Melt grafting of vinyltrimethoxysilane and water crosslinking of polypropylene/ethylene-propylene diene terpolymer blends

The melt grafting of vinyltrimethoxysilane (VTMS) onto polypropylene (PP)/ethylene-propylene diene terpolymer (EPDM) blends was studied. The effect of VTMS, EPDM and initiator concentrations on mechanical properties, melt flow index (MFI) and gel content of the modified PP/EPDM samples were investigated. The influence of coagents, i.e. styrene and trimethylolpropane trimethacrylate was also studied. Scanning electron microscopy (SEM) was used to observe the fractured surface of PP/EPDM and the modified PP/EPDM blends. The VTMS grafting reaction was in situ monitored using differential scanning calorimetry (DSC). Moreover, the thermal and crystallization behavior of VTMS-crosslinked PP/EPDM blends were studied by thermogravimetric analysis (TG) and DSC, respectively. It had been found that the thermal stability of VTMS-crosslinked PP/EPDM was improved. DSC measurements showed that the grafting reaction occurs from 170 to 220 °C and the crystallization temperatures increased compared with those of the untreated PP/EPDM.