CRYSTALLIZATION KINETICS OF POLYMER-SOLVENT SYSTEMS .2. EXPERIMENTAL-VERIFICATION OF THE MODEL

A theoretical model for the description of crystallization kinetics of a polymer from solution was suggested in a previous paper [1]. In thi s work, this model was verified using a polyphenylene sulfide-tetramet hylbiphenyl system (PPS-TMBP) as an example. The theoretically predict ed particle number density was compared with that resulting from the A vrami equation by analyzing the experimental data obtained by isotherm al differential scanning calorimetry. Optical and scanning electron mi croscopies was also applied to obtain the values of the particle numbe r density. Size particle distribution was calculated in accordance wit h the proposed model to study the number of particles with sizes excee ding the resolving power of the optical microscope. For the given expe rimental conditions (the dissolution temperature range is 543-563 K, t he polymer concentration in a solution is 40 wt %), the theory propose d in [1] predicts the formation of particles that cannot be observed i n an optical microscope. This agrees with our observations, whereas th e Avrami equation predicts the presence of particles that are visible in an optical microscope. The density of particle number, obtained by scanning electron microscopy at a dissolution temperature T-d = 573 K, is in the range (0.7-1.4) x 10(9) cm(-3). The model suggested in [1] predicts the value of the particle number density just in this range, whereas the Avrami equation yields a much smaller value. Thus, the mod el proposed in [1] describes the crystallization kinetics in the polym er-solvent system much better than the Avrami equation.