PHYSICAL-PROPERTIES OF MODEL GRAFT-COPOLYMERS AND THEIR USE AS BLEND COMPATIBILIZERS

The present investigation pertains to the structure-property relations hips of highly structured graft copolymers. The specific model graft c opolymers are based on an elastomeric backbone, i.e., poly(ethyl acryl ate), and monodisperse thermoplastic grafts, i.e., polystyrene. The sy nthesis of these graft copolymers is based on the free-radical polymer ization of ethyl acrylate and an anionically polymerized polystyrene m acromonomer. It is clearly demonstrated that grafts significantly enha nce tensile properties. The level of improvement is directly related t o the graft level, i.e., number of grafts/chain, and graft molecular w eight. In addition, blending these graft copolymers into their respect ive homopolymer mixture results in a mechanical performance strikingly dependent on the molecular characteristics of the graft copolymer. Fo r example, tensile strength is maximized at a level between one and tw o grafts per chain. This result parallels observations noted in blend compatibilization using diblock and triblock copolymers. It is also de monstrated that using mutually grafted copolymers produces an interest ing variety of compatibilized ternary (or higher) component blends. (C ) 1994 John Wiley & Sons, Inc.