Waste recycling is one of the key aspects in current day studies to boost the country’s circular economy. Recycling wood from construction and demolished structures and combining it with plastics forms wood-polymer composites (WPC) which have a very wide scope of usage. Such recycled composites have very low environmental impact in terms of abiotic potential, global warming potential, and greenhouse potential. Processing of WPCs can be easily done with predetermined strength values that correspond to its end application. Yet, the usage of conventional polymer composite manufacturing techniques such as injection molding and extrusion has very limited scope. Many rheological characterization techniques are being followed to evaluate the influence of formulation and process parameters over the quality of final WPCs. It will be very much interesting to carry out a review on the material formulation of WPCs and additives used. Manufacturing of wood composites can also be made by using bio-based adhesives such as lignin, tannin, and so on. Nuances in complete replacement of synthetic adhesives as bio-based adhesives are also discussed by various researchers which can be done only by complete understanding of formulating factors of bio-based adhesives. Wood composites play a significant role in many non-structural and structural applications such as construction, floorings, windows, and door panels. The current review focuses on the processing of WPCs along with additives such as wood flour and various properties of WPCs such as mechanical, structural, and morphological properties. Applications of wood-based composites in various sectors such as automotive, marine, defense, and structural applications are also highlighted in this review.

Increasing global environmental problems and awareness towards the utilization of eco-friendly resources enhanced the progress of research towards the development of next-generation biodegradable and environmentally friendly material. The development of natural-based composite material has led to various advantages such as a reduction in greenhouse gases and carbon footprints. In spite of the various advantages obtained from green materials, there are also a few disadvantages, such as poor interfacial compatibility between the polymer matrix and natural reinforcements and the high hydrophilicity of composites due to the reinforcement of hydrophilic natural fibers. This review focuses on various moisture-absorbing and sound-absorbing natural fiber polymer composites along with the synopsis of preparation methods of natural fiber polymer composites. It was stated in various studies that natural fibers are durable with a long life but their moisture absorption behavior depends on various factors. Such natural fibers possess different moisture absorption behavior rates and different moisture absorption behavior. The conversion of hydrophilic fibers into hydrophobic is deemed very important in improving the mechanical, thermal, and physical properties of the natural-fiber-reinforced polymer composites. One more physical property that requires the involvement of natural fibers in place of synthetic fibers is the sound absorption behavior. Various researchers have made experiments using natural-fiber-reinforced polymer composites as sound-absorbing materials. It was found from various studies that composites with higher thickness, porosity, and density behaved as better sound-absorbing materials.

Current work attempts to fabricate aluminium alloy AA2219 metal matrix composite (AMC) reinforced with natural bio-based sea shell powder (SSP) which is a ceramic material, in view of improving the mechanical and tribological properties. SSP was characterized by X-Ray Diffraction (XRD) to assess its chemical constituents and particle size. Stir casting route was adopted for fabricating AMCs reinforced with 1, 2 and 3 wt. % of SSP. Energy Dispersive X-ray Spectroscopy (EDS) was used to analyse the formation of secondary elements during casting and scanning electron microscopy (SEM) was used analyze the surface morphology of the composite specimen before and after tribological tests. Hardness, Compressive strength and tribological properties were evaluated using appropriate tests and corresponding ASTM standards. Characterization methods revealed that the formation of secondary elements was very low at 3 wt. % of SSP when compared with other compositions. Hardness and compressive strength was found to be maximum for 3 wt. % of SSP while the specific wear rate and coefficient of friction values were found to be lesser for the same composite when compared with the unreinforced alloy and were on par with the AA2219 composites containing synthetic reinforcements.

Innovations in additive manufacturing (AM) methods represent a significant advancement in manufacturing technology, opening new avenues for creating objects in various shapes and sizes. Fused deposition modeling (FDM) is a specialized AM technique in which computers build layers upon each other to form a complete 3D object. The feasibility of producing metal parts using these methods has been thoroughly analyzed, but the design process has yet to catch up with manufacturing capabilities. Biodegradable aliphatic polyester PLA is derived from lactic acid. To enhance its strength, PLA is combined with metal particles, resulting in versatile property improvements and applications. While the aesthetic and functional qualities of PLA–metal composite filaments are intriguing, they also present difficulties related to extrusion, equipment wear, and maintaining consistent print quality. These challenges could be mitigated, to some extent, with careful tuning and specialized hardware. However, the inferior mechanical properties of bioresorbable PLA filaments highlight the need for the development of infilled PLA filaments to improve strength and other characteristics. This review discusses the 3D printing of PLA infilled with metal particles, various materials used, and their properties as a matter of interest in AM technology. Additionally, the applications of PLA–metal composites, along with their implications, limitations, and prospects, are comprehensively examined in this article. This sets the stage for the development of high-strength, sustainable materials for use in a range of engineering and technology fields.

Composite materials are gaining attention owing to their exemplary characteristics and, if the materials are eco-friendly, they attract much more. One such composite of poly lactic acid (PLA) combined with bamboo fiber in the ratio of 80:20 is selected for this study. The composites are manufactured using additive manufacturing, or the 3D-printing technique. In this article, a novel approach of infilling a honeycomb with around 12 infill patterns has been made, and all the 3D-printed specimens were tested for their mechanical and tribological properties. The 3D-printed composites were characterized using Fourier Transform InfraRed spectroscopy (FTIR) and X-Ray Diffraction (XRD) to evaluate their chemical composition and crystallite size (CS), respectively. Based on the results, the cross infill pattern outperforms irregular geometries like the Gyroid in terms of impact strength owing to its efficient stress distribution and superior interlayer bonding. By utilizing bidirectional reinforcement and distributing loads uniformly, the grid infill was able to attain the Shore D maximum hardness due to its strong 3D lattice structure; the Octet infill is very resistant to wear, which improves energy absorption and decreases material loss. Such honeycomb-filled 3D-printed composites can act as high-mechanical-strength components and find their applications in aerospace applications like drones and their allied structures.

This study investigates the mechanical properties and optimization of hybrid composites composed of flax, vetiver, and mahogany fruit fillers (MFFs) using epoxy resin as the matrix material. Nine distinct composite configurations were fabricated using different MFF concentrations (0, 5, and 10 wt.%) to evaluate their influence on tensile strength, flexural strength, and impact resistance. The MFF was subjected to alkali treatment and characterized using FTIR, XRD, and particle size analysis to enhance its compatibility with the polymer matrix. Vetiver and flax fibers also underwent alkali treatment to improve interfacial bonding. The composite fabrication process followed the Taguchi L9 orthogonal array to optimize the design. Mechanical testing revealed that the incorporation of MFF significantly improved the overall performance, with FVM9 (