Even though natural fiber reinforced polymer composites (NFRPCs) have been widely used in automotive and building industries, there is still a room to promote them to high-level structural applications such as primary structural component specifically for bullet proof and ballistic applications. The promising performance of Kevlar fabrics and aramid had widely implemented in numerous ballistic and bullet proof applications including for bullet proof helmets, vest, and other armor parts provides an acceptable range of protection to soldiers. However, disposal of used Kevlar products would affect the disruption of the ecosystem and pollutes the environment. Replacing the current Kevlar fabric and aramid in the protective equipment with natural fibers with enhanced kinetic energy absorption and dissipation has been significant effort to upgrade the ballistic performance of the composite structure with green and renewable resources. The vast availability, low cost and ease of manufacturing of natural fibers have grasped the attention of researchers around the globe in order to study them in heavy armory equipment and high durable products. The possibility in enhancement of natural fiber’s mechanical properties has led the extension of research studies toward the application of NFRPCs for structural and ballistic applications. Hence, this article established a state-of-the-art review on the influence of utilizing various natural fibers as an alternative material to Kevlar fabric for armor structure system. The article also focuses on the effect of layering and sequencing of natural fiber fabric in the composites to advance the current armor structure system.

A novel class of carbon nanotube (CNT)-based nanomaterials has been surging since 1991 due to their noticeable mechanical and electrical properties, as well as their good electron transport properties. This is evidence that the development of CNT-reinforced polymer composites could contribute in expanding many areas of use, from energy-related devices to structural components. As a promising material with a wide range of applications, their poor solubility in aqueous and organic solvents has hindered the utilizations of CNTs. The current state of research in CNTs—both single-wall carbon nanotubes (SWCNT) and multiwalled carbon nanotube (MWCNT)-reinforced polymer composites—was reviewed in the context of the presently employed covalent and non-covalent functionalization. As such, this overview intends to provide a critical assessment of a surging class of composite materials and unveil the successful development associated with CNT-incorporated polymer composites. The mechanisms related to the mechanical, thermal, and electrical performance of CNT-reinforced polymer composites is also discussed. It is vital to understand how the addition of CNTs in a polymer composite alters the microstructure at the micro- and nano-scale, as well as how these modifications influence overall structural behavior, not only in its as fabricated form but also its functionalization techniques. The technological superiority gained with CNT addition to polymer composites may be advantageous, but scientific values are here to be critically explored for reliable, sustainable, and structural reliability in different industrial needs.

Polylactic acid (PLA) is a thermoplastic polymer produced from lactic acid that has been chiefly utilized in biodegradable material and as a composite matrix material. PLA is a prominent biomaterial that is widely used to replace traditional petrochemical-based polymers in various applications owing environmental concerns. Green composites have gained greater attention as ecological consciousness has grown since they have the potential to be more appealing than conventional petroleum-based composites, which are toxic and nonbiodegradable. PLA-based composites with natural fiber have been extensively utilized in a variety of applications, from packaging to medicine, due to their biodegradable, recyclable, high mechanical strength, low toxicity, good barrier properties, friendly processing, and excellent characteristics. A summary of natural fibers, green composites, and PLA, along with their respective properties, classification, functionality, and different processing methods, are discussed to discover the natural fiber-reinforced PLA composite material development for a wide range of applications. This work also emphasizes the research and properties of PLA-based green composites, PLA blend composites, and PLA hybrid composites over the past few years. PLA’s potential as a strong material in engineering applications areas is addressed. This review also covers issues, challenges, opportunities, and perspectives in developing and characterizing PLA-based green composites.

In the field of hybrid natural fiber polymer composites, there has been a recent surge in research and innovation for structural applications. To expand the strengths and applications of this category of materials, significant effort was put into improving their mechanical properties. Hybridization is a designed technique for fiber-reinforced composite materials that involves combining two or more fibers of different groups within a single matrix to manipulate the desired properties. They may be made from a mix of natural and synthetic fibers, synthetic and synthetic fibers, or natural fiber and carbonaceous materials. Owing to their diverse properties, hybrid natural fiber composite materials are manufactured from a variety of materials, including rubber, elastomer, metal, ceramics, glasses, and plants, which come in composite, sandwich laminate, lattice, and segmented shapes. Hybrid composites have a wide range of uses, including in aerospace interiors, naval, civil building, industrial, and sporting goods. This study intends to provide a summary of the factors that contribute to natural fiber-reinforced polymer composites’ mechanical and structural failure as well as overview the details and developments that have been achieved with the composites.

