESCRIPTION Digitizer bits: 24 3700.2354 Number of points: 7469 Mirror velocity: 0.3165 Laser power at sample 1.713W X-axis: Raman shift (cm-1) Aperture: 14.00

235

236

Figure C.128 Triphenyl phosphate in acetone 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

Figure C.129 Triphenyl phosphate in acetone 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 237

Triphenyl phosphate in acetone taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta-data. Number of sample scans: 1024 Y-axis: Raman intensity Sample gain: 1.0 Collection length: 5009.21 sec First X value: 99.7308 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3700.2354 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 99.7308 to DATA DESCRIPTION Digitizer bits: 24 3700.2354 Number of points: 7469 Mirror velocity: 0.3165 Laser power at sample 1.713W X-axis: Raman shift (cm-1) Aperture: 14.00

238

239

Figure C.130 Triphenyl phosphate in acetonitrile 4000-400cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

Figure C.131 Triphenyl phosphate in acetonitrile 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 240

Triphenyl phosphate in acetonitrile taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta-data. Number of sample scans: 1024 Source: Off Collection length: 21728.71 sec Detector: InGaAs Resolution: 1.000 Smart Accessory ID: 03 Levels of zero filling: 0 Beamsplitter: CaF2 Number of scan points: 41248 Sample spacing: 1.0000 Number of FFT points: 65536 Digitizer bits: 24 Laser Frequency: 15798.3 cm-1 Mirror velocity: 0.3165 Interferogram peak position: 8192 Aperture: 14.00 Apodization: Happ-Genzel Sample gain: 4.0 Phase correction: Power spectrum High pass filter: 200.0000 Number of background scans: 0 Low pass filter: 11000.0000 Background gain: 0.0 COLLECTION ERRORS DATA DESCRIPTION Errors During Sample Collection Number of points: 8091 Number of Rejected Scans: 0 X-axis: Raman shift (cm-1) Error Types: None Y-axis: Raman intensity First X value: 93.9453 DATA PROCESSING HISTORY Last X value: 3994.3313 Collect Raman Raman laser frequency: 9393.6416 Final format: Shifted spectrum Data spacing: 0.482124 Resolution: 1.000 from 93.9453 to 3994.3313 SPECTROMETER DESCRIPTION Laser power at sample 1.701W Spectrometer: Nicolet 6700+NXR FT

241

Figure C.132 Triphenyl phosphate in amyl acetate 4000-400cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

242

Figure C.133 Triphenyl phosphate in amyl acetate 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 243

Triphenyl phosphate in amyl acetate, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. Number of sample scans: 3840 Y-axis: Raman intensity Sample gain: 4.0 Collection length: 18589.24 sec First X value: 93.9453 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3993.8491 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 93.9453 to DATA DESCRIPTION Digitizer bits: 24 3993.8491 Number of points: 8090 Mirror velocity: 0.3165 Laser power at sample 1.705W X-axis: Raman shift (cm-1) Aperture: 14.00

244

Figure C.134 Triphenyl phosphate in diethyl ether 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

245

Figure C.135 Triphenyl phosphate in diethyl ether 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 246

Triphenyl phosphate in diethyl ether taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta- data. Number of sample scans: 256 Y-axis: Raman intensity Sample gain: 4.0 Collection length: 1267.99 sec First X value: 99.7308 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3700.2354 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 99.7308 to DATA DESCRIPTION Digitizer bits: 24 3700.2354 Number of points: 7469 Mirror velocity: 0.3165 Laser power at sample 1.705W X-axis: Raman shift (cm-1) Aperture: 14.00 247

Figure C.136 Triphenyl phosphate in diethyl phthalate 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

248

Figure C.137 Triphenyl phosphate in diethyl phthalate 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

249

Triphenyl phosphate in diethyl phthalate taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta-data Number of sample scans: 3520 Y-axis: Raman intensity Sample gain: 4.0 Collection length: 20195.70 sec First X value: 100.2129 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3701.1997 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 100.2129 to DATA DESCRIPTION Digitizer bits: 24 3701.1997 Number of points: 7470 Mirror velocity: 0.3165 Laser power at sample 1.696W X-axis: Raman shift (cm-1) Aperture: 14.00

