Radiation‐induced seeded copolymerization of tetrafluoroethylene with propylene. I. Effects of agitation and dose rate

Abstract

AbstractSeeded copolymerization of teterafluoroethylene with propylene by radiation was studied by semibatch experiment at a constant pressure of 25 kg/cm2, a temperature of 40°C, and at various dose rates and monomer compositions in polymer particles. The polymerization rate and polymer molecular weight are in the ranges of 5.6–58.7 g/h.L‐H2O and 4.6 × 104–1.6 × 105, respectively. The polymerization rate increases with agitation speed up to 300 rpm and slightly decreases above 500 rpm. The polymer molecular weight is the highest at 300 rpm. The polymerization rate and polymer molecular weight increase with tetrafluoroethylene fraction. At lower tetrafluoroethylene fraction, the polymerization rate is proportional to the 0.7–0.9 power of the dose rate and the polymer molecular weight is almost independent. The dose rate effects are explained by considering that first‐order termination by degradative chain transfer to propylene is predominant at a lower tetrafluoroethylene fraction. Decrease in the dose rate dependence of the polymerization rate and increase in that of the polymer molecular weight with the tetrafluoroethylene fraction are due to the increase in second‐order termination by recombination.