Crystallization and compatibilization of polypropylene-liquid crystalline polyester blends

A liquid crystalline polyester, LC3000, has been blended with polypropylene. These polymers form an incompatible and immiscible blend. Polypropylene grafted with epoxy via glycidyl methacrylate forms an effective compatibilizer. The dispersed liquid crystalline polyester particle size was decreased when the compatibilizer was used. The polyester influenced the morphology of the polypropylene continuous phase by increasing the nucleation, and the effect was enhanced when the compatibilizer was present. This was demonstrated using continuous cooling DSC where the crystallization temperatures were increased. Isothermal crystallization showed decreased crystallization half-times with the polyester present, and these were further reduced with compatibilizer. Avrami analysis showed that the exponent values increased by an average of 0.1-0.2, so nucleation was assisted by the LC3000, and the rate coefficients were increased. The continuous cooling and isothermal DSC measurements provided complementary results. Optical microscopy showed that the spherulite size of the polypropylene was reduced. (C) 2000 John Wiley & Sons, Inc.