Crystallinity development in polyacrylonitrile nascent fibers during coagulation

This paper has studied the crystal and thermal property of nascent fibers during the polyacrylonitrile coagulation process. A water (H₂O)/dimethyl sulphoxide (DMSO) mixture was used as the coagulation bath for the coagulation process of acrylonitrile(AN)/itaconic acid(IA) copolymer fibers in the study. By transforming the spinning conditions, especially air gap distance between the spinneret and coagulation bath, draw ratios, coagulation time, we received the crystal and thermal properties of nascent fibers under different conditions. The relationship between the property of nascent fibers and the spinning conditions has been studied by use of X-rays, SEM, differential scanning calorimetry (DSC) and so on. The results indicated that the degree of crystallization gradually increased with the rise of coagulation time and tended to a fixed value when reached some time. With the augment of draw ratios, the crystal degree appeared differently, in which it decreased when the air gap distance was 0 mm and it increased when the air gap distance was 1 mm and 2 mm. At the same time, the thermal properties showed little difference in peak position and biggish difference in heat energy, which indicated the ability to endure heat for latter spinning process and thermal stabilization process.