The use of lightweight natural fiber functional composites in the manufacturing of ballistic protective materials has garnered significant attention in recent years. This is due to their superior mechanical properties, cost-effectiveness, and environmental sustainability. Ballistic panels are constructed using multiple layers of diverse composites, which collectively exhibit excellent mechanical properties. These properties enable them to withstand strong impacts enhancing their capability for different applications in defense, military, and aerospace components. The primary focus of this review is to examine the different influential factors that govern the development of novel polymeric materials for current ballistic applications. It also explores various research approaches, such as experimental, analytical, numerical modeling, and empirical techniques. The review highlights both internal factors, such as material composition, and external factors, such as projectile parameters (e.g., nose angles, projectile shape, and projectile size). These factors are crucial for optimizing the robust ballistic performance of natural fiber-based polymer composites. In addition, various valuable insights to develop more effective and sustainable ballistic protective materials for applications in bulletproof helmets, defense, aerospace, and military sectors have also been elaborated. Consequently, the article presents a comprehensive review of the impact of utilizing various natural fibers as alternative materials to Kevlar for armor structures, offering a state-of-the-art perspective and challenges faced in full-scale implementation.

Due to rising environmental awareness and dwindling oil supplies, many efforts have been made to replace synthetic fibres with plant fibre reinforced composites (PFRC). The need to eliminate plastics from everyday life has resulted in the development of a diverse range of eco-friendly natural-based composites for the automotive, chemical, and food packaging industries. PFRC plays an important role in the production of lightweight and cost-effective products. The current study looked at how different proportions of SiC/Al₂O₃ filler affected the mechanical properties of a plant fibre-based ramie/jute epoxy hybrid composite. By reinforcing a constant ramie (20 wt.%) and jute (10 wt.%) fibre with different proportions of SiC (2 –10 wt.%) and Al₂O₃ (0 –8 wt.%), hybrid composites were created using traditional stirring and compression moulding methods. The hybrid composite with 8% SiC and 2% Al₂O₃ (sample D) has higher tensile, flexural, hardness, impact, and interlaminar shear strength than the other combinations. The functional group of a nanoparticle-filled hybrid composite was evaluated using Fourier Transfer infrared Spectroscopy. Furthermore, SEM confirmed the excellent bonding of the viable hybrid composite combination’s filler, fibre, and matrix. According to the findings, a nano filler content of 8% SiC and 2% Al₂O₃ can improve mechanical properties and serve as a viable reinforcement in hybrid polymer composites for major engineering applications.

Various environmental concerns motivate scientists and researchers to look out for unique new materials in science and technology. In order to address the demand for polymeric materials with partial biodegradability, the usage of lignocellulosic fibre in the polymer matrix has risen. Lignocellulosic fibres are a cheap, easily renewable resource that is readily available in all regions. Cellulosic plant fibres also have a plethora of possibilities for use in polymer reinforcement because of their properties. Many researchers put their effort into developing a natural polymer with better mechanical properties and thermal stability using nanotechnology and the use of natural polymers to make its composites with lignocellulosic fibres. This study provides a review of the biodegradable composite market, processing methods, matrix-reinforcement phases, morphology, and characteristic improvements. In addition, it provides a concise summary of the findings of significant research on natural fibre polymer composites (NFRCs) that have been published. Indeed, a noticeably brief discussion is provided on the significant issues faced during composite extraction as well as the challenges encountered during the machining. Recent developments in the study of lignocellulosic fibre composites or NFRCs have demonstrated their enormous potential as structural elements in vehicles, aerospace structures, buildings, ballistics, soundproofing, and other structures.

Developing a hybrid phenomenological model for predicting the sound absorption coefficient of a pineapple leaf fibre/waste tea leaf fibre/glass fibre/epoxy-based natural fibre-reinforced hybrid composites is the predominant topic of this article. Phenomenological models excel at extrapolating characteristic impedance and wave number whereas empirical models require fewer inputs but overlook wave propagation in pores. Existing models apply only to single-fibre-reinforced composites, necessitating the creation of a hybrid model for hybrid composites. The developed hybrid Zwikker–Kosten and Johnson–Champoux–Allard model shows good agreement with experimental data across the frequency range, with standard deviations of 0.001–0.029 and percent deviations of 1.11%–11.43%. The overall noise reduction coefficient between the model and experiments is 0.31 vs. 0.30, with a 3.33% deviation. Furthermore, the application of alkali treatment increased the surface roughness which in turn, enhanced the sound absorption capabilities of these composites. The increased fibre roughness also amplified friction between fibres and sound waves, resulting in higher sound absorption coefficients. In addition, X-ray diffraction, thermal stability (thermogravimetric analysis and differential scanning calorimetry), and scanning electron microscopy examinations were performed on the designated composition (5% by weight of pineapple leaf fibre and 25% by weight of waste tea leaf fibre) of the pineapple leaf fibre/waste tea leaf fibre/glass fibre/epoxy-based natural fibre-reinforced hybrid composite.

Ultra-high-performance fibre-reinforced concrete (UHPFRC) is a specialized type of concrete (to create a very dense matrix) that is used for both new construction and renovation projects in order to improve the lifespan of structures. Researchers analyse and evaluate only the microstructure, porosity, and fresh and hardened concrete properties of UHPFRC but limited their exploration on the reduction of the mechanical properties of UHPFRC due to the presence of metallic particles and micro-fractures that occur during the generation of hydrogen. Hence, the present study aims to eliminate the existing problem by hybridization approach (mixing of bio-nano-silica (nS) and polypropylene) with different percentages to further improve the strength properties of UHPFRC. The result showed that the compressive strength is increased by 15.5 compared to traditional concrete due to the filling ratio of nS in the pores of the concrete; in addition, the fibres surface and roughness also contributed to the strength enhancement.