Some aspects of thermal decomposition of polyoxymethylene and irradiated polyoxymethylene

Abstract

AbstractThe thermal decomposition of polyoxymethylene and irradiated polyoxymethylene in vacuum was carried out and the kinetic aspects of thermal decomposition discussed. Although decomposition of low viscosity polyoxymethylene followed a pattern in which log (polymer residue) was roughly linear with decomposition time, the high‐viscosity polyoxymethylene which was obtained by the post‐polymerization of irradiated solid formaldehyde showed the two components different in stability. However the concentrations of the components depended on the decomposition temperature. After the thermal decomposition, the sample could not be further stabilized by acetylation, while this initial polymer could be highly stabilized by acetylation. The irradiated polymer also could not be thermally stabilized by acetylation, though the first component of the irradiated polyoxymethylene disappeared after acetylation. The components of the polymer irradiated at 100°C., ∼4 Mr (ηsp/c = 0.23) showed three components the concentrations of which are independent of decomposition temperature. In irradiation at room temperature, or in the case of irradiation by the electron beams from a Van de Graaf generator at a high dose rate, the evacuation at 100°C. of the irradiated sample after irradiation disclosed the clear dependence of formation of stable polymer on dose, and the formation of three components which are independent of the decomposition temperature.