Some aspects of nonisothermal crystallization of polymers. II. Consideration of the isokinetic condition

Abstract

In the previous paper a practical method has been applied for an analysis of non-isothermal crystallization in terms of data of isothermal crystallization. The fundamental equation was written on the assumption of the isokinetic conditions in the following form: where X(t) is the degree of phase transformation at time t, and n is the Avrami index determined in the isothermal experiments; K(T) is connected with the crystallization rate constant of the isothermal crystallization, k(T), through the relation K(T) = k(T)1/n. The equation is derived on the basis of the well-known theory of phase transformation. Experiments of nonisothermal crystallization of high-density polyethylene were carried out under various cooling conditions. The change in crystallinity during the process was followed by using the above equation in the course of the primary crystallization. A procedure of the analysis of the whole, including both the primary and secondary processes, is suggested as an eminently practical one on a more general assumption.