Effect of fiber morphology on rheological properties of plant fiber reinforced poly(butylene succinate) composites

Sisal fibers (SFs), steam exploded sisal fibers (SESFs) and steam exploded bagasse fibers (SEBFs) which have different fiber morphologies, were mixed with poly(butylene succinate) (PBS) using a torque rheometer. The rheological properties of these plant fiber-reinforced PBS composites were evaluated. Results show that the fiber morphology has a large effect on rheological behavior. At the same fiber content (e.g., 10 wt% and 30 wt%), the non-Newtonian index n of composites reinforced by flexible fibers with a higher aspect ratio and larger contact area with the matrix is smaller. In general, n decreases with increasing fiber content but when the fiber content is too high (e.g., 50 wt%), the aggregation of fibers is too extensive so that the actual contact area between fibers and matrix becomes much lower, n increase instead. At the same fiber content (e.g., 10 wt% and 30 wt%), the consistency indices of fibrous filler-reinforced composites are larger than those of powder-filled composites; the larger the actual contact area between the matrix and the fibers, the greater the consistency index of the composite.