Changes in the fold content due to drawing and annealing of polyethylene

Abstract The fold content of polyethylene, which varies with drawing and/or annealing, was evaluated by an IR method. Solution-grown n-paraffin single crystals are assumed as a standard material containing no folds, while solution-grown single crystals of polyethylene are assumed to contain one unit of fold content. In preparing mixtures of these two standard materials, the following equation is obtained: A1304—0.49A1350 = 0.14Cf A1304 and 0.49A1350 are the absorbances of the IR band at 1304 and 1350 cm-1, respectively. The fold contents (Cf of polyethylene specimens prepared under various conditions are estimated in terms of this equation. In the drawing process of polyethylene films, Cf decreases abruptly in the region of draw ratio of 2 ∼ 3 and gradually decreases with further drawing when drawn along the machine direction. The content of remaining folds are quite different between specimens drawn along the machine direction and those drawn transversely to this direction. This fact reflects the differe...