Reactive compatibilization of SAN/EPR blends: Effect of rubber content and reactivity of the SAN functional groups

SAN containing 20 wt.-% reactive SAN-X was melt blended with EPDM containing 50 wt.-% maleic anhydride EPR grafted chains (EP-g-MA). The rubber content was changed from 15 to 80 wt.-%, and 2 types of reactive groups (X) were attached to SAN (0.028 mol X/ wt.-%), i. e. primary amines and carbamates which are primary amine precursors at the processing temperature. Phase morphology, tensile properties and impact strength depend not only on the rubber content but also on the relative reactivity of the amine and the carbamate groups towards maleic anhydride, in a strong dependence on the reaction rate and the reaction completeness. The dispersion mechanism has been discussed, including formation of sub-inclusions. Dependence of the impact resistance on the rubber phase content for non-reactive blends (□) and blends modified by SAN-NH2 (;) and SAN-carb (o), respectively.