Non-isothermal crystallization of poly(vinylidene fluoride) during cooling at various rates was investigated by differential scanning calorimetry (d.s.c.). The data were analysed with the new model of non-isothermal crystallization developed by Ziabicki. The application of this model to experimental data allows separate determination of the rate of steady-state crystallization and the effect of time-dependent mechanisms. It was shown that the measured crystallization rate is higher than the rate of the steady-state process. It is probable that the accelerating factor is the athermal mechanism predicted by Ziabicki’s model. The analysis presented of non-isothermal crystallization data gives the possibility of determining the steady-state crystallization rates over the whole temperature range of the crystallization process. The previous method of determination of crystallization rate from isothermal measurements applied to polymers with high crystallization rate, like poly(vinylidene fluoride) or polyethylene, can provide data only for a narrow temperature range lying at the end of the upper branch of the crystallization curve.
Посилання на статтю:
Steady-state process and time-dependent effects in non-isothermal crystallization of poly(vinylidene fluoride) / Paweł Sajkiewicz // Polymer. – 1999. – N 40. – P. 1433–1440.