Lewis G, Rogers C, Trieu H H
Department of Mechanical Engineering, The University of Memphis, Tennessee, USA.
J Biomed Mater Res. 1998 Fall;43(3):249-60. doi: 10.1002/(sici)1097-4636(199823)43:3<249::aid-jbm5>3.0.co;2-n.
A dynamic thermomechanical analysis method was used to determine the values of the viscoelastic parameters, storage modulus (E') and the tangent of the loss angle (tan delta) of samples taken from the near surface and core regions of ultrahigh molecular weight polyethylene (UHMWPE) bar stock specimens that had been aged in ambient laboratory air for 12 months (the control group) and UHMWPE tibial inserts that had been subjected to the following treatments: gamma sterilization followed by shelf aging in ambient laboratory air for between 56 and 112 months or ethylene oxide (EtO) gas sterilization followed by shelf aging in ambient laboratory air for 73 months. Differential scanning calorimetry was used to determine the melt temperature and percentage crystallinity (%C) of these samples. There were three main findings. First, EtO sterilization produced no statistically significant effect on the values of E' or tan delta (relative to those for the control group), but the values of these parameters were markedly affected by gamma sterilization. Second, for gamma-irradiated samples, E' increased with an increase in the shelf aging time. Third, there was a strong direct association between E' and % C. The various potential uses of this association are described, paying special attention to its likely role in predicting the in vivo wear of UHMWPE tibial inserts.
采用动态热机械分析方法，测定了在实验室环境空气中老化12个月的超高分子量聚乙烯（UHMWPE）棒材试件近表面和芯部区域取样的样品以及经过以下处理的UHMWPE胫骨插入物的粘弹性参数、储能模量（E'）和损耗角正切（tanδ）的值：γ射线灭菌，随后在实验室环境空气中货架老化56至112个月；或环氧乙烷（EtO）气体灭菌，随后在实验室环境空气中货架老化73个月。采用差示扫描量热法测定这些样品的熔融温度和结晶度百分比（%C）。有三个主要发现。第一，EtO灭菌对E'或tanδ的值没有统计学上的显著影响（相对于对照组），但这些参数的值受到γ射线灭菌的显著影响。第二，对于γ射线辐照的样品，E'随货架老化时间的增加而增加。第三，E'与%C之间存在很强的直接关联。描述了这种关联的各种潜在用途，特别关注其在预测UHMWPE胫骨插入物体内磨损方面可能发挥的作用。
