Natural Fibres—A Potential Bio-reinforcement in Polymers for Fibre Reinforced Plastic (FRP) Structures—An Overview

Nature is the master source where we can locate several candidate materials for ecofriendly products. Natural fibres, cellulose nanofibres, cellulose nanocrystals and organic nano-silica are some examples only. Natural fibres being highly cellulosic exhibit attractive properties which can be effectively utilized to prepare ecofriendly and cost effective products which can replace many synthetic plastics. Utilization of biofibres will result in decreased emission, less wear to the processing tools, improve agricultural based economy and create rural jobs. The properties of these biomaterials vary much depending on the species, age, climate etc. of the plant source. Hence the reproducibility of the properties is less than the synthetic systems. Even though by sorting and giving appropriate treatments, can produce more reproducible result. The properties of natural fibres are dependent on the chemical composition of fibres. More cellulosic fibres exhibit excellent mechanical properties due to their more crystalline structure. The drawbacks of natural fibres like hygroscopic nature, lower mechanical performance etc. can be alleviated by hybridizing the same with other suitable biofibres or synthetic fibres. The interface properties of the composites can be improved by giving appropriate chemical and physical modifications. Strain compatibility is an important parameter in selecting hybrid fibres for reinforcement. It is reported earlier from our laboratory that hybridizing oil palm fibre with glass fibre in reinforcing phenol formaldehyde polymer resulted in very high improvement in properties of the system. As India a big producer of rice and wheat, we have much straw and rice husk unutilized in the paddy field which causes great environmental problems now a days. Presently it is used as cattle feed and as boiler fuel. Straw can be effectively utilized for reinforcement in cement for better properties. Both straw and rice husk are rich in silica content. It is possible to isolate organic nanosilica from these agricultural byproducts effectively. It can find enormous applications as a bionanomaterial in several systems. It is found to have many advantages as they exhibit antibacterial properties, self-cleaning etc. The cellulosic natural fibres, wood etc. are good source for extracting cellulose nanofibres and nanocrystals. As they are cent percent cellulosic they will superior in reinforcing polymer matrices giving excellent barrier properties and thermal stability to the systems. The macro natural fibres, cellulose nanofibres and other bionanomaterials like nano-silica can find versatile applications as structural materials and in packaging industry.