Specificity of lattice deformation in polyamidobenzimidazole

Angular displacement and intensity variation of a meridional X-ray reflection upon loading and unloading of oriented polyamidobenzimidazole fibres were measured at two temperatures (293 and 110 K). A number of anomalous features were observed in the dependence of the strain in extension, ε, on the stress σ and on temperature, among them the “lattice creep” (i.e., an increase of ε with time at constant σ) which has been tentatively attributed to conformational transitions in the macromolecular chains.