The strain hardening behavior of polymers has important roles in processing such as foaming, film formation, and fiber spinning. The most common method to enhance strain hardening is to introduce a long-chain branching structure on the backbone of a linear polymer, but this method is costly and challenging to tailor the behavior. We hypothesized that in situ shrinking fibers can increase the strain hardening of linear polymers, and the degree can be efficiently controlled. In this study, we show that heat-activated shrinking fibers compounded in linear polypropylene enhance strain hardening and foamability. Moreover, changing processing conditions, such as temperature, can amplify the degree of enhancement. Rheological measurements and physical foaming tests are shown to support our hypothesis.

聚合物的应变硬化行为在诸如发泡，成膜和纤维纺丝的加工中具有重要作用。增强应变硬化的最常用方法是在线性聚合物的骨架上引入长链支化结构，但这种方法成本高昂，并且难以适应行为要求。我们假设原位收缩纤维可以增加线性聚合物的应变硬化，并且可以有效地控制其程度。在这项研究中，我们表明在线性聚丙烯中复合的热活化收缩纤维可增强应变硬化性和发泡性。而且，改变处理条件，例如温度，可以放大增强程度。流变学测量和物理发泡测试表明支持我们的假设。