Chemical, biological, and nanoclay treatments for natural plant fiber-reinforced polymer composites: A review

Natural plant fiber-reinforced polymer composites have been in the limelight in the field of materials science for their mechanical properties, economy, and eco-friendliness. Properties of such novel composites depend on the adhesion and interaction between the fibers and the polymer matrix. Consequently, poor interaction can lead to declined mechanical properties, particularly strength. Surface modifications of fibers are carried out to enhance the bonding with the matrix by certain chemical treatments that remove hydroxyl groups in the amorphous cellulose region, making them hydrophobic and hence compatible with the matrix. Doing so also strengthens the composites, widening their scope of application. This review article provides comprehensive information about various surface modification techniques that include alkali, silane, acetylation, permanganate, peroxide, benzoylation, acrylation, acrylonitrile grafting, isocyanate, addition of maleated coupling agents, and fungal treatments. The working mechanisms and the effects of such treatments on mechanical strength are also elucidated. Furthermore, this review provides an overview of nanoclay inclusion in polymers, their addition techniques, and the augmentation of the mechanical properties of polymer matrix composites. The article concludes along with the field of applications, summary of pertinent challenges, and directions for future work.