5 - Maleated coupling agents for the surface treatment of natural fibers

Abstract

Natural fibers, as potential replacement for man-made fibers in composite materials, have certain advantages, but their use is still a challenge. The main disadvantages in natural fiber/polymer composites are the poor compatibility between fiber and matrix and the relative high moisture sorption based on the difference in compatibility between hydrophobic nature of polymer and hydrophilic character of natural fibers. These drawbacks of natural fibers in composites limit the improvement in the mechanical properties of composites, as well as their application to a great extent. Surface treatments using chemical methods modify the fiber surface properties by improving adhesion between the fiber and the polymer matrix through a well-defined interphase whom physical and chemical properties determine the characteristics of the final material. Water sorption of natural fiber-reinforced composites is reduced and their mechanical properties are improved. Among different compounds known to promote adhesion by chemical treatments, maleated coupling agents, especially maleated polyolefins, have been quite effectively utilized to improve the compatibility between fibers and matrix and provide balanced properties for a more effective interlocking.