A study of structural changes taking place upon orientation and in the process of annealing oriented polymers

The reversible character of the deformation of polyethylene films containing well‐defined spherulitic structures was shown by optical microscopy. The sizes of crystalline and defect (amorphous) regions were derived from theoretical calculations based on the data of small‐angle x‐ray diffraction. The specimens were obtained by annealing them in the stretched state. The dependence of the long period on the annealing temperature for oriented fibers of polyethylene, polycaproamide, and polypropylene was found. The possibility of irreversible and reversible structural changes was shown by means of a small‐angle x‐ray diffraction method.