Regime II-III transition in isotactic polybutene-1 tetragonal crystal growth

The lateral growth rate and growth shape morphology of isotactic polybutene-1 tetragonal crystals were investigated for crystallization from the melt at temperatures of 68-101 °C. The growth rate of tetragonal crystals shows supercooling dependence derived from the nucleation theory, and a regime II-III transition is observed at temperatures of 77-82.2 °C. The morphology of single crystals is rounded below temperatures of 77-85 °C, while the growth shape has a faceted morphology at a higher crystallization temperature of 100 °C. The kinetic roughening transition occurs between 77 and 85 °C. The regime II growth mode is observed above 82.2 °C and proceeds by multiple nucleation on the faceted growth front, while the regime III growth mode is observed below 77 °C and proceeds by rough surface growth on the kinetically roughened growth front. The observed regime II-III transition can therefore be explained by the morphology transition of crystal growth shape.