Lin Panpan, Cheng Shiwang, Wang Shi-Qing
Maurice Morton Institute of Polymer Science and Engineering, University of Akron, Akron, Ohio 44325-3909, United States.
ACS Macro Lett. 2014 Aug 19;3(8):784-787. doi: 10.1021/mz5004129. Epub 2014 Jul 24.
The origin of high mechanical stresses in large deformation of polymer glasses has been elusive because both plasticity and elasticity take place. In this work on the nature of the mechanical responses, we carry out uniaxial compression experiments to make simultaneous mechanical and thermal measurements of polycarbonate. Our results confirm that two factors contribute to the growing mechanical stress in the post-yield regime, which is known as "strain hardening". Besides plastic deformation that is intersegmental in origin, chain tension as an intrasegmental component contributes considerably to the measured stress in post-yield. Such a conclusion modifies the previous consensus regarding the nature of strain hardening in mechanical deformation of polymer glasses.
在聚合物玻璃的大变形中，高机械应力的起源一直难以捉摸，因为塑性和弹性都会发生。在这项关于机械响应本质的研究中，我们进行了单轴压缩实验，以同时对聚碳酸酯进行力学和热学测量。我们的结果证实，有两个因素导致了屈服后阶段不断增加的机械应力，即所谓的“应变硬化”。除了源于链段间的塑性变形外，作为链段内成分的链张力对屈服后测量到的应力有很大贡献。这一结论修正了此前关于聚合物玻璃机械变形中应变硬化本质的共识。
