Pressure effect on the radiation‐induced solid state polymerization of β‐propiolactone

Abstract

AbstractThe effect of pressure on the radiation‐induced solid state polymerization of β‐propiolactone has been investigated in the range of 1 to 5000 atm over a temperature region of −196 to −78°C. Rates of polymerization, viscosities, melting points and infrared spectra have been measured.It was found that the rate of polymerization is accelerated by pressure at temperatures below −98°C, and that the activation energies change for polymerizations at 1 and 5000 atm from 0.01 kcal/mole to 0.18 kcal/mole.The pressure effect was discussed from the point of initiation, propagation and termination reactions, taking the effect of additives on the polymerization into consideration.It may be concluded from the study that the effect of pressure on the propagation reaction is most important and the pressure effect is not only due to the change of the activation enthalpy but also the change of the activation entropy.