A NEW METHOD TO DETERMINE THE AVRAMI EXPONENT BY DSC STUDIES OF NONISOTHERMAL CRYSTALLIZATION FROM THE MOLTEN STATE

The method reported in this paper is a simple means by which to determ ine the Avrami exponent, n, after cooling from the molten state of sem i-crystalline polymers. This determination, often drudgery, has been s ignificantly simplified, yet remains satisfactorily reliable. It is ba sed on the measurement, from an experimental crystallization exotherm, of the peak maximum and its inflexion points for different cooling ra tes. Results were tested against the Ozawa theory, and it was found th at our method was suitable for a slightly filled or unfilled thermopla stic polymer. However, neither our method nor the Ozawa theory apply w hen the matrix is reinforced with an efficient nucleating agent. (C) 1 997 Elsevier Science Ltd.