250

Figure C.138 Triphenyl phosphate in ethyl acetate 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

251

Figure C.139 Triphenyl phosphate in ethyl acetate 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

252

Triphenyl phosphate in ethyl acetate taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta- data. Number of sample scans: 1024 Y-axis: Raman intensity Sample gain: 1.0 Collection length: 7431.97 sec First X value: 99.7308 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3700.2354 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 99.7308 to DATA DESCRIPTION Digitizer bits: 24 3700.2354 Number of points: 7469 Mirror velocity: 0.3165 Laser power at sample 1.713W X-axis: Raman shift (cm-1) Aperture: 14.00

253

254

Figure C.140 Triphenyl phosphate in 2-propanol 3700-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

255

Figure C.141 Triphenyl phosphate in 2-propanol 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

Triphenyl phosphate in 2-propanol taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta-data. Number of sample scans: 512 Y-axis: Raman intensity Sample gain: 1.0 Collection length: 2492.50 sec First X value: 99.7308 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3700.2354 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 99.7308 to DATA DESCRIPTION Digitizer bits: 24 3700.2354 Number of poitns: 7469 Mirror velocity: 0.3165 Laser power at sample 1.708W X-axis: Raman shift (cm-1) Aperture: 14.00

256

257

Figure C.142 Triphenyl phosphate in toluene 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

Figure C.143 Triphenyl phosphate in toluene 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

258

Triphenyl phosphate in toluene taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta-data.

Number of sample scans: 1024 Y-axis: Raman intensity Sample gain: 1.0 Collection length: 4994.99 sec First X value: 99.7308 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3700.2354 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 99.7308 to DATA DESCRIPTION Digitizer bits: 24 3700.2354 Number of points: 7469 Mirror velocity: 0.3165 Laser power at sample 1.498W X-axis: Raman shift (cm-1) Aperture: 14.00 259

Figure C.144 Triphenyl phosphate in trichloroethylene 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

260

Figure C.145 Triphenyl phosphate in trichloroethylene 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

261

Triphenyl phosphate in trichloroethylene taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta-data. Number of sample scans: 512 Y-axis: Raman intensity Sample gain: 4.0 Collection length: 2569.05 sec First X value: 93.9453 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3994.3313 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 93.9453 to DATA DESCRIPTION Digitizer bits: 24 3994.3313 Number of points: 8091 Mirror velocity: 0.3165 Laser power at sample 1.747W X-axis: Raman shift (cm-1) Aperture: 14.00 262

Figure C.146 Triphenyl phosphate (liquid) 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 263

Figure C.147 Triphenyl phosphate (liquid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

264

Triphenyl phosphate (liquid) taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer, meta-data.

Number of sample scans: 1024 Y-axis: Raman intensity Sample gain: 4.0 Collection length: 4999.41 sec First X value: 93.9453 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3994.3313 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 93.9453 to DATA DESCRIPTION Digitizer bits: 24 3994.3313 Number of points: 8091 Mirror velocity: 0.3165 Laser power at sample 1.705W X-axis: Raman shift (cm-1) Aperture: 14.00

265

Figure C.148 Triphenyl phosphate (solid) 4000-400 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

266

Figure C.149 Triphenyl phosphate (solid) 900-600 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 267

Triphenyl phosphate (solid) taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer meta-data.

Number of sample scans: 2688 Y-axis: Raman intensity Sample gain: 4.0 Collection length: 13896.33 sec First X value: 93.9453 High pass filter: 200.0000 Resolution: 1.000 Last X value: 3993.8491 Low pass filter: 11000.0000 Levels of zero filling: 0 Raman laser frequency: 9393.6416 Number of scan points: 41248 Data spacing: 0.482124 COLLECTION ERRORS Number of FFT points: 65536 Errors During Sample Collection Laser Frequency: 15798.3 cm-1 SPECTROMETER DESCRIPTION Number of Rejected Scans: 0 Interferogram peak position: 8192 Spectrometer: Nicolet 6700+NXR FT Error Types: None Apodization: Happ-Genzel Source: Off Phase correction: Power spectrum Detector: InGaAs DATA PROCESSING HISTORY Number of background scans: 0 Smart Accessory ID: 03 Collect Raman Background gain: 0.0 Beamsplitter: CaF2 Final format: Shifted spectrum Sample spacing: 1.0000 Resolution: 1.000 from 93.9453 to DATA DESCRIPTION Digitizer bits: 24 3993.8491 Number of points: 8090 Mirror velocity: 0.3165 Laser power at sample 1.666W X-axis: Raman shift (cm-1) Aperture: 14.00 268

