The effect of fullerene on the resistance to thermal degradation of polymers with different degradation processes

Investigations were made about the effect of fullerene (C-60) on the resistance to thermal degradation of high density polyethylene (HDPE), polypropylene (PP), polymethyl methacrylate (PMMA), and bisphenol A polycarbonate (PC) matrix by using thermogravimetric analysis coupled to Fourier transform infrared spectroscopy. The results showed that the influences of C-60 on the resistance to the thermal degradation of different polymers were dependent on their thermal degradation mechanism. The resistance to the thermal degradation of HDPE, PP, and PMMA were improved with the addition of C-60, especially for HDPE matrix, which indicated that the radical trapping played a dominant role. PP and PMMA released more gaseous products at high temperature by the random scission of C-C backbone; owing to the lower bond dissociation energy of C-C in the backbone for the existence of side chains. Meanwhile, the steric hindrance of side chains also made the radicals hard to recombine with each other and accelerated the random scission, leading to the less effect on the resistance to the thermal degradation of PP and PMMA. However, few changes of resistance to the thermal degradation were found in PC matrix with the addition of C-60 for its non-radical degradation mechanism.