Progress in plant fiber-reinforced bio-based polyurethane composites

A kind of bio-based polyurethane composite was prepared by adding plant fiber into bio-based polyurethane that was synthesized from diisocyanate and bio-polyol component derived from lignocellulose or vegetable oil. This bio-based composite presents good mechanical properties. In the composite, hydrophilic plant fiber shows poor compatibility with the hydrophobic polymer matrix which can be improved by the surface modification of plant fiber. Alkali treatment removes parts of hemicellulose, lignin, wax and other components from the fiber surface, resulting in better mechanical interlocking between the fiber and matrix and the interfacial adhesion is enhanced. Both the fiber morphology and fiber content have significant impacts on the dispersion of fiber in the matrix. Long fibers are liable to be tangled when mixed with other materials, leading to stress concentration in the composite. Granular fiber with smaller particle size favors interfacial combination. Too high fiber loading leads to its insufficient wetting by the matrix, which promotes the agglomeration of fibers. The hydrophilic plant fiber is responsible for the composite's moisture absorption and the biodegradation in humid conditions. ©, 2015, Chengdu University of Science and Technology. All right reserved.