Crystallization kinetics, Avrami analysis, and fast-scanning DSC of polymers
Akihiko Toda
Abstract
The kinetics of polymer crystallization from the melt is described as the process of nucleation and growth of crystal domains. In this review, the Kolmogorov–Johnson–Mehl–Avrami (KJMA) model is used to investigate the kinetics in detail. In particular, the importance and wide applicability of the concept of extended volume are emphasized. The so-called Avrami analysis based on the KJMA model is applied to describe isothermal crystallization where the rates of nucleation and growth are supposed constant. Scattering from crystallizing samples is also analyzed using the correlation function proposed by Sekimoto based on the KJMA model. In contrast, for non-isothermal crystallization, the Ozawa method and the Nakamura method are applied to investigate crystallization by constant rate cooling and a non-constant rate, respectively. Moreover, recent developments in the Ozawa method are also explained. As a specific example, recent studies of the Avrami analysis for isothermal crystallization using a chip-sensor fast-scanning calorimeter are reviewed in terms of the crystallization kinetics of poly(butylene terephthalate) examined over a wide temperature range down to the glass transition temperature. This includes a discussion on the decelerating effect of rigid amorphous fraction on crystallization, the formation mechanism of nodular crystallites, and the application of the original Avrami model proposed 80 years ago, which is suitable for the quantitative assessment of the effects of nucleating agents.