In this paper, a review of natural fibers composites used in protective armors for ballistic applications like bulletproof vests is presented. It seeks to compile the results and establish natural fiber composites as an alternative to absolute synthetic composites used for the same application. The review assesses the latest articles under two categories viz. only natural fibers and hybrid composites with natural and synthetic fibers. It covers a range of fibers from flax, basalt, curaua, kenaf, aramid, jute, coir, and hemp. The study systematically classifies the composites based on the ballistic limit they exhibit and the back face signature measured during standardized ballistic testing. In accordance with the results, the findings are compared against standard materials such as Kevlar used in ballistic armors. The hybrid composites are seen to present superior properties in comparison to plain natural fiber composites. Natural fibers provide an ecological and economical alternative to existing composites. The review shows promising results and immense future scope for natural fibers in the area of ballistic applications and they must be actively considered for replacing synthetic fibers in armor.

The present work aims to understand the effect of chemical treatment on the physical and mechanical characteristics of the natural fibers, namely, areca frond fibers, banana, and flax fibers. Chemical reagents viz. sodium bicarbonate, potassium permanganate, and chromium sulfate were used for surface modifications. Tensile strength of the fibers was determined for analyzing the influence of treatments. Scanning electron microscopy was adopted to visualize the surface morphology. Fourier transform infrared spectroscopy was performed on the fiber specimen to interpret functional group modifications. The research results indicated a decrease in fiber diameter with increase in density of fibers post treatments. For areca frond and flax fibers, chromium sulfate treatment was the most effective while that for banana fibers sodium bicarbonate based treatment turned out to be most effective over the others. Scanning electron microscopy images confirmed clear visibility of fiber inner cell structure, protruding secondary fibrils for treated fibers, reagent coating on the fiber surface was also observed in the case of chromium sulfate-treated samples. Fourier transform infrared spectroscopy analysis showed distinct bands indicating functional group modifications corresponding to cellulose, hemicellulose, and lignin.

The effect of resin modification through the incorporation of the biomass waste in the form of seashell powder on the mechanical properties of basalt fiber–reinforced epoxy/seashell composites is examined through experimental investigations. The resin modification is done through the addition of seashell powder in 5, 10, 15, and 20 wt.%. The modified resin is then reinforced with basalt fiber mat and the required laminate is obtained through compression molding technique. The specimens required for various mechanical tests, such as flexural, tensile, inter laminar shear (ILSS), and the impact strengths, are cut from the laminate as per the standard ASTM dimensions. The mechanical test results indicate that through the addition of the seashell filler additional toughening mechanisms are introduced which improves the strength of the composite laminate. The improvement in the flexural modulus value for all the laminates made from modified resin indicates the ability of the laminate to deflect the applied load effectively and efficiently. The optimum wt.% addition of seashell filler into the resin is found to be 5% for flexural, ILSS, and impact strength while for tensile strength it was observed to be 10%. The addition of higher wt.% loading of seashell filler into the resin has rendered the resin too thick and viscous with minimum flowability. Thus, there is a reduced wettability of the modified resin with the basalt fibers due to which the strength of the laminates reduces. The SEM analysis indicates widespread delamination for higher wt.% addition of the seashell filler into the resin.

Polymer matrix composites are one of the materials being extensively researched and are gaining a lot of importance due to advantages like high specific strength, greater flexibility in design, and reduced cost of manufacturing. In this study, tensile, flexural, impact, and interlaminar shear strength of chopped strand/plain weave E-glass composites were considered. Composite laminates with different stacking sequence were fabricated using Vacuum Assisted Resin Infusion Moulding (VARIM) technique. Fiber volume fractions (FVF) of 22%, 26%, and 30% were adopted. Experiments were conducted in accordance with ASTM standards. Results indicate that laminates with three layers of plain weave mat exhibited better tensile, flexural, and interlaminar shear strength. However, laminates with two layers of chopped strand mat and one layer of plain weave mat showed improved impact resistance. In addition, scanning electron microscopy was used to analyze the fracture surface. Polymer matrix composites are one of the materials being extensively researched and are gaining a lot of importance due to advantages like high specific strength, greater flexibility in design, and reduced cost of manufacturing. In this study, tensile, flexural, impact, and interlaminar shear strength of chopped strand/plain weave E-glass composites were considered. Composite laminates with different stacking sequence were fabricated using Vacuum Assisted Resin Infusion Moulding (VARIM) technique. Fiber volume fractions (FVF) of 22%, 26%, and 30% were adopted. Experiments were conducted in accordance with ASTM standards. Results indicate that laminates with three layers of plain weave mat exhibited better tensile, flexural, and interlaminar shear strength. However, laminates with two layers of chopped strand mat and one layer of plain weave mat showed improved impact resistance. In addition, scanning electron microscopy was used to analyze the fracture surface.