High‐pressure phases in polymers. I. Spherulitic growth kinetics in cis‐polyisoprene

This is the first paper in a series dealing with the crystallization of high polymers at elevated pressures. Through an extension of the thin‐film technique using osmium tetroxide staining, the measurement of lamellar growth kinetics at high pressures as well as the observation of micromorphological changes has proved possible. Three different morphological species of cis‐polyisoprene have been detected in the pressure–temperature plane. A review is given of the conditions governing their formation and the growth kinetics of lamellar crystals are discussed in detail. Secondary nucleation theory is obeyed, the major effect of pressure being to alter the kinetics through the thermodynamic transitions. Variations in lamellar thickness with pressure may be explained simply in terms of the elevation by pressure of the equilibrium melting point.