DETERMINATION OF NUCLEATION RATE IN POLYMERS USING ISOTHERMAL CRYSTALLIZATION EXPERIMENTS AND COMPUTER-SIMULATION

Within the frame of overall kinetics of crystallization, polymer crystallization is characterized by only three parameters: the initial density of potential nuclei N0, their activation frequency q and the growth rate G. The growth rate G is rather easy to measure, whereas the nucleation parameters are generally unknown. Our purpose is to determine both N0 and q using experimental isothermal two-dimensional crystallizations and computer simulation. Both these parameters are deduced from the rate of appearance of spherulites expressed as a function of the transformed surface fraction. The activation times of the spherulites are deduced from the shape of the boundaries between spherulites at the end of the transformation. When the growth rate G is known, the evolution of the transformed surface fraction is rebuilt using a computer simulation, so that only one observation of the final stage of the crystallization is needed.