Morphological Transition of Isotactic Polybutene-1 Tetragonal Crystals: Optical and Transmission Electron Microscopy Observation

The morphology and lateral growth rate of isotactic polybutene-1 (it-PB1) have been investigated for crystallization from the melt over a wide range of crystallization temperature from 50 to 111.9°C. The morphology of it-PB1 crystals is rounded shape at crystallization temperatures lower than 85°C, while lamellar single crystals possess faceted morphology at higher crystallization temperatures; the kinetic roughening transition occurs around 85°C. The nucleation and growth mechanism for crystallization does not work below 85°C, since the growth face is rough. However, the growth rate shows the supercooling dependence derived from the nucleation and growth mechanism; the nucleation theory seems still to work even for rough surface growth. Possible mechanisms for the crystal growth of polymers are discussed