ABSTRACT:To improve adhesion between fiber and matrix, natural rubber was reinforced with a special type of alkali-treated grass fiber (Cyperus Tegetum Rox b). The cure characteristics and mechanical properties of grass-fiberfilled natural rubber composites with different mesh sizes were studied with various fiber loadings. Increasing the amount of fibers resulted in the composites having reduced tensile strength but increased modulus. The better mechanical properties of the 400-mesh grass-fiber-filled natural rubber composite showed that the rubber/fiber interface was improved by the addition of resorcinol formaldehyde latex (RFL) as bonding agent for this particular formulation. The optimum cure time decreased with increases in fiber loading, but there was no appreciable change in scorch time. Although the optimum cure time of vulcanizates having RFL-treated fibers was higher than that of the other vulcanizates, it decreased with fiber loading in the presence of RFL as the bonding agent. But this value was lower than that of the rubber composite without RFL. Investigation of equilibrium swelling in a hydrocarbon solvent was also carried out.
Polyurethanes with PTMO soft segments and toluene diisocyanate diamide as urethane segment were studied. The toluene diisocyanate diamide urethane segment was monodisperse in length. The soft segment length was changed by extending PTMO with TDI units to a soft segment length varying from 2 250 to 6 500 g · mol−1. Studied were the structure, the morphology, the thermal and thermal mechanical behavior, the elastic behavior, and the tensile properties. The monodisperse diisocyanate diamide urethane segments had a high crystallinity and the crystallites showed a curved nano‐ribbon morphology. Extending the PTMO units with TDI groups increased Tg and Tm of PTMO slightly, and the elastic properties at room temperature were not affected.magnified image
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