Periodically modulated driving force applied to polymer crystallization in a visco-elastic measurement with temperature modulation

The method of “periodically modulated driving force” has been applied to the kinetics of polymer crystallization examined by a dynamic visco-elastic measurement with temperature modulation. The dynamic elasticity obtained by the measurement shows a strong nonlinearity in its dependence on the degree of crystallinity, and hence the simple time derivative does not represent the rate of crystallization. With the application of periodic modulation in temperature and the examination of the response of crystallization kinetics appearing in the modulation in the elasticity, it has been shown that the temperature dependence of growth rate can be determined even with the nonlinear dependence of this quantity. The method is applied to the crystallization of polyethylene, poly(vinylidene fluoride) and isotactic polypropylene. The agreement with the results from the direct measurement of growth rate by optical microscopy is satisfactory.