Natural fiber such as bamboo fiber, oil palm empty fruit bunch (OPEFB) fiber, kenaf fiber, and sugar palm fiber-reinforced polymer composites are being increasingly developed for lightweight structures with high specific strength in the automotive, marine, aerospace, and construction industries with significant economic benefits, sustainability, and environmental benefits. The plant-based natural fibers are hydrophilic, which is incompatible with hydrophobic polymer matrices. This leads to a reduction of their interfacial bonding and to the poor thermal stability performance of the resulting fiber-reinforced polymer composite. Based on the literature, the effect of chemical treatment of natural fiber-reinforced polymer composites had significantly influenced the thermogravimetric analysis (TGA) together with the thermal stability performance of the composite structure. In this review, the effect of chemical treatments used on cellulose natural fiber-reinforced thermoplastic and thermosetting polymer composites has been reviewed. From the present review, the TGA data are useful as guidance in determining the purity and composition of the composites’ structures, drying, and the ignition temperatures of materials. Knowing the stability temperatures of compounds based on their weight, changes in the temperature dependence is another factor to consider regarding the effectiveness of chemical treatments for the purpose of synergizing the chemical bonding between the natural fiber with polymer matrix or with the synthetic fibers.

Sugar palm nanocrystalline celluloses (SPNCCs) were isolated from sugar palm fiber (SPF). In this study, acid hydrolysis (60 wt. %) at different reaction times (30, 45, and 60 min) was carried out to investigate the optimum yield of NCC. The physical properties, degree of polymerization, chemical composition, structural analysis, crystallinity, surface area and charge, zeta potential, thermal analysis, and morphological characterization were also conducted to determine the outcome (efficiency) of the process. The results showed that a needle-like shape was observed under transmission electron microscopy (TEM) studies. TEM analysis showed optimum aspect ratios of 13.46, 14.44, and 13.13 for isolated SPNCC-I, SPNCC-II, and SPNCC-III, respectively. From thermogravimetric analysis (TGA), the degradation temperature of NCC decreased slightly from 335.15℃ to 278.50℃ as the reaction time increased. A shorter hydrolysis time tended to produce SPNCC with higher thermal stability, as proven in thermal analysis by TGA. The optimal isolation time was found to be around 45 min at 1200 rpm during hydrolysis at 45℃ with 60% sulfuric acid. Therefore, the extracted SPNCC from SPF has huge potential to be utilized in the bionanocomposite field for the production of biopackaging, biomedical products, etc.

Over the last decade, the progressive application of natural fibres in polymer composites has had a major effect in alleviating environmental impacts. Recently, there is a growing interest in the development of green materials in a woven form by utilising natural fibres from lignocellulosic materials for many applications such as structural, non-structural composites, household utilities, automobile parts, aerospace components, flooring, and ballistic materials. Woven materials are one of the most promising materials for substituting or hybridising with synthetic polymeric materials in the production of natural fibre polymer composites (NFPCs). These woven materials are flexible, able to be tailored to the specific needs and have better mechanical properties due to their weaving structures. Seeing that the potential advantages of woven materials in the fabrication of NFPC, this paper presents a detailed review of studies related to woven materials. A variety of factors that influence the properties of the resultant woven NFRC such as yarn characteristics, fabric properties as well as manufacturing parameters were discussed. Past and current research efforts on the development of woven NFPCs from various polymer matrices including polypropylene, polylactic acid, epoxy and polyester and the properties of the resultant composites were also compiled. Last but not least, the applications, challenges, and prospects in the field also were highlighted.

The effects of carbon fibre hybridisation on the thermal properties of woven kenaf-reinforced epoxy composites were studied. Woven kenaf hybrid composites of different weave designs of plain and satin and fabric counts of 5×5 and 6×6 were manually prepared by a vacuum infusion technique. A composite made from 100% carbon fibre was served for a comparison purpose. Thermal properties of pure carbon fibre and hybrid composites were determined by using a thermogravimetric analyser (TGA) and differential scanning calorimeter (DSC). It was found that a hybrid composite with higher kenaf fibre content (fabric count 6×6) showed better thermal stability while the highest thermal stability was found in the pure carbon fibre composite. The TG and DTG results showed that the amount of residue decreased in the plain-designed hybrid composite compared to the satin-designed hybrid composite. The DSC data revealed that the presence of woven kenaf increased the decomposition temperature.