Polyethylene terephthalate composite and foam with superior mechanical properties from the synergistic simultaneous in situ fibrillation of liquid crystal polymer and polytetrafluoroethylene.

Liquid crystal polymers (LCP) and polytetrafluoroethylene (PTFE) were in situ fibrillated to produce polyethylene terephthalate (PET)/LCP/PTFE composites using a simple and scalable extrusion drawing techniques. The PET/LCP/PTFE composites included high-aspect-ratio PTFE fibrils and rod-like LCP fibrils. The simultaneous in situ fibrillation of LCP and PTFE exerted synergistic effects on crystalline behaviour and viscosity of PET, especially for mechanical properties of PET and its foam. The tensile strength of PET/LCP/PTFE composites and impact strength representing improvements of 34% and 62% over those of PET. The improved mechanical properties can be attributed to the simultaneous abundance of orienting rod-like rigid LCP fibrils and tangling flexible PTFE fibrils in the PET matrix, which contributed to stress transfer from matrix to fibrils. A simultaneously in situ fibrillated PET/LCP/PTFE composite foam was fabricated using a batch foaming system with supercritical CO2 as blowing agent. The cell diameter of this foam decreased by 23% over that of standard PET foam, while its cell density increased twofold. The smaller cell diameter of PET/LCP/PTFE foam and superior mechanical properties of PET matrix collectively led to the good mechanical properties of PET/LCP/PTFE foam. Specifically, the compressive strength of the PET/LCP/PTFE foam represents a 35% increase over that of PET foam. [ABSTRACT FROM AUTHOR]