Compatibilizing effect of natural rubber-g-poly(methyl methacrylate) in heterogeneous natural rubber poly(methyl methacrylate) blends

The morphology and properties of heterogeneous poly(methyl methacrylate)/ natural rubber blends have been modified by the addition of a graft copolymer of natural rubber and poly(methyl methacrylate) (NR-g-PMMA). The morphology has been studied as a function of copolymer concentration. A sharp decrease in the dispersed domain size was observed by the addition of a few per cent of the copolymer followed by leveling off at higher concentrations. The compatibilizer increases the interfacial adhesion by the formation of micro-bridges with the matrix. The effects of homopolymer molecular weights, processing conditions, and mode of addition on the morphology of the dispersed phase have been investigated. The experimental results are compared with the theoretical predictions of Noolandi and Hong. Attempts have been made to explain the conformation of the graft copolymer at the interface. The changes in mechanical properties of the blends as a result of the addition of the compatibilizer were related to the morphology of the blends.