Polyaniline fibers, films, and powders: X-ray studies of crystallinity and stress-induced preferred orientation

Powder (hk0) and four-circle X-ray diffractometry are used to study the effects of hot-stretching on films and fibers of the emeralidine base form of polyaniline (EB-II). It is shown definitively that hot-stretching induces nucleation of new crystalline material rather than growth and/or orientation of pre-existing crystallites. The diffuse scattering from amorphous EB-II is dominated by short-range interchain correlations and develops preferred orientation in response to stretching but with a broader mosaic than the crystalline phase. For the maximally-stretched samples, the crystal fractions was determined by accounting for the different mosaic distributions of crystalline and amorphous phases, correcting for the mass of N-methylphenazolinium plasticizer and ruling out any significant contribution from NMP diffuse scattering to the amorphous EB-II profiles. Films stretched to L/L[sub 0] = 4.25 contain no more than 4% crystalline material while fibers with L/L[sub 0] = 4.5 are 24--30% crystalline. These fractional crystallinity values are significantly small than found for EB-II powder (60%). More importantly, these results have implications for models of electric properties which invoke interchain interactions.