Thermogravimetry as a method for investigating the thermal stability of polymer composites

Thermogravimetry was used to investigate the effects of different inorganic functional fillers on the heat resistance of polymer matrices. The kinetic parameters of thermal oxidative degradation were shown to depend on the po lymer, the chemical composition of the filler surface, the filler concentra tion, and the processing method, which determines the distribution of fille r particles in the polymer matrix. Magnetic fillers (carbonyl iron, and hex aferrites of different structural types) were shown to be chemically active fillers, increasing the heat resistance of siliconorganic polymers. Their stabilizing effect is due to blocking of the end silanol groups and macrora dicals by the surface of the filler and non-chain inhibition of thermal oxi dative degradation. In the case of fiber-forming polymers (UHMWPE, PVOH and PAN), most magnetic fillers are chemically inert, but at concentrations of 30-50 vol% they increase the heat resistance of the composite. Addition of carbon black increased the heat resistance of the thermoplastic matrix. Th e dependence of the thermal degradation onset temperature on the kaolin con centration in the polyolefin matrix exhibited a maximum. Analysis of the ex perimental results demonstrated the operating temperature ranges for differ ent composites, and their maximum operating temperature.