EFFECTS OF DISORDER ON FIBER DIFFRACTION PATTERNS

Diffraction patterns from oriented polycrystalline specimens of fibrous polymers sometimes contain features indicating that the constituent microcrystallites are disordered. Such disorder affects the relationship between the crystal structure and the diffracted intensities. Therefore, the effects of disorder must be considered when determining structures from fibre diffraction data. Theory is developed here that describes the intensities diffracted by disordered polycrystalline fibres, and is used to calculate diffraction patterns from simulated specimens with various kinds of disorder. The results show how Bragg and continuous diffraction are distributed on such diffraction patterns, and implications for structure determination are discussed.