Degradation of polytetramethylene oxide. I. Thermally‐induced

The thermal degradation of polytetramethylene oxide has been examined in detail. The polymer contained weak links which led to facile chain scission on heating. (50 to 150°C.). The activation energy of this degradation process in xylene solution is 13.3 Kcal/mol. The available evidence indicates that the weak links are hydroperoxide groups formed in the presence of air. These groups could be destroyed by heating in vacuum, the resultant degree of degradation of the polymer depending on the number of hydroperoxide groups present. Measurements of the intrinsic viscosity of polytetramethylene oxide, freed from weak links, showed that the polymer underwent random chain scission at elevated temperatures according to the equation: The exponent, α, of the KUHN‐HOUWINK equation was thus determined to be 0.75 for the polymer in benzene at 20°C. Analysis of the molecular weight changes occurring during degradation at various temperatures showed that the chain scission process obeyed first order kinetics and could be expressed by the rate equation: This result is compared with activation energies obtained by thermogravimetry in air and vacuum.