Properties of Isoprene Rubber Reinforced with Treated Bleached Kraft Cellulosic Fibers or Rayon Fibers

Abstract Both native and regenerated (rayon) cellulosic fibers are potential reinforcing elements in rubbers due to their relatively good mechanical properties, suitable aspect ratio, low cost and low density. The properties of the cellulosic fibers can also be changed fairly easily by chemical treatment. The effects of two treatments, mercerization (NaOH-immersion) and benzylation, on the mechanical properties of a rubber-cellulose composite are here reported. The rubber matrix was isoprene and the fiber content 20% by volume (27% by weight). Mercerization of bleached kraft fibers gave a composite with a higher modulus and strength than was attained when untreated kraft fibers were used, whereas benzylation of both kraft fibers and rayon fibers caused a reduction in the strength and stiffness of the rubber composites. This is interpreted as being due to a decrease in the degree of interaction between the cellulose fiber and the matrix due to the benzylation. The effect of these treatments on the mechanic...