AbstractInfrared dichroic measurements have been made on a number of blown polyethylene films for which x‐ray diffraction pole figure studies are reported in the three preceding papers; they complement them in some respects, and lead to several conclusions. Gauche chain conformations in loose chain folds in amorphous regions, characterized by bands at 1303, 1352, and 1368 cm‐1, show appreciable orientation in films with high‐stress orientation but very little with low‐stress orientation. Conversely, extended tie chains in amorphous regions, assessed by the band at 1080 cm‐1, are appreciably orientated with the more normal type of low‐stress film but not with high‐stress films. It is therefore possible, rapidly and inexpensively, to distinguish between the two types of orientation. The method for studying the orientation of extended tie chains is capable of further development. There is probably an empirical correlation between the dichroic ratios at 720 and 730 cm‐1and the tear strengths and balances of the films with low‐s
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