Chemical Spectra: Analysis of Aircraft Recognition Model Residue

Figure C.150 Top: Diethyl phthalate standard, Middle: Aircraft recognition model residue after ethyl acetate has been evaporated, Bottom: Triphenyl phosphate, taken with Almega XR Dispersive Raman spectrometer, 3500-150 cm-1.

269

Figure C.151 Comparison between Blue: Dimethyl phthalate, Red: Aircraft recognition model residue and Pink: diethyl phthalate, 1250-720cm-1, Taken with Almega XR Dispersive Raman spectrometer.

270

Figure C.152 Identification of all the contribution of the peaks seen in the residue removed from the aircraft recognition models, 3500-150 cm-1 Taken with Almega XR Dispersive Raman spectrometer.

271

Chemical Spectra: Recrystallization of TPP in Solvents

Table C.10: Recrystallization of Triphenyl Phosphate in Various Solvents Solvent Solvent amount in µL TPP (amount in grams) Amyl acetate 200µL 0.1265 Acetone 400µL 0.4474 Acetonitrile 400 µL 1.93 m-xylene 400 µL 0.3502 Tricholorethylene 400 µL (d=1.46g/cm3) 0.03366 Diethyl phthalate 200 µL (d=1.112g/cm3) 0.05713 Acetic acid 200 µL (d=1.049 g/cm3) 0.32549

Solvent Solvent amount in µL TPP (amount in grams) Amyl acetate 200µL 0.1265 Acetone 400µL 0.4474 Acetonitrile 400 µL 1.93 m-xylene 400 µL 0.3502 Tricholorethylene 400 µL (d=1.46g/cm3) 0.03366 Diethyl phthalate 200 µL (d=1.112g/cm3) 0.05713 Acetic acid 200 µL (d=1.049 g/cm3) 0.32549 Hexanes (not 200 µL (d= 0.6548 g/cm3) Did not dissolve listed) 2-propanol (not 400 µL (d=0.786 g/cm3) 0.0658 listed) Toluene (not listed) 396 µL (d=0.8669) .08586

272

Figure C.153 TPP recrystallized in acetone spot 1 (solution) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

273

Figure C.154 TPP recrystallized in acetone spot 1 (solution) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

274

Figure C.155 TPP recrystallized in acetone spot 2 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

275

Figure C.156 TPP recrystallized in acetone spot 2 liquid solidifying 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

276

Figure C.157 TPP recrystallized in acetone spot 3 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

277

Figure C.158 TPP recrystallized in acetone spot 3 (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

278

Figure C.159 TPP recrystallized in acetone spot 4 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

279

Figure C.160 TPP recrystallized in acetone spot 4 (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

280

Figure C.161 TPP recrystallized in acetone spot 5 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a

6700 FTIR spectrometer. 281

Figure C.162 TPP recrystallized in acetone spot 5 (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

282

Figure C.163 TPP recrystallized in acetone spot 6 (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

283

Figure C.164 TPP recrystallized in acetone spot 6 (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

284

Figure C.165 TPP recrystallized in acetonitrile spot 2 (partial crystallization) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

285

Figure C.166 TPP recrystallized in hexanes (solid) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

286

Figure C.167 TPP recrystallized in hexanes (solid) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

287

Figure C.168 TPP recrystallized in 2-propanol spot 1 (solution) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

288

Figure C.169 TPP recrystallized in 2-propanol spot 1 (solution) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

289

Figure C.170 TPP recrystallized in 2-propanol spot 2 (mostly crystallized) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

290

Figure C.171 TPP recrystallized in 2-propanol spot 2 (mostly crystallized) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

291

Figure C.172 TPP recrystallized in 2-propanol spot 3 (mostly crystallized) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

292

Figure C.173 TPP recrystallized in 2-propanol spot 3 (mostly crystallized) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

293

Figure C.174 Comparison of two time points:TPP recrystallized in 2-propanol spot 2 (solution phase) and 3 (mostly crystallized) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

294

Figure C.175 TPP recrystallized in toluene (solution phase) 1300-100 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer.

