Improvement of Interfacial Adhesion in Natural Plant Fiber-reinforced Unsaturated Polyester Composites: A Critical Review

摘要

Natural plant fiber-reinforced unsaturated polyester (UPE) composites have lower strengths and absorb more water than glass fiber-UPE composites because of the incompatibility between hydrophilic natural fibers and hydrophobic UPE. The good interfacial adhesion between the natural fibers and the UPE matrix is essential for the superior mechanical properties and good water resistance for the natural fiber-UPE composites. Extensive work has been done on the improvement of the interfacial adhesion. This paper reviews various physical and chemical methods used in the treatments of natural fibers for the improvement of the interfacial adhesion. Physical methods include plasma and heat treatments of natural fibers. Chemical methods include alkaline treatments, acetylation, and benzoylation of natural fibers, the use of coupling agents, and in-situ polymerizations of acrylic acid, acrylonitrile, and styrene in the presence of natural fibers. Mechanisms by which these physical and chemical methods improve the interfacial adhesion between the natural fibers and the UPE matrix are discussed in detail. The effects of these methods on the improvements of mechanical properties and water resistance of the resulting natural fiber-UPE composites under the best conditions reported are also reviewed.