Due to the dominating advantages of natural fibres such as biodegradability, eco-friendliness, nominal cost, low density and high specific strength, they are being used opposite to synthetic fibres in many industrial applications. Despite many advantages, these fibres face some limitations such as higher moisture uptake, quality variations, low thermal stability, and poor compatibility with polymeric matrix. To overcome these limitations, chemical treatments of these fibres were found to be the most suitable method to improve adhesion with polymers, increase their strength and water absorption resistance, and improve their composite properties also. Among chemical treatments, alkali treatment is the most widely used and versatile surface modification method of the natural fibres. A good number of research works have been carried out on effect of alkali treatment on the properties of natural fibres and its composites, which motivated for this review. In this paper, the effect of alkali treatment on the properties of natural fibres has been reviewed. In addition, the physical and mechanical properties, thermal analysis and tribological behaviour of its biocomposites are also reviewed. It was concluded that alkali treatment of natural fibres could provide enhanced properties of various bio-composites up to a great extent.
Nowadays, it has been global demand to overcome the abundant use of synthetic fibres with respect to save the environment. Sisal fibre is one of the widely used natural fibre and being used as reinforcement for polymer-based composites on account of its excellent properties. This review article deals a brief description of sisal fibre along with its recent applications and characterization of its polymer-based composites in terms of mechanical properties, thermal properties and tribological and water absorption behaviour. The recent applications of polymer-based sisal composites and recommendation for future work are also presented.
In view of environmental imbalance due to numerous use of manmade fibers and plastic products, demand of natural fibers reinforced biocomposites have been increased. The products prepare by these biocomposites have been used in the various applications. However, their utilizations are not found suitable in the applications where high strength and high water resistance are required. The prime aim of the present study is to improve the water resistance capacity and mechanical performance of aged sisal biocomposites. In this context, hand lay-up process was used to prepare the epoxy-based biocomposites by reinforcing the surface modified sisal fibers consisted of eco-friendly sodium bicarbonate treatment and poly (lactic acid) coating. The highest water absorption, thickness swelling, and sorption, diffusion and permeability coefficients of the fabricated sisal composites were studied. Moreover, the effect of water absorption on tensile, flexural, impact, and hardness properties of the sisal composites was also investigated. It was noticed that treated and coated sisal composite revealed the best water resistant behavior than all other the composites. This composite exhibited 30% lower water absorption capacity than that of pure sisal composite. Further, lowest degradation in mechanical properties, that is, tensile strength (3.59%), flexural strength (33.18%), and hardness (11.96%) was observed for treated and coated sisal composite.
K E Y W O R D Scoating, eco-friendly treatment, mechanical properties, thickness swelling, water absorption behavior
Recently, researchers and scientists are trying to overcome the environmental burden by using biocomposites in engineering applications as far as possible. The main source of biocomposites is cellulosic fibres which is a class of natural fibres. Instead of many advantages of cellulosic fibres, they and their polymer composites suffer from some limitations as well. The environmental conditions are one of the most important issues to degradation behavior of the cellulosic fibres polymer composites (CFPCs). Among the environmental conditions, water absorption is an important ground to degradation in the mechanical performance of the CFPCs, which resists them to be used in outdoor applications. Several studies have been presented on water absorption characteristics of cellulosic fibres and its polymer-based biocomposites. Further, the consequence of water uptake on the mechanical performance of biocomposites was also reported in many studies. In most of the cases, a negative effect of water absorption was observed, whereas in a few cases a positive effect was also seen. In the present study, mechanics and kinetics of water absorption for CFPCs are discussed. Further, a detailed literature review on water absorption of cellulosic fibres and their different types of polymer-based biocomposites has also been carried out. Furthermore, studies reported on the effect of water absorption on the mechanical properties were also systematically presented. Moreover, all the possible remedies to lower the water absorption capacity were also discussed in the present review paper.
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