Some orientation studies on blown polyethylene films by infrared spectroscopy

Abstract

SynopsisInfrared 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 a t 1303,1352, and 1368 cm-', 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 a t 1080 cm-', 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 a t 720 and 730 cm-I and the tear strengths and balances of the films with low-stress orientation.

Improving Barrier Through Orientation in Processing

“…The effect of various processing methods on the morphology of polyethylene has been extensively studied by several authors [3][4][5][6][7][8][9][10][11][12][13]. The earliest work on polyethylene was that of Peterlin and co-workers [3][4][5][6][7] which produced the basis for his microfibrillar model of the morphology of highly oriented films.…”

“…One definitive study by Maddams and Preedy [9][10][11] described the morphology of the films using x-ray diffraction. The use of infrared was added by McRae and Maddams [12] to further delineate the orientation.…”

Biaxial orientation in LLDPE films: Comparison of infrared spectroscopy, X‐ray pole figures, and birefringence techniques

“…The most widely used biaxial processes for films are the standard film blowing process (for various polyethylenes, PE), double bubble process (for polypropylene, and linear low-density polyethylene, LL-DPE), and cast film biaxial orientation or tentering (high density polyethylene, HDPE, and polypropylene). All these processes impart a certain degree of orientation to the polymers, which enhances many of their properties [1][2][3][4][5], particularly mechanical, impact, barrier, and optical. Biaxial orientation has the added advantage of allowing this en-hancement in both directions.…”

Biaxial orientation in HDPE films: comparison of infrared spectroscopy, X-ray pole figures and birefringence techniques

“…In fact, orientation of polymers enhances many of their properties [1][2][3][4][5], particularly mechanical, impact, barrier and optical. Biaxial orientation has the added advantage of allowing this enhancement in both directions.…”