Eastern Illinois University The Keep Masters Theses Student Theses & Publications 2000 Effect of Antioxidants on Ultra High Molecular Weight Polyethylene (UHMWPE) Clifford Schrader Eastern Illinois University This research is a product of the graduate program inTechnologyat Eastern Illinois University.Find out more about the program. Recommended Citation Schrader, Clifford, "Effect of Antioxidants on Ultra High Molecular Weight Polyethylene (UHMWPE)" (2000).Masters Theses. 1640. https://thekeep.eiu.edu/theses/1640 This is brought to you for free and open access by the Student Theses & Publications at The Keep. It has been accepted for inclusion in Masters Theses by an authorized administrator of The Keep. For more information, please [email protected]. EFFECT OF ANTIOXIDANTS ON ULTRA IDGH MOLECULAR WEIGHT POLYETHYLENE (UHMWPE) (TITLE) BY Clifford Schrader THESIS SUBMITIED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Science in Technology IN THE GRADUATE SCHOOL, EASTERN ILLINOIS UNIVERSITY CHARLESTON, ILLINOIS 2000 YEAR I HEREBY RECOMMEND THAT THIS THESIS BE ACCEPTED AS FULFILLING THIS PART OF THE GRADUATE DEGREE CITED ABOVE 1-:z.t-- 00 DATE 7/ , _ :r'-1 I' ·-l.- ,r_, DATE THESIS COMMITTEE MEMBERS Ping Liu, Ph.D., P.E., C.Q.E., and C.S.I.T. Date Professor Thesis Director Graduate Coordinator School of Technology 9-Js ·-t- o Larry D. Helsel, D.Ed. Date Professor School of Technology Lj . 2 -;- •-'?/ Louis Butler, Ph.D. Date Professor Tech Ed Coordinator School of Technology Abstract: This thesis presents a study on the effects of antioxidants on the oxidative induction time (OIT), thermal behavior, and hardness property of ultra high molecular weight polyethylene (UHMWPE). The antioxidants were dissolved into methanol alcohol before the solution was mixed with UHMWPE powder. The mixture was degassed under vacuum, and then compression-molded into disks 1.25 in. in diameter. Different antioxidants were evaluated at concentrations up to 0.6 percent. A 0.6 percent concentration was used to screen the effectiveness of various antioxidants. Effect of antioxidant concentration was investigated in the range between 0 and 0.6 percent. OIT was evaluated on UHMWPE with various antioxidants to understand the effects of antioxidants on oxidation resistance of the polymer. The experiments were performed using high pressure differential scanning calorimetry (HP DSC) with an isothermal temperature of 165 °C, and pure dry oxygen under a pressure of 500 psi. Regular differential scanning calorimetry (DSC) was used to evaluate the thermal behavior and changes in molecular structure of the polymer with antioxidants, in which a scanning rate of 10 °C/min. was utilized from room temperature to 200 °C. With the regular DSC, thermal stability ofUHMWPE with various antioxidants was assessed from room temperature up to 300 °C. Durometer hardness (Type D) was tested on the polymer in order to understand changes in mechanical property and polymeric structure of UHMWPE due to antioxidants. P The OIT of UHMWPE was increased with the addition of antioxidants except carotene. Quercetin, at a concentration of 0.6 percent, was the most effective antioxidant, which increased the OIT 1133 percent. The effectiveness of antioxidant increased as ii their concentrations increased in the tested range. The effectiveness can be arranged in descending order as: quercetin > BNX 1010 > GSPE > BHT >vitamin E > TBHQ > vitamin C > f3-carotene. There was a weak synergy between BHT and vitamin E. A strong synergy was demonstrated between GSPE and quercetin. Results indicated that the addition of antioxidants had very little or no effect on the thermal behavior ofUHMWPE. This fact suggests antioxidants at the concentrations studied had little effect on the molecular structure of UHMWPE. Thermal stability of UHMWPE was increased with the addition of antioxidants. The effectiveness of the antioxidants on thermal stability in descending order was: quercetin > BNX 1010 >vitamin E > GSPE > BHT > TBHQ >vitamin C. Hardness test results determined that the addition of antioxidants did not significantly change or increase the hardness of UHMWPE, which indicates no significant cross-linking of the polymer. iii Acknowledgement I would like to give my sincerest thanks to Dr. Ping Liu for the opportunity to conduct this research and for his inspiration, guidance, and wisdom throughout the research and thesis writing process. I would also like to thank Dr. Louis Butler and Dr. Larry Helsel for their advisement and encouragement during the thesis writing process. I would also like to acknowledge a few of my fellow graduate students, Brett Anderson, Chris Lauret, and Russel Reinhart, who have given me help, encouragement, and made graduate school a unique experience. Favorable mention is given to Biomet Inc., Marzo Inc., IntraHealth Nutraceuticals, and Eastman Chemical Products for supplying materials used in this research. I would also like to thank my parents and family for their support and encouragement. iv Table of Contents Page 1. INTRODUCTION ......................... ,.................................... 