Abstract
AbstractThe effect of pressure on the radiation‐induced solid state polymerization of acrylamide has been studied in a pressure range of 1 to 5000 atm. over a temperature region of 28 to 70°C. Rates of polymerization and molecular weights have been measured.It was found that the rate of polymerization is suppressed by pressure at the lower temperatures; in the contrary, the rate is accelerated near the melting point.On the other hand, it was also found that the rate of polymerization is suppressed by pressure in an initial stage of polymerization, while it is accelerated in a later stage of polymerization at the same temperature.The number of polymer chains obtained is not affected by pressure; it depends on the irradiation dose only. These results indicate that the pressure has very little effect on the rate of initiation but that the propagation rate constant is profoundly affected by pressure.The effect of the pressure on the solid state polymerization of acrylamide is attributed to the pressure dependence on the activation enthalpy (ΔH ‡) and the activation entropy (ΔS‡) of the propagation step.
Published Version
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