Single Crystal Texture Research Articles

The thermal expansion of single-crystal texture linear polyethylene between 0 and ?190� C

Thermal expansion of linear polyethylene in both macroscopically isotropic and single-crystal texture forms was measured between 0 and −190° C. Results are interpreted by treating the semicrystalline polymer as a simple two-phase composite material. The single-crystal texture specimen was prepared by drawing with constant width at 121° C followed by annealing, giving unique preferred orientations of each of the three crystal axesa, b andc (c parallel to the draw directionZ, a parallel to the sheet normalX andb parallel toY, the normal to the thin edge of the sheet). The thermal expansions parallel toX, Y andZ follow approximately the thermal expansions ofa, b andc vectors of the unit cell as determined by X-ray diffraction. An attempt is made to allow for the contribution to thermal expansion from amorphous regions, representing the oriented solid by a simple model in which crystal and amorphous regions are coupled in series in the draw direction and in parallel in the two perpendicular directions. This analysis requires the thermal expansion of amorphous polyethylene which was obtained by extrapolation of thermal expansion measurements on ten isotropic specimens whose crystal volume fractions lay between 0.81 and 0.49. It was observed that the single crystal texture specimen of crystal fraction 0.80 and an isotropic specimen of the same crystal fraction on cooling changed in volume by equal amounts. This fact together with the observation that the thermal expansion parallel toY of the single crystal texture specimen is equal to that of the isotropic specimen leads to important conclusions concerning the existence of microstresses in linear polyethylene caused by a change of temperature.

Crystal Texture of LiF Single Crystals by X-Ray Technique

By the convergent X-ray beam method with transmission type monochromator by Kato (Acta Met. 5 (1957) 237), crystal texture of as-grown LiF single crystals is studied for thick as well as thin specimens. It is found that the topographic as well as the goniometric information is obtainable on a diffraction photograph by the profitable use of the convergent incident beam. Observation of surface texture is also carried out by etching method to interpret more thoroughly the fine structure of diffraction pattern.

A new photographic method for studying the texture of large single crystals

A new photographic method for studying the texture of large single crystals

The texture of single crystals of brucite

The texture of single crystals of brucite

Macromolecular Compounds. CCXVI. Determination of the Lattice of Rubber

Abstract In an earlier work a rotating crystal diagram, three different Schiebold-Sauter (rotating goniometer) equatorial diagrams and two different photomicrographs of the same sample of a single crystal were described and shown to be conclusive proof of the single-crystal texture of the sample under examination. If, in their work on the same subject, Meyer and Mark had likewise taken numerous photographs of different kinds, instead of a single photographic film, a comparison of the various photographs would speak for itself. In taking his rotating crystal goniometric photographs, the present author used uniformly thick, frozen small cubes of rubber, the intensities in the reflections of which were the same in all directions. On the contrary, in the photographs of Meyer and Mark, a stretched film of rubber, which reflected considerably less uniformly than did the samples used by the present author, was photographed at rest and therefore without being rotated. Although Meyer and Mark agree to the interference 300, they maintain that this does not explain in any way the appearance of reflection A2.