Influence of coupling agent on altering the reinforcing efficiency of natural fibre-incorporated polymers - A review

Natural fibre-reinforced polymer composites are increasingly replacing commercial composite materials. The limitations of conventional composites materials are overcome by green composites, which are easily available, more eco-friendly and less toxic. In the current scenario, green composites are emerging in the field of material science that involves improving their physical, mechanical and thermal properties. The poor interfacial adhesion and surface incompatibility between natural fibre and biodegradable polymers lead to reduced physico-mechanical properties. In order to overcome this issue, physical and chemical modification methodologies of the natural fibre and polymer matrix are employed, among which the addition of coupling agents has a critical contribution. This paper compiles several recent research works in the utilization of coupling agents such as silane, maleic anhydride, isocyanate, triazine, etc., with the various combinations of natural fibres and polymers. In addition to this, the extents of influence of coupling agents on the characteristics of the natural fibre reinforced composite materials are also reported. This gives an overview for the future researchers to identify the gap in the field of green composite materials and novel coupling agents for different natural fibre/polymer matrix combination.