Through molecular dynamics simulations, we investigated the effects of temperature on the axial tensile behavior of ultra-high molecular weight polyethylene (UHMWPE) crystals, considering the combined effects of transverse compression, strain rate, and molecular weight. The effects of temperature over the range of 100 K to 450 K is shown to reduce the mechanical properties. Existing chain end defects facilitate chain sliding and induce stress concentration in adjacent molecules, thereby reducing the strength and modulus of crystals. Lower molecular weight and higher temperatures promote chain sliding, while higher transverse compression and increased strain rates inhibit chain sliding, resulting in higher properties. Additionally, higher temperatures increase stress concentration due to thermal vibrations, which induce localized high stress conditions within polyethylene chains. The transition of the failure mode from chain sliding to bond breakage occurs at strain rates between 1012 s−1 and 1013 s−1, and is found to be independent of temperature, pressure, and molecular weight. The results are compared to the response of crystals without chain end defects. These insights contribute to a deeper understanding of the behavior of UHMWPE crystals under extreme loading conditions.

中文翻译：

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不同载荷条件下结晶超高分子量聚乙烯轴向拉伸响应的分子动力学研究


通过分子动力学模拟，我们考虑了横向压缩、应变率和分子量的综合影响，研究了温度对超高分子量聚乙烯（UHMWPE）晶体轴向拉伸行为的影响。 100 K 至 450 K 范围内的温度影响会降低机械性能。现有的链端缺陷有利于链滑动并引起相邻分子的应力集中，从而降低晶体的强度和模量。较低的分子量和较高的温度促进链滑动，而较高的横向压缩和增加的应变率抑制链滑动，从而产生更高的性能。此外，较高的温度会因热振动而增加应力集中，从而在聚乙烯链内引起局部高应力条件。失效模式从链滑动到键断裂的转变发生在 1012 s−1 和 1013 s−1 之间的应变速率下，并且发现与温度、压力和分子量无关。将结果与没有链端缺陷的晶体的响应进行比较。这些见解有助于更深入地了解 UHMWPE 晶体在极端负载条件下的行为。