COMPOUNDING AND MORPHOLOGY OF NYLON ETHYLENE-PROPYLENE RUBBER REACTIVE AND NONREACTIVE BLENDS

The processing behavior and morphology are investigated for nonreactiv e and reactive nylon/ethylene-propylene, rubber blends. The nylon (PA) is a partially aromatic amorphous nylon with amine termination. The r ubbery phases are an ethylene-propylene rubber (EP) and a similar ethy lene-propylene rubber (EP-MA) with 0.7% grafted maleic anhydride. The nonreactive PA/EP blends show poor interfacial adhesion between the tw o phases. The reactive PA/EP-MA blends show excellent adhesion and muc h smaller dispersed phase domain sizes. The interfacial chemical react ion affects several separate parameters which influence the size of th e dispersed phase: the formation of a copolymer at the interface which reduces the interfacial tension; different rheological properties of the modified and unmodified rubbers; the effect of the interfacial rea ction on the rheology of the blend; changes in process parameters die to the effect of the interfacial reaction; reduction in the rate of pa rticle-particle coalescence due to the presence of the copolymer at th e interface; as well as other effects. A semi-empirical relationship i s used to separate the effects of phase rheology and applied mixing st ress.