Miscibility Studies of PVC / ELNR Blends

摘要

Liquid natural rubber of two different molecular masses, viz., $overline{text{M}}_{text{W}} = 4900$ and 9500, each with epoxidation of 20 and 50 mol % (L-ELNR-20, L-ELNR-50, and H-ELNR-20, H-ELNR-50) were prepared and blended with polyvinyl chloride (PVC). Miscibility of these blend systems was studied with special reference to blend ratio, mol % of epoxidation and effect of molecular mass of the liquid rubber by various techniques such as stress – strain measurement, SEM studies and DSC analysis. It was observed that PVC/L-ELNR-50 and PVC/H-ELNR-50 systems were homogenous and miscible compared to PVC/L-ELNR-20 and PVC/H-ELNR-20 blends and the maximum modification in properties was found for the former systems. Results of blends with 20 mol % epoxidised liquid rubber showed that the components are only partially miscible and hence they are heterogeneous systems. Miscibility achieved with an increase in mol per cent epoxidation of the liquid rubber is explained on the basis of the higher polar interaction between the blend components. Analysis of the blends also revealed that the lower molecular mass epoxidised rubber is aiding better property modifications than the higher molecular mass rubber. This is explained by the fact that rubber with lower chain length provides greater penetration into the PVC interstices enabling better solubilisation of the PVC segments.