ISSN:
0449-2951
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Continuous structure change in the necking part of the cold-drawn polyethylene has been examined by the wide- small-angle x-ray diffractions. A specially designed microbeam x-ray camera which permits both wide- and small-angle diagrams to be obtained at the same position at the same time was used. With increasing draw ratio, along the center axis of the specimen, first the crystallites are aligned with the a axes perpendicular to the draw direction; this is followed by a gradual orientation of the c axis to the draw direction. On the other hand, an isotropic ring-shaped small-angle halo continuously changes to an elliptical halo with its minor axis on the meridian. After this stage, a meridional scattering in layer streaks appears superposed on the flat elliptical halo, then the elliptical halo disappears and the layer streaks on the meridian remain, and finally the quadrant meridional scattering appears as diffuse layer streaks with intensity maxima on both sides of the meridian. On the stream line, nearly the same variations of the wide- and small-angle diagrams as those on the center axis are observed; however, the meridian of each diagram is not parallel to the draw direction but coincides with the tangent of the stream line at each irradiated position. The stream line was conventionally defined so as to divide the y coordinates from the center axis to the surface at every point on the line into the same ratio. One characteristic diagram along the stream line is a small-angle oblique two-point pattern, appearing as off-meridian layer streaks. From each wide-angle diagram, the average orientation angle between the c axis and the meridian, degree of crystallite parallelity, and the apparent crystallite size were estimated. The Bragg distance, identity period along the meridian, and the azimuthal angle on the film between the meridian and the direction from center to the diffraction peak were determined by the small-angle scattering. In considering these results, a series of plausible models for continuous structure change in necking is presented.
Additional Material:
14 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1964.100020435
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