It was shown that the fibrous crystals of isotactic polybutene-l crystallized from solution under shearing stress are also composed of the central threads with an extended chain character and the epitaxally deposited lamellae with a folded chain character. The characteristic behaviors in this polymer exist in; (1) that the resulting crystals possess the hexagonal modification of form 1'; (2) that at low polymer concentrations the lamellar crystals with an orthorhombic modification of form Ⅲ are precipitated in similar fashion to the case in the absence of stirring; (3) that the morphology in surface replica
of thick deposited film is very similar to that of melt extruded polyethylene film crystallized in a highly stressed state.