The fine structure of fibers and crystalline polymers. II. The growth of crystalline regions in fibers

The ideas of spherulitic crystallization as found in bulk polymers are applied to crystal growth in a moving medium such as an extruded fiber. It is shown that the structure will depend on the velocity of motion and the crystalline growth and nucleation rates. If growth proceeds from a single nucleus a sector of a giant spherulite will form, growing at a front where the crystalline growth rate equals the velocity of motion but, if nucleation is predominant, then a structure of small spherulites or micelles will form. The effects of orientation and drawing are considered. A detailed mechanism of crystal formation in an oriented structure by means of a screw dislocation is discussed.