The interfacial bonding can be achieved in several ways, including mechanical interlocking, electrostatic bonding, inter-diffusion bonding and chemical bonding . The latter is of particular importance since it delivers strong improvement of composite performance and such a strategy can be applied to the fiber or the matrix. The chemical approach includes treatments of alkali, acetyl, silane, benzyl, acryl, permanganate, peroxide, isocyanate, titanate, zirconate and acrylonitrile reactions plus maleated anhydride grafted coupling agent, but enzyme treatments are becoming more popular due to environmental concerns .