Published online by Cambridge University Press: 16 September 2011
There are a large number of natural fibers that have the potential to replace synthetic fibers made from glass, carbon, and polymers as the reinforcing phase in composites. Interest in these fibers has increased, as they offer a sustainable, readily available, high specific modulus option. The high modulus of cellulose crystals makes them attractive as a reinforcing phase in composites. These cellulose crystals are the key structural component in natural fibers, but the complex microstructure of the fiber means that the full value of the cellulose crystal modulus cannot be utilized. Moreover, the surface of natural fibers can have varying chemistry depending on the pretreatment of the fiber and the degree to which lignin and other hydrophobic materials are removed from the fiber. In addition, cellulose swells in contact with water, and this can degrade the properties of the fiber and composite. A better understanding of the surface properties and techniques to control the composite interface are required if natural fibers are to fulfill their potential.