1 1.1 Statement of Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3 1.2 Significance of Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3 1.3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.4 Assumptions .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5 1.5 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.6 Delimitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 1.7 Hypothesis .................................................................... 7 2. REVIEW OF LITERATURE ................................................ 8 2.1 Significance of Joint Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.2 Problems Associated with Joint Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.3 Vitamin E and UIIMWPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10 2.4 Natural and Synthetic Antioxidants ................._ . ...................... 10 2.5 Thermal Analysis ............................................................. 14 2.6 Method of Evaluation for Oxidation Resistance ......................... 15 2.7 Method of Hardness Evaluation .......................................· ... .. 16 3. METHODOLOGY OF THE RESEARCH ....................................... 18 3. 1 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3 .2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 v 3.3 Thermal Behavior Evaluation Using Differential Scanning Calorimetry (DSC) ........................................................... 21 3.4 Thermal Stability Evaluation Using Differential Scanning Calorimetry (DSC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 22 3.5 Oxidative Induction Time (Oin Evaluation ............................. 22 3 .6 Durometer Hardness Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 4. PRESENTATION AND INTERPRETATION OF DATA .............. 25 4.1 Effects of Various Antioxidants on Ultra High Molecular Weight Polyethylene (lJHMWPE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.2 Effects of Various Antioxidants on Durometer Hardness of UHMWPE ..................................................................... 28 4.3 Effects of Various Antioxidants on the Thermal Behavior of UHMWPE ..................................................................... 30 4.4 Effect of Antioxidant Concentration on OIT ofUHMWPE ............ 34 4.5 Effects of Antioxidant Concentration on Hardness ofUHMWPE ..... 38 4.6 Effects of Antioxidant Concentrations on the Thermal Behavior ofUHMWPE .................................................................. 39 4.7 Testing for Synergy Between Antioxidants ............................... 41 4.8 Effects of Antioxidant Combinations on Hardness ...................... ·43 4.9 Effects of Antioxidant Combinations on the Thermal Behavior of UHMWPE .................................................................. 44 vi 5. CONCLUSION ................................................................... 46 RECOMMENDATION FOR FURTHER RESEARCH .................. 47 REFERENCES ................................................................... 48 vii List of Tables Table Page 1 Physical Properties of Antioxidant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2 Oxidative Induction Time (OIT) of Ultra High Molecular Weight Polyethylene (UHMWPE) with 0.6 Percent Antioxidant . . . . . . . . . . . . . . . . . . .. 28 3 Average Durometer Hardness at 1 Second ..................................... 29 4 Differential Scanning Calorimeter (DSC) Results of UHMWPE with 0.6 Percent Antioxidant ........................................................... 32 5 Oxidation Temperatures ofUHMWPE with 0.6 Percent Antioxidant ...... 34 6 OIT ofUHMWPE with 0.1, 0.2, 0.4, and 0.6 Percent Antioxidants (OIT [min]/Net Percent) .......................................................... 35 7 Average Durometer Hardness at 1 Second as a Function of Antioxidant Concentrations ...................................................... 38 8 Differential Scanning Calorimeter (DSC) Results ............................. 40 9 OIT ofUHMWPE with Combinations and Individual Antioxidants at 0.2 Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 42 10 Average Durometer Hardness at 1 Second of Samples with Antioxidant Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 11 Differential Scanning Calorimeter (DSC) Results ofUHMWPE with Combinations of Antioxidants .............................................. 45