The macroscopic mechanical behavior of high-density polyethylene (HDPE) during photodegradation is characterized by decreases of tensile elongation-at-failure. An apparent linear relation between the elongation-at-failure and the molar mass indicates that the decrease of the elongation of HDPE over time is highly dependent on the decrease of the average molar mass. Possible preferential scission of the high molar mass chains was observed for HDPE exposed to ultraviolet (UV) irradiance higher than 40% (61 W/m²) of the full intensity at 50 °C. Tensile modulus of HDPE exposed at 50 °C increased with the exposure time until reaching the complete loss of ductility except the 5% UV. For 40% UV/30 °C as well as for 5% UV/50 °C, the young modulus trend cannot be evaluated with performed (small) duration. Nanomechanical test results suggest that the increased tensile modulus is due to stiffening of the entire cross-section. Furthermore, HDPE showing the complete loss of ductility exhibited significantly higher modulus in the surface regions than the core regions particularly for the UV intensity higher than 40% (61 W/m²), which increased crack sensitivity to cause embrittlement of the entire specimens.

高密度聚乙烯 (HDPE) 在光降解过程中的宏观力学行为以断裂拉伸伸长率降低为特征。断裂伸长率与摩尔质量之间明显的线性关系表明，HDPE 伸长率随时间的下降高度依赖于平均摩尔质量的下降。对于暴露于高于 40% (61 W/m ²) 在 50 °C 时的全强度。暴露在 50 °C 下的 HDPE 的拉伸模量随着暴露时间的增加而增加，直到达到完全失去延展性（5% 紫外线除外）。对于 40% UV/30 °C 以及 5% UV/50 °C，年轻模量趋势无法通过执行（小）持续时间进行评估。纳米力学测试结果表明，拉伸模量的增加是由于整个横截面的硬化。此外，显示完全丧失延展性的 HDPE 在表面区域表现出比核心区域显着更高的模量，特别是当 UV 强度高于 40% (61 W/m ² ) 时，这增加了裂纹敏感性，导致整个样本脆化。