Abstract
The thermal decomposition behaviors of polystyrene, its derivatives, and polyolefins were investigated by thermogravimetric method in which gas chromatography and/or mass spectrometry are interfaced. Decomposition products of polystyrene and poly(p-methyl styrene) were found to be predominantly monomers with a few dimers. In the case of the poly(α-methyl styrene), the monomer was observed as the predominant species and the amounts of other products were quite negligible. As for the formation ratio of dimer to monomer, the observed ratios for polystyrene and poly(p-methyl styrene) were all less than those reported in the literatures obtained by isothermal method. Dimers were detected only in a high temperature range, where the mass loss was seldom to occur. Since the formations of the most of dimers are considered to occur at the completion of the decomposition reactions, the most of dimers are produced from secondary reactions in the case of polystyrene and its derivatives. The decomposition products of polyolefins were mixtures of hydrocarbons. Especially, the major decomposition products of polyethylene were hydrocarbons of C10-C14, and the monomer was not observed. From considering the molecular structures of cyclic products, it was seen that the secondary reaction(s) occurred to form the complicated final products in the case of polypropylene. The relation between the decomposition temperature of polymers and the ceiling temperature of their monomers was noted. In case that the thermal decomposition temperature range is above the ceiling temperature, a lot of monomer is produced, while if it is below the ceiling temperature, the monomer is rarely observed.
