Crystallization of polyethylene from solution was studied under shear strain. Making use of a rotational viscometer, a steady state flow of the solution was achieved. The crystals grown from solution under shear strain exhibited entirely the same features as those grown under no shear strain (the single crystals usually observed). Namely, the molecular orientation in the solution facilitates ctystallization but does not affect the morphology of the resultant crystals. It was found, however, that fibers were produced from 0.1% solutions and films from 1% solutions, both having grown from a few points on the rotating inner cylinder of the viscometer. These films consist of fibers which are similar to those grown from the 0.1% solutions. Electron microscopy revealed that the lamellae were piled up along the direction of the shear and aligned perpendicularly to the shearing direction. It is concluded that this sort of texture would be nothing but a quite general texture obtained when crystallization takes place under molecular orientation. It is suggested that this texture results from a bi-components crystallization where some polymer molecules crystallize first into the extended form and then the other molecules deposit into the chain folded lamellae on the substrate of the extended chain crystals. In order to confirm this assumption, measurements of D S C thermograms, specific heat, mechanical tan δ and the tensile moduli from the velocity of the propagation. of a pulse along the fibers were made for the fibers and the films grown from the solution. All the results showed a rather low crystallinity and low melting temperature of the fibers and films. In the D S C thermograms, moreover, no distinct peak was observed at the temperatures corresponding to the extended chain crystals. Also from the morphological studies no evidence has been observed on the bi-component crystallization in question. It was postulated that fibrillar structures observed did not exist when the crystallization took place but were produced by mechnical deformation of the lamellae, which occures after the precipitation of fibers and films.
