In-Situ Formation of Reinforced Thermoplastic Composites

Abstract

A process has been developed in our laboratories in which the reinforce ment of engineering thermoplastics is generated during melt processing. The process con sists of blending thermotropic liquid crystalline polymers with engineering thermoplastics in an extruder. On extruding these blends through a sheet die, films (or sheet) are formed in which the LCP phase exists in the form of thin fibrils. The formation of fibrils depends on the presence of certain hydrodynamic conditions defined by the viscosity ratio, capil lary number, and flow type. The sheets are then drawn to impart molecular orientation in the LCP phase. Polyphenylene sulfide (PPS) sheets reinforced with several different LCP's have been formed in which the properties are significantly enhanced. The modulus of these sheets represented almost a fourfold increase over that of the pure PPS sheet. The dynamic torsional properties of the sheet are also determined using a Rheometrics Mechanical Spectrometer and results are correlated with the structure and molecular ori entation.