SELF-REINFORCED PREPREGS, LAMINATES AND INJECTION MOLDINGS OF LCP/LCP BLENDS

Self-reinforced prepregs (sheets) were prepared by stretching sheets made of blends of two LCP's. LCP1 was based on 6-oxy-2-naphthoyl, and p-oxybenzoyl moieties. LCP2 was based on p-oxybenzoyI, terephthaloyl, and hydroquinone moieties. LCP's were blended, at the temperature at which both components were melt processible, by a single-screw extruder followed by a static miser, coat-hanger die and stretching device The prepared prepregs were laid up in multi-layers in the stretching direction and 45 degrees with respect to each previous layer. The lay-ups were compression molded into laminates at a temperature below the melting point of LCP2 but above that of LCP1. The formation of self-reinforcement of one LCP by the other as a function of the processing conditions was studied. The LCP blends in the form of prepregs and pellets of unstretched blends were also injection molded at the barrel temperature below the melting point of LCP2. The theological and thermal properties and the morphology of the blends were investigated. The mechanical properties of prepregs, laminates with controlled anisotropy, and injection molded samples were measured. Structure-processing-property relationships were analyzed, and the differences in behavior of LCP/LCP and LCP/thermoplastics systems were identified.