Creep behavior and mechanical properties of isotactic polypropylene composites via twice melt injection molding

Abstract Nowadays, the improvement of injection molding technology development research is in great demand due to the limitation of convenient injection molding for structural engineering applications. For injection-molded products, oriented structure is ubiquitous. To promote the formation of oriented structure, exert a positive impact on the final mechanical properties of polymer products, an advanced injection molding process is used to achieve multiple shear melt in this work. Based on our previous work about melt multi-injection molding technology, to investigate the influence about oriented structure of composites attracted by higher shear stress, iPP/MWCNTs and iPP/β-NA composites were studied. Compared to traditional injection-molded samples, the addition of MWCNTs impede the formation of oriented structure. For iPP/β-NA composites, the higher flow shear stress inside the mold wall increase the overall crystallinity but restrain the growth of β-crystal.