Clemson University TigerPrints All Dissertations Dissertations 12-2010 PRODUCTION AND CHARACTERIZATION OF ARAMID OPOLC YMER FIBERS FOR USE IN CUT PROTECTION Jeffrey Moreland Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_dissertations Part of the Materials Science and Engineering Commons Recommended Citation Moreland, Jeffrey, "PRODUCTION AND CHARACTERIZATION OF ARAMID COPOLYMER FIBERS FOR USE IN CUT PROTECTION" (2010). All Dissertations. 676. https://tigerprints.clemson.edu/all_dissertations/676 This Dissertation is brought to you for free and open access by the Dissertations at TigerPrints. It has been accepted for inclusion in All Dissertations by an authorized administrator of TigerPrints. For more information, please contact [email protected]. PRODUCTION AND CHARACTERIZATION OF ARAMID COPOLYMER FIBERS FOR USE IN CUT PROTECTION A Dissertation Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Fiber and Polymer Science by Jeffrey C. Moreland December 2010 Accepted by: Dr. Philip Brown, Committee Chair Dr. Gary Lickfield Dr. Marian Kennedy Dr. Julia Sharp ABSTRACT High-performance fibers such as para-aramids are used extensively in gloves for cut protection. However, the inherent cut resistance of these fibers and the relationship between cut resistance and other material properties is not known. To better understand cut resistance at the material level, an experiment was conducted using a lab-scale wet spinning system to produce and characterize aramid copolymer fibers. To facilitate the use of lab-scale equipment, the experiment was conducted as a four- factor split-plot response surface design. The four treatment factors studied were solvent concentration in the coagulation bath, the amount of salt in the coagulation bath, the degree of stretching during coagulation, and the degree of stretching after coagulation. The cut resistance of the fibers was measured using a new cut testing device developed specifically for testing single-end yarns. Other physical properties as well as the morphology of the fibers were also investigated. The cut strength of the fibers was improved by stretching after coagulation but was influenced more by the conditions of coagulation. In this experiment the optimum conditions for maximizing cut resistance occurred at slow rates of coagulation with high concentrations of solvent and salt in the bath. The resulting fibers were nearly isotropic in mechanical performance and had a coarse granular morphology that transitioned into domains of macrofibrils inside the fibers after stretching. As the coagulation rate slowed, the cross-section of the fibers became increasingly round, which also improved the cut resistance of the fibers. The tensile properties of the fibers were not significantly affected by the coagulation conditions but were improved by increasing molecular orientation as a ii result of stretching after coagulation. The degree of molecular orientation in the experimental fibers was relatively low, which resulted in lower tensile strength but improved transverse properties over commercial aramid fibers. Despite having low tensile strength, the cut strength of the experimental aramid copolymer fibers is predicted to exceed that of commercial aramid fibers under optimized processing conditions. iii DEDICATION To my wife and daughter. iv ACKNOWLEDGMENTS This work was made possible through financial support provided by Ansell Healthcare Products, LLC under the continued guidance and encouragement of Dr. Michael Zedalis and Dr. Cherilyn Nelson. Additional support was provided by the Clemson University Research Foundation and the Center for Advanced Engineering Fibers and Films at Clemson University. The author would also like to acknowledge the work of Joel Barden and Jessica Domino for their assistance with this research. Portions of this work have been reprinted from the published article “Lab-Scale Fiber Spinning Experimental Design Cost Comparison” by Moreland, Sharp, and Brown (Journal of Engineered Fiber and Fabrics, Volume 5, Issue 1, 2010, p. 39-49) with permission from INDA. v TABLE OF CONTENTS Page TITLE PAGE ............................................................................................................... i ABSTRACT ................................................................................................................ ii DEDICATION ........................................................................................................... iii ACKNOWLEDGMENTS .......................................................................................... iv LIST OF TABLES ................................................................................................... viii LIST OF FIGURES ..................................................................................................... x CHAPTER I. INTRODUCTION ..................................................................................... 1 1.1 Product and Material Properties Related to Cut Protection .............. 2 1.2 Classification and Formation of Aramid Fibers ..............................15 1.3 Structure Development and Orientation in Wet Spinning ...............20 1.4 Aramid Fiber Structure and Properties ...........................................24 1.5 Experimental Design for Fiber Spinning Systems ..........................27 1.6 Research Objectives ......................................................................31 II. EXPERIMENTAL ....................................................................................32 2.1 Polymer Solution Preparation ........................................................32 2.2 Wet-Spinning Experimental Design ...............................................34 2.3 Experimental Design Cost Comparison..........................................40 2.4 Development of a Cut Resistance Tester for Fibers and Yarns .......44 2.5 Single-End Yarn Testing Methods .................................................55 2.6 Single-Fiber Torsion Testing .........................................................62 2.7 Morphological Characterization .....................................................63 III. RESULTS AND DISCUSSION ................................................................67 3.1 Experimental Design Cost Comparison..........................................67 3.2 Cut Testing Device Comparison ....................................................88 3.3 Wet-Spinning Experimental Design Results ..................................91 3.4 Effects of Heat Treatment ............................................................ 148 vi Table of Contents (Continued) Page 3.5 Comparison to Commercial Fibers............................................... 149 IV. CONCLUSIONS AND RECOMMENDATIONS ................................... 151 4.1 Benefits of Lab-Scale Experimental Design ................................. 151 4.2 Cut Resistance Testing of Yarns .................................................. 152 4.3 Effects of Coagulation Conditions on Fiber Morphology ............. 152 4.4 Effect of Processing Conditions on Longitudinal Fiber Properties .............................................................................. 154 4.5 Effect of Processing Conditions on Transverse Fiber Properties .............................................................................. 154 4.6 Fiber Cut Strength ....................................................................... 155 4.7 Recommendations for Future Work ............................................. 156 APPENDICES ......................................................................................................... 158 A: CRT Program Python Module ................................................................. 159 B: SAS Programming .................................................................................. 174 C: Python Graphing Procedures ................................................................... 188 REFERENCES......................................................................................................... 207 vii LIST OF TABLES Table Page 1-1 Typical spinning conditions for isotropic aramid solutions [69-72]. ...........20 1-2 Physical properties of commercial aramid fibers. ......................................27 2-1 Coded and uncoded levels of the treatment factors for the response surface design......................................................................................36 2-2 Experimental runs for the split-plot response surface design. .....................36 2-3 Processing parameters required to calculate the cost of a fiber spinning experiment. .........................................................................................40 3-1 The processing parameters of the spin line used in the experiment. ...........68 3-2 Coded and uncoded levels of each factor for Design I. ..............................69 3-3 Coded factor levels, resets, cost parameters, and responses for each run of Design I*. .......................................................................................70 3-4 ANOVA table for Design I........................................................................73 3-5 Model parameter estimates for the treatments effects of Design I. .............74 3-6 Coded and uncoded factor levels for Design II. .........................................76 3-7 Coded factor levels, resets, cost parameters, and