ABSTRACT

Orientation in polymeric items involves the preferential alignment of molecular segments at various levels. Individual chain segments in the noncrystalline regions may be chain extended and aligned, while nonlinear chain segments may follow a general directional trend. Within crystalline regions the c axes of the unit cells may be aligned with-or preferentially oriented toward-a common orientational axis. Fibrils may be formed which share a common crystalline axis, or lamellar crystallites may be stacked with their lateral planes preferentially arrayed normal to the overall orientation direction. The precise morphology of an oriented sample is a function of many factors, including the structure prior to deformation and the process by which orientation was achieved. The molecular alignment developed during orientation strongly influences the properties of the resulting products; higher levels of orientation magnify the anisotropic response to external influences.