295

Figure C.176 TPP recrystallized in toluene (solution phase) 750-700 cm-1, taken with NXR FT-Raman module attached to a 6700 FTIR spectrometer. 296

Chemical Spectra: Identifying the bond responsible for a peak between 750-700cm-1

Table D.11: Peaks in various chemicals in the range 900-600cm-1.

TBP TBOEP TEPO TPPO TPP(s) TCP (l) TEP (l) (l) (l) (s) (s) 886 ------893 w -- -- m ------833 s 839 s -- -- 816 -- -- 813 m ------m-s 792 w ------771 773 w ------m-s 727 m- 734 m- 731 m- 722 Occurs only in systems 742 m-s -- -- s s s m with a C-O-P ------685 m 618 m 617 m ------621 s 618 m Names are given in an abbreviated form: TPP-triphenyl phosphate, TCP-tricresyl phosphate, TEP-triethyl phosphate, TBP-tributyl phosphate, TBOEP-tributyoxyethyl phosphate, TEPO- triethylphosphine oxide, and TPPO-triphenylphosphine oxide; with an indication as to their state upon analysis (s)-solid, (l)-liquid. Peaks in wavenumber with an intensity indication: w-weak, m-medium, s-strong, -- no peak

297

Figure C.177 Tributoxyethyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer.

298

Figure C.178 Tributoxyethyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

299

Figure C.179 Tributyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer.

300

Figure C.180 Tributyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

301

Figure C.181 Tricresyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer.

302

Figure C.182 Tricresyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

303

Figure C.183 Triethyl phosphate 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer.

304

Figure C.184 Triethyl phosphate 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

305

Figure C.185 Triethyl phosphite 3500-150 cm-1, taken with Almega XR Dispersive Raman spectrometer.

306

Figure C.186 Triethyl phosphite 900-600 cm-1, taken with Almega XR Dispersive Raman spectrometer.

307

Figure C.187 Triethyl phosphine oxide 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer.

308

Figure C.188 Triethyl phosphine oxide 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer.

309

Figure C.189 Triphenyl phosphate 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer.

310

Figure C.190 Triphenyl phosphate 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer.

311

Figure C.191 Triphenyl phosphite 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer.

312

Figure C.192 Triphenyl phosphite 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer.

313

Figure C.193 Triphenyl phosphine oxide 3500-150 cm-1 taken with Almega XR Dispersive Raman spectrometer.

314

Figure C.194 Triphenyl phosphine oxide 900-600 cm-1 taken with Almega XR Dispersive Raman spectrometer.

315

APPENDIX D. SCANNING ELECTRON MICROSCOPY AND ENERGY DISPERSIVE X-RAY SPECTROSCOPY

Figure D.195 SEM-EDX, Aircraft recognition model fragment, uncoated. Magnification 1900x, HV 10.0kV, working distance 12.8mm. Carbon in green, phosphorus in purple.

Figure D.196 SEM-EDX, Aircraft recognition model fragment, uncoated. Magnification 320x, HV 10.0kV, working distance 11.5mm. Carbon in green, phosphorus in purple.

316

Figure D.197 SEM-EDX Triphenyl phosphate recrystallized in acetonitrile, mounted on carbon sticker, uncoated. Magnification 23x, HV 10.0kV, working distance 11.5mm.

Figure D.198 SEM, Aircraft recognition model fragment after extraction in toluene. Magnification 30x, HV 10kV, working distance 10.5mm. Backscatter electron mode.

Figure D.199 SEM, Aircraft recognition model fragment after toluene extraction. Left left, secondary electron mode. Right EDX image, Silicon-green and phosphorus-purple overlay.

317

Figure D.200 SEM, Magnification 950x, HV 10.0kV, working distance 10.5mm. Right: secondary electron image, Middle: EDX map of phosphorus, Left: EDX map of carbon

318

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