New (PP/EPR)/nano-CaCO3 based formulations in the perspective of polymer recycling. Effect of nanoparticles properties and compatibilizers

Phase structure of composite polypropylene (PP)/ethylene-propylene-rubber (EPR)/coated nano-CaCO3 composites, used in the manufacture of bumpers, with and without compatibilizers has been investigated using scanning electron microscopy (SEM), dynamic mechanical analysis (DMA) mechanical tests, and differential scanning calorimetry (DSC). Blends of various compositions were prepared using a corotating twin-screw extruder. The experimental results indicated that the dispersion of nanoparticles in (PP/EPR) depends on their surface (stearic acid and fatty acid coatings). In both cases, the final morphology is the core-shell structure in which EPR acts as the shell part encapsulating coated nano-CaCO3. In this case, EPR-g-MAH copolymer does not improve the interface between (PP/EPR) and nanoparticles but PEP propylene ethylene copolymer should be preferentially localized at the interface of PP and (EPR/nano-CaCO3) phases generating an improved adherence, which will ensure a better cohesion of the whole material. According to the nature of the compatibilizers and surface treatment, it is believed that the synergistic effect of both the EPR elastomer and CaCO3 nanoparticles should account for the balanced performance of the ternary composites. Copyright (C) 2009 John Wiley & Sons, Ltd.