Reactive compatibilization of SAN/EPR blends. 1. Dependence of the phase morphology development on the reaction kinetics

SAN containing 20 wt % of reactive SAN-X has been melt blended with EPDM co ntaining 50 wt % of EP chains grafted by maleic anhydride (EP-g-MA). Two ty pes of reactive groups (X) have been attached to SAN (2 mol % of X), i.e., a primary amine and a precursor of it at the processing temperature, i.e., a carbamate. The SAN/rubber weight composition was kept constant at 75/25. The development of the phase morphology from pellet-sized rubber particles to dispersed submicrometer droplets has been investigated during reactive m ixing for the two types of reactive SAN and has been found to depend on the interpolymer reaction rate and thus on the relative reactivity of the amin e and the carbamate groups attached to SAN toward the maleic anhydride func tion of EP.