Effect of Cold-Drawn Fibers on the Self-Reinforcement of PP/LDPE Composites

In our previous study, a method to fabricate super-ductile polypropylene/low-density polyethylene (PP/LDPE) blends was proposed, and a fiber-shape structure was shown to be formed, presenting necking propagation during tensile testing. In this study, the mechanical properties and thermal behavior of the necking region of tested super-ductile PP/LDPE samples were carefully investigated and further compared with the melt-stretched, untested, and thermo-mechanical-history-removed samples by differential scanning calorimetry and tensile testing. The results suggest that the tested samples have high mechanical properties and are more thermo-mechanically stable than the common PP/LDPE blends and melt-stretched samples. Additionally, to investigate their structure-property relationship, the necking region of the tested samples was further characterized by scanning electron microscopy and hot-stage polarized light microscopy. It can be concluded that the variation of the microstructure can be attributed to the cold-drawn fibers (CDFs), which were more stable thermally, formed during the tensile test. Furthermore, the CDFs were used for the filler in PP/LDPE blends. The experimental results of the different PP/LDPE composites indicate that the CDFs are a good reinforcement candidate and have the ability to improve the mechanical properties of the PP/LDPE blends.