EFFECT OF SWELLING ON THE STRUCTURE OF ORIENTED POLYAMIDE-6

The effect of swelling on the structure of polyamide 6 fibres was studied by means of small-angle and wide-angle X-ray scattering. The wide-angle show that only the amorphous phase undergoes swelling. Changes in the scattering contrast caused by such preferential sorption are in agreement with the increased 'apparent density' of liquids in the amorphous phase. Due to the fact that the increase in the long period corresponds to the amount of the liquid sorbed, swelling is virtually one-dimensional. If there is an interfibrillar non-crystalling phase, its content is very low, or its structure is not accessible to molecules of the swelling agent. The elongation of intrafibrillar amorphous interlayers due to swelling is reflected in changes in the small-angle four-point diagram. The changes suggest that swelling causes narrowing of the distribution of distances between crystallites in fibrils, increases the angle between ceystalline layers and the fibre axis and reduce waviness of crystalline-amorphous interfaces.