STRESS-RELAXATION OF POLYESTER FIBER POLYURETHANE ELASTOMER COMPOSITEWITH DIFFERENT INTERFACIAL BONDING AGENTS

The stress relaxation behavior of polyurethane elastomer and short pol yester fiber filled elastomer composites with and without bonding agen ts at different strain levels and strain rates was studied. It was fou nd that these compounds exhibit a multistage relaxation mechanism and that the rate of relaxation and cross-over time depend on the strain l evel and strain rate. The incorporation of fibers reduced the stage-I relaxation rate and increased the cross-over time of the gum vulcanisa te. A higher rate of relaxation (first stage) was shown by the composi tes with longitudinal fiber orientation and composites with bonding ag ents.