Carbon Black-Filled PE/PP/EPDM Blends: Phase Selective Localization of Carbon Black and EPDM-Induced Phase Stabilization

Higher filler loading in incompatible polymer blends generally leads to catastrophic deterioration of physico-mechanical properties. This investigation reports effect of an elastomeric compatibili-zer on the mechanical properties of carbon black (CB) filled immiscible Polypropylene (PP)/Low density polyethylene (PE) blends. The composites were prepared by melt compounding of PE, PP, ethylene propylene diene monomer (EPDM) and CB in different proportions. Elongation at break for 30wt.% CB-filled PE/ PP (1:1) blends did not show any improvement up to 10wt.% EPDM addition, suggesting absence of any comptabilization effect of EPDM in CB-filled blends, whereas unfilled blends exhibited good comptabilization and about 200% improvement in elongation at break was observed at 10wt.% EPDM content. DSC studies revealed good interactions between PE and EPDM phases, and there was no reduction in the crystallinity of either PE or PP phases up to 50% EPDM loading. The phase inversion was observed in 50-75wt.% EPDM loading. The micromechanical modeling of the composite suggests selective incorporation of CB in PE and EPDM phases. The results have been explained in the light of the percolation of carbon black in different phases and the role of EPDM as a compatibility modifier of PE and PP phases.