In-Situ Bubble Stretching Assisted Melt Extrusion for the Preparation of HDPE/UHMWPE/CF Composites.

In this work, a novel melt extrusion method under synergy of extensional deformation and in-situ bubble stretching (ISBS) and corresponding apparatus were reported. The structure and working principle were introduced in detail. Polymer composites composed of high density polyethylene (HDPE)/ultrahigh molecular weight polyethylene (UHMWPE)/carbon fiber (CF) were prepared by using this new method. Effects of CF and Azodicarbonamide (AC) contents on composites' morphology, rheological, thermal, and mechanical properties were experimentally investigated. SEM results showed that the CFs dispersed evenly in the matrix when the AC content was relatively high. DSC results showed that co-crystallization of HDPE and UHMWPE occurred in the composites, and the Xc of the composites decreased with the addition of AC or under high CF loadings. TGA results showed that the thermostability of the composites increased markedly with increasing CF loading. Mechanical properties showed that tensile strength increased by 30% with 9 wt % CF and 0.6 wt % AC added. The results aforementioned indicate that the novel melt extrusion method is a green and effective way to prepare HDPE/UHMWPE/CF composites.