Elastomers based on cellulose fibers

To synthesize a new type of elastomer based on cellulose fiber, the introduction of intermolecular crosslinkage with formaldehyde, decrystallization or disorder with ZnCl2 swelling, and grafting with acrylate having a homopolymer second‐order transition temperature below room temperature were tried on the viscose rayon fiber. First, graft copolymerization with MA, EA, and BA was carried out in an aqueous emulsion system by the ceric ion method. It was found that the breaking elongation and elastic recovery of EA‐grafted fibers were remarkably superior to those of fibers grafted with the other monomers. Grafting with EA was carried out on formalized fibers with and without preswelling by concentrated ZnCl2 solution. The grafted fibers after formalization revealed typical rubber elastic behavior over several hundred per cent graft‐on. Breaking elongation was much increased by the swelling treatment after formalization. The crystallinity of the cellulose parts in the grafted fibers was decreased by the swelling pretreatment, being hardly changed by increasing the extent of grafting. The degree of orientation of the cellulose parts was decreased by increasing the extent of grafting, especially in the case of swelling before grafting. From these results it was concluded that the flexible graft parts correspond to soft segments and the rigid cellulose parts reinforced by crosslinkage correspond to hard segments, and that in this way elastomeric behaviors is developed.