Features of thermooxidation behavior of polypropylene blends with rubbers of different nature

Thermooxidation resistance of polypropylene (PP) blends with rubbers of dif ferent nature, showing a weight loss 5-20 times smaller as compared to that of the individual PP was studied using an isothermal thermogravimetric tec hnique at 280 degrees C. It is shown that the thermal stability of a blend is independent on the component ratio in a wide concentration range (from 8 0 : 20 to 20 : 80 w/w). The polymer stabilization with respect to thermal d egradation is provided by the formation of a protective layer on the surfac e of monolithic particles, hindering oxygen diffusion to the last thermosta ble component (PP). it is suggested that the products of degradation of bot h blend components participate in the formation of this layer. The above pr ocesses most likely occur in the interphase: layer and a decisive role play s the chemical affinity of a rubber to PP.