Crystallite orientation in extruded polyethylene film

摘要

AbstractThe complete orientation distribution of theaandbcrystallographic directions have been measured for a series of tubular extruded polyethylene films as a function of blow ratio. The use of pole figures as a means of representing orientation is emphasized and it is shown that the usual technique of using flat plate x‐ray diffraction photographs can lead to erroneous conclusions. Increasing the blow ratio has a distinctly different effect upon the orientation of high density polyethylene film in comparison with low density polyethylene film. In contrast with previously published information our results clearly indicate that thecaxis does not orient preferentially perpendicular to the extrusion direction. In particular, it is shown that one cannot in general deduce the maximum in the orientation distribution of thecaxis from qualitative estimates of theaandbaxes distributions. The ultimate tensile strength, elongation, modulus and tear strengths of these films were measured and the results correlated with the orientation of the crystallo graphic direction