Melt rheology, morphology and mechanical properties of thermoplastic/rubber blends

Blends of PP and HDPE with EPDM and polyisoprene rubber(IR) formulated with CaCO3 filler were prepared by melt mixing. The rubbers were partially crosslinked with dicumyl peroxide (DCP). These blends were characterised analysing the effect of the thermoplastic/rubber ratio, filler and DCP content on the melt rheology, morphology, mechanical properties and accelerated UV ageing resistance. Melt viscosity of the blends showed an increase with rubber content. The use of CaCO3 filler reduced the elongation at break ind increased the melt viscosity of the blend. An improvement on mechanical properties and an increase on the melt viscosity were observed upon the incorporation of peroxide. Morphology of fractured samples of the blends, studied by scanning electron microscopy showed two phases.