Mixing Effect on Reinforcement of Short Ramie and Linen Fiber/Carboxylated Acrylonitrile-Butadiene Rubber Composites

Composites were prepared from carboxylated acrylonitrile-butadiene rubber (c-NBR) and short ramie and linen fibers without surface-treatment in a Banbury mixer. Mechanochemical effects in mixing on the reinforcement of the composites were investigated by measuring their mechanical properties. Under high shear forces during mixing, ramie fibers easily underwent fibrillation and uniformly dispersed in the matrix rubber. The behavior exerted a reinforcing effect on the composite, resulting in low elongation, high strength, and a high modulus of elasticity. On the other hand, in the case of linen fibers, the mixing in the Banbury mixer simply caused the cutting of fibers followed by fibrillation at both ends. These composites were therefore reinforced to a lesser extent. Composites reinforced with pre-fibrillated ramie and linen fibers were thus inferior to those fibrillated in the mixer. Use of ramie fibers resulted in the improvement in both the specific surface area and surface activity due to the basis of mechanochemical reaction during mixing, and consequently, the interaction between the fibrillated ramie fibers and matrix rubber occurred within the composite.