Influence of crystallization conditions on single crystal formation

Abstract

The effects of solvent. molecular weight of polymer and its distribution. and crystallization temperature on the formation and structure of single crystals from solution are discussed. With respect to the solvent effect, the intrinsic viscosity and lamellar thickness of crystals formed were investigated with various solvents as functions of temperature. It is pointed out that the solvent effect primarily reflects the equilibrium dissolution temperature and. more-over, affects the surface roughness or the conformation of fold portion which relates to the numerical value of the surface free energy. Concerning the effects of molecular weight and its distribution, measurements were carried out on the lamellar thickness, thickness of fold-containing surface, density, etc., with single crystals formed and taken out at constant temperatures. It is pointed out that, with sharp fractions of low molecular weights and at lower supercooling, we can obtain assembly of single crystals with higher density and larger thickness. © 1972, Walter de Gruyter. All rights reserved.