The supermolecular structure of viscose fibers and its dependence on spinning conditions
Annotatsiya
Abstract The supermolecular structure of viscose fibers (VF) has been studied by electron microscopy and some other physical methods. Experimental and industrial VF samples were selected at different spinning stages and served as the objects of investigation. Coagulation conditions (bath composition) were shown to affect significantly VF surface structure. Besides, the latter essentially depends on VF swelling and shrinkage in the course of spinning. In the case of tire cord fibers the surface reveals no significant changes after bath stretching; on the contrary, the structure of the surface and inner regions of the VF, spun according to the Lilienfeldt process (in concentrated sulfuric acid) shows noticeable changes after bath stretching. Electron micrographs of isotropic VF reveal a loose fibrillar network with pore dimensions and homogeneity depending on the coagulation bath composition and its component ratio (H 2 SO 4 /ZnSO 4 ). While increasing the ZnSO 4 content in the coagulation bath, some decrease of the network pore diameter was observed to take place. Stretching leads to the orientation of VF structural elements in the direction of the fiber axis, followed by formation of lamellar structures. Investigations of crystallites isolated by hydrolysis and estimation of their dimensions allow to come to conclusions on changes in the fine structure of microfibrils in the course of spinning. Electron microscopy data and some other VF structural characteristics are shown to be in good agreement.