Compatibilization Effects in SAN/EPDM Blends Prepared by Reactive Extrusion

Abstract

Styrene-acrylonitrile copolymer (SAN) and ethylene-propylene-diene terpolymer (EPDM) are known as immiscible polymers but their blends are interesting for application because of good stability in use. The blending of SAN and EPDM by reactive extrusion under various conditions is studied. SAN/EPDM blends are investigated to obtain improved SAN/EPDM miscibility and to determine the effect of rubber (EPDM) on the polymer morphology and mechanical properties. The first series of samples is prepared with different ratios of SAN and EPDM, the second series with addition of high impact polystyrene (HIPS) as a compatibilizer, and the third series with free radical initiators α,α '-di(t-butylperoxy)diisopropyl-benzene (Peroximon F40) and 2,2-azo-di-(2-acetoxy) propane (Luazo AP). The blends are characterized by determination of mechanical properties. Then the blends are separated on its components: SAN, EPDM, graft (EPDM-g-SAN), and gel to elucidate the extrusion process. The identification of extracted polymers has been made by IR spectrophotometry. Scanning electron microscopy (SEM) is used to observe the morphology. The dominant grafting reaction, which improves compatibility, is observed in blends prepared with HIPS compatibilizer and with Peroximon F40 initiator.