Poly(ethylene terephthalate) fibers. 1. Crystal structure and morphology studies with full-pattern x-ray diffraction refinement

Full-pattern fiber X-ray diffraction refinement has been used to study the structure and morphology of the crystallites of three poly(ethylene terephthalate) fiber samples with different heat treatment history. Diffraction data over the whole two-dimensional space were collected with a four-circle diffractometer. An iterative Fourier filter method is developed to separate the crystalline diffraction from the background scattering. Both the structure and morphology are found to be dependent on the heat treatment. Some properties of the fibers can be explained by the difference in the crystal structure and morphology of crystallites.