Durham E-Theses The Inuence of Chemical Structure of Model Epoxy Networks on Chemical Resistance DIDSBURY, MATTHEW,PAUL How to cite: DIDSBURY, MATTHEW,PAUL (2014) The Inuence of Chemical Structure of Model Epoxy Networks on Chemical Resistance, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/11009/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk 2 Department of Chemistry The Influence of Chemical Structure of Model Epoxy Networks on Chemical Resistance Matthew Paul Didsbury A thesis submitted for the degree of Doctor of Philosophy 2014 Declaration The work described in this thesis was carried out in the Department of Chemistry at the University of Durham between October 2010 and December 2013. All of the work is my own, except where specifically stated otherwise. No part has previously been submitted for a degree at this or any other university. Statement of Copyright The copyright of this thesis rests with the author. No quotation from it should be published without prior written consent and information derived from it should be acknowledged. i Abstract Structural differences in cross-linked epoxy networks from the use of different isomers (ortho-, meta- and para-) of disubstituted aromatic diglycidyl ethers can have a dramatic effect on the polymer properties. By changing the disubstitution from meta- to para- it has been shown that there is a direct correlation between the diffusion of gasses and the symmetry of related polymers. The aim of this work is to investigate the influence of the chemical structure of aromatic diglycidyl ethers on the ability of the resulting amine-cured epoxy polymer networks to adsorb organic solvents. Pure diglycidyl ethers based on hydroquinone and catechol, have been synthesised in high purity and good yields using a process previously developed at Durham University which utilise elemental fluorine to produce hypofluorous acid. The diglycidyl ether of resorcinol is commercially available and readily purified via vacuum distillation. Using the pure epoxides model networks have been produced by reacting the diglycidyl ethers with the diamine 4,4’-methylenebis(cyclohexylamine) to produce highly cross-linked films. Analytical techniques including DSC, DMTA, TGA, FTIR, solid state NMR, thermodynamic testing, PALs and density measurements have been used to investigate the influence of polymer structure on the network properties. With these materials we are determining the effect of the different epoxide isomers on the chemical resistance of the polymers. The results obtained for the polymers shows consistency with those suggested by the literature which is that the meta- polymer has the best chemical resistance with the other isomers having similar results. ii Acknowledgements I would like to acknowledge several people and groups for their assistance and help throughout my Ph.D and have helped make the thesis possible. I would first like to thank my supervisors Professor Neil R. Cameron and Professor Graham Sandford, for their guidance and advice throughout my Ph.D. I would like to thank the NRC group and the GS group for their help and ideas from group meetings and for the friendly atmosphere created in the lab. I would like to give special thanks to Chris McPake for his training and assistance with using the fluorine rig. I would like to Dan, Sarah, Lauren, Scott, David, Ross, Mike, Adam, Artur, Caitlin, Ffion, Tony, Rob and the rest of office 235 and the tough rugby team for their friendship throughout my period in Durham and for not leaving me to prop the bar up on my own. I would also like to thank all of the technical staff for their help in running analysis with special mention to Dr Allen Kenwright for assistance with solution state NMR. Dr David Apperley and Dr Eric Hughes for their assistance with solid state NMR spectroscopy, Dr Jackie Mosley for her assistance with mass spectrometry, Dr Richard Thompson and Doug Carswell for their help with thermal analysis, Neil Holmes and the lads in the mechanical workshop and the guys down in stores for their help and assistance. Acknowledgements paid also to my industrial supervisors Dr. Colin Cameron and Dr. Anthony Wright from International Paint Ltd, AkzoNobel. Finally I would like to thank all of the people that I have had the pleasure in meeting in and around Durham University that have made my time in Durham enjoyable. I would like to give special thanks to my family who have helped and supported me throughout my life and have pushed to me achieve more than I iii thought possible. Without them none of this would have been possible so I thank them for their love and care by dedicating this thesis to them. iv Glossary of Terms P Permeability coefficient D Diffusion coefficient S Sorption equilibrium J Diffusion flux c Concentration x Distance Mi Initial mass of the polymer Mt Mass of the swollen polymer as a certain time M∞ Mass of the swollen polymer at equilibrium k Constant t Time n Exponent of determining the diffusion mechanism Q(t) Percentage weight gain of solvent at equilibrium h Initial sample thickness Ø Initial slope of linear section of a plot of Q(t) versus t1/2 A Constant for determining the Permachor factor s Constant for determining the Permachor factor Pf Permachor factor Mc Molecular weight between cross-links ϑe Cross-link density A Fitting constant for equation 1.10 B Fitting constant for equation 1.10 C Fitting constant for equation 1.10 Log P Hydrophobicity of a polymer Tg Glass transition temperature EEW Epoxide equivalent weight Mw Molecular weight E’ Storage modulus E’’ Loss modulus tan δ Tan delta v R Gas constant T Temperature Ρ Density Cp Heat capacity co Segment mobility of uncross-linked polymer c∞ Segment mobility of cross-linked polymer ε Lattice energy Ms Mass of solvent uptake AHEW Active hydrogen equivalent weight vi Table of contents Declaration ................................................................................................................. i Statement of Copyright ............................................................................................. i Acknowledgements ................................................................................................. iii Glossary of Terms .................................................................................................... v Table of contents.................................................................................................... vii Chapter 1 – Introduction .......................................................................................... 1 1.1 – Chemical Resistance ..................................................................................... 2 1.2 – Factors Affecting Chemical Resistance.......................................................... 6 1.2.1 – Effects of polymer structure ..................................................................... 6 1.2.2 – Polymer molecular structure .................................................................... 7 1.2.3 – Cross-linking .......................................................................................... 10 1.2.4 – Free Volume .......................................................................................... 15 1.3 – Polymeric Materials used to Achieve Chemical Resistance ......................... 18 1.3.1 – High Performance Polymers .................................................................. 18 1.3.2 – Fluorinated Polymers ............................................................................. 19 1.3.3 – Additives ................................................................................................ 20 1.3.4 – Composites ............................................................................................ 20 1.3.5 – Epoxides ................................................................................................ 21 1.4 – Conventional Synthesis of Epoxides ............................................................ 26 1.4.1 – Via Halohydrin Intermediates ................................................................. 26 1.4.2 – Prilezhaev Reaction ............................................................................... 28 1.5 – Epoxidation using HOF.MeCN ..................................................................... 30 1.5.1 – a brief history of fluorine......................................................................... 30 1.5.2 – Epoxidation using HOF.MeCN ............................................................... 31 vii 1.5.3 – Concluding Remarks ............................................................................. 34 Chapter 2 – Conventional synthesis of diglycidyl ethers ................................... 35 2.1 – Aims and approach .....................................................................................