Rheological - Morphological Relationship in Immiscible and Reactively Compatibilized SAN/EPDM Blends

摘要

In immiscible blend of SAN and EPDM a coarse unstable morphology is formed. Viscosity of the blend of these highly viscous components at moderate shear stress drops below that of individual components due to weakness of shear planes at the interphase. In reactive blends, formation of SAN-g-EPDM at the interface causes fine stable droplet morphology and viscosity increases to levels between those of the individual pairs. Prediction of the Favis equation shows at 17 wt% of graft, the size of dispersed phase would be minimum which is in agreement with obtained results. The relaxation spectra of the uncompatibilized blends shows a combination of the relaxation spectra of phases and an additional relaxation time associated with the interface under tension. The interfacial tension of the blends determined via making use of the Palierne and the Choi-Schowalter models shows minimum value at 1 phr initiator. The droplet morphology is changed to composite in two step blending method with viscosity ratio near to unity and Luperox content of 1 phr. A higher apparent volume fraction of EPDM in the blend with composite morphology which has been also obtained by Kerner equation is an indication of the evolution of the composite morphology.