Compatibilization of Polymer Blends

点击翻译按钮获取中文摘要

New "engineered" thermoplastics are polymer-polymer blends which have a high modulus, good toughness, and high softening temperatures. They can therefore be used in designed structures which typically require metals. Other polymer blends have special properties that permit them to be used for particular applications. Most blends are made by mixing two or more immiscible polymers in the molten state. Their multiphase structure must be stabilized to prevent coalescence when the blend is extruded or molded by a polymer processor. The main method for compatibilization is to use a block copolymer which can act like a polymeric soap to stabilize the morphology. This block copolymer can be premade and compounded into the mixture or it can be formed in situ by coupling reactions between the two different chains. A research program is planned to understand and control the morphology which develops during melt mixing. Two model pairs of immiscible polymers, polystyrene (PS) and poly(2- vinylpyridine) PVP, and linear low density polyethylene (LLPE) and poly(ethylene-co-polypropylene) PEP will be used as test materials. The LLDPE/PEP system offers unique opportunities since it can be made miscible at elevated temperatures. Morphologies created by precipitation from the miscible melts will be compared by mixing immiscible melts and by reactive coupling. New and useful morphologies should result from this research as well as strategies and quantitative models for efficient compatibilization of polymer blends.