The massive formation of hybrid shish-kebab structures in HDPE/PA6 microfibril blend subjected to melt second flow

摘要

During the melt second flow process, the synergetic effect of intense shear and polyamide 6 (PA6) microfibrils finally results in the massive formation of highly oriented crystalline structures in the entire thickness of high-density polyethylene (HDPE)/PA6 microfibril blend. Interestingly, not only does the small microfibril induce HDPE crystallization to form typical hybrid shish-kebab structure, but the large microfibril (about 2 m in diameter) also induces the formation of local hybrid shish-kebab structure. For the small PA6 microfibril, the oriented HDPE chains caused by the intense shear are absorbed on the whole surface of the microfibril and then a complete polymer underlayer is formed. Subsequently, the crystal nuclei appear on the underlayer, and then the other oriented HDPE chains overgrow from the nuclei in the form of folded chains and grow perpendicular to the microfibril. Finally, the typical hybrid shish-kebab structure is formed. While for the large PA6 microfibril, a few HDPE chains can be still absorbed on the microfibril surface due to the high surface energy of PA6. However, the driving force is insufficient to absorb largely oriented HDPE chains to form complete hybrid shish but only local adsorption layer, so the local hybrid structure is formed. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45274.