Simultaneous Measurements of Stress and Infrared Dichroism of Inflated Polyethylene Films

The change of stress andinfrared dichroism of inflated polyethylene films during elongation and stress relaxation were measured simultaneously. Infrared dichroisms were recorded by means of the differential method reported previously. A remarkable decrease in absorbance at 730 cm- ' and a very small change in specific gravity during elongation were interpreted as the result of degradation of the crystallites into smaller ones by stretching, total crystal content remaining almost constant. It was found that the instan-taneously stretched films showed stress relaxation and gradual recrystallization after rapid degradation. Orientations of crystalline polymer during elongation and relaxation were discussed by using orientation functions