Tensile and flammability properties of polypropylene-based RTPO/clay nanocomposites for cable insulating material

Nanocomposites of polypropylene-based RTPO with organically modified clays were prepared by melt compounding of three components, that is, polypropylene-based RTPO, maleic anhydride-grafted polypropylene oligomer (PPgMA), and organically modified clay. Their morphologies, tensile behaviors, and flammability properties were investigated. In the clay nanocomposites, the silicate layers were dispersed at the nanometer level, which was confirmed by X-ray diffraction and transmission electron microscopy. The tensile yield strength of nanocomposites containing 10 wt % clay exhibited 2.8 times higher value compared with that of neat resin. The combustion behavior of the nanocomposites was evaluated by measuring the heat release rate (HRR) using cone calorimetry. The peak HRR was lowered greatly and the char yield was very high compared with those of neat resin. However, these flame retardant properties of clay are not sufficient as a flame retardant used alone in cable applications.