Method for studying orientation variations near surfaces in semicrystalline polymers

摘要

AbstractThe method of grazing incidence X‐ray diffraction provides a convenient means of examining crystal orientation close to the surface of a semicrystalline polymer. Since the sampled depth is governed by the choice of X‐radiation (via its absorption coefficient) and the angle of incidence, it is under the control of the experimenter. The method was tested and shown to be valid by applying it to a crossply laminated film of oriented polyethylene, of thickness 50 μm, in which the different crystal orientations on opposite faces of the film were known. Further experiments, with two polyethylene films of 20 μm and 40 μm thickness each extruded with differing rates of cooling on each surface, demonstrated the ability of the method to resolve spatial variations of orientation on this scale arising during manuf