There is a growing interest in the development of natural fiber-reinforced composites, most likely due to their wide availability, low cost, environment friendliness, and sustainability. The market size for natural fiber-reinforced composites is projected to reach $5.83 billion by 2019, with a compound annual growth rate of 12.3%. The composite materials reinforced with wood, cotton, jute, flax or other natural fibers fall under this category. Meanwhile, some major factors limiting the large scale production of natural fiber composites include the tendency of natural fiber to absorb water, degradation by microorganisms and sunlight and ultimately low strength and service life. This paper has focused to review the different natural fiber treatments used to reduce the moisture absorption and fiber degradation. The effect of these treatments on the mechanical properties of these composites has also been summarized.

In this study, six different woven samples were produced on air jet loom with two different weave designs (i.e. 3/1 twill and 1/1 plain), three different picking sequences (i.e. single pick insertion (SPI), double pick insertion (DPI) and three pick insertion (3PI)). All the woven samples were singed, desized, bleached and finished together at industrial scale, as a single lot. The effect of these factors on the wetting, wicking and air permeability (AP) of the fabric samples was analysed. It was revealed that the fabric weave design and picking sequence has statistically significant effect on fabric wetting time, water spreading speed and AP of the fabric. It was found that fabrics woven in twill weave design and with simultaneous 3PI give significantly better AP, shorter wetting time and better water spreading rate as compared to plain woven fabrics and those with double or SPI. It could be concluded that the thermophysiological comfort of woven fabrics may be significantly improved simply by selecting a suitable weave design and picking sequence.

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The natural fibre composites are potential alternative of glass fibre composites for structural applications, automobile and furniture industry, but these are susceptible to the bacterial attack. The current study aims to investigate the bio-functionality of composites using flax woven fabric reinforcement along with ZnO nanoparticles. The ZnO nanoparticles were synthesised by sol-gel method and added in different fractions to unsaturated polyester resin before impregnation of reinforcement. The composites were fabricated by vacuum bag moulding technique, and bioactivity was tested in terms of antibacterial activity (zone of inhibition). The ZnO nanoparticles imparted bioactivity to the composites even in the lowest amount (0.02% by weight). These bioactive composites will help to lower the risk for fibre degradation and enhance the service life of composite, by restricting the growth of bacteria.

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