Compatibilization of Polymer Blends

新型的“工程”热塑性塑料是具有高模数、良好韧性和高软化温度的聚合物-聚合物共混物。因此，它们可以用于通常需要金属的设计结构中。其他聚合物共混物具有特殊的性质，允许它们用于特定的应用。大多数混合物是由两种或两种以上不相容的聚合物在熔融状态下混合而成的。当共混物被聚合物加工机挤出或模塑时，它们的多相结构必须稳定，以防止聚合。增容的主要方法是使用嵌段共聚物来稳定形态，这种嵌段共聚物可以起到聚合肥皂的作用。这种嵌段共聚物可以预制并复合成混合物，也可以通过两个不同链之间的偶联反应原位形成。计划进行一项研究计划，以了解和控制熔体混合过程中形成的形态。两种不相容聚合物的模型对，聚苯乙烯(PS)和聚(2-乙烯基吡啶)PVP，并以线型低密度聚乙烯(LLPE)和聚(乙烯-聚丙烯)共聚物(PEP)为试验材料。LLDPE/PEP体系提供了独特的机会，因为它可以在高温下相容。通过混合不混溶熔体和通过反应耦合来比较从可混溶熔体中沉淀产生的形态。这项研究应该产生新的和有用的形态，以及有效增容聚合物共混物的策略和定量模型。

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.