Study of rheological and mechanical properties of ternary blends of iPP/LDPE/EPDM

Compatible blends of isotactic polypropylene (iPP)/low density polyethylene (LDPE)/ethylene-propylene-diene monomer (EPDM) were prepared by reactive blending in the presence of dicumyl peroxide (DCP). The blends were characterized using different techniques: dynamical rheological analysis (DRA), differential scanning calorimetry (DSC), optical microscopy (OM) and scanning electron microscopy (SEM), dynamical mechanical thermal analysis (DMTA), viscosity and impact strength, to evaluate their properties. Results revealed that the presence of the peroxide in LDPE/EPDM blends gives rise to crosslinking reactions, as is the case in iPP/LDPE/EPDM blends. However, in the latter case, scission reactions of the iPP component also take place. As a consequence of the whole process, morphological changes arise mainly in the amorphous regions, without affecting the degree of crystallinity of the components. The mechanical properties of the blends are consequently improved, due to the crosslinked network thus formed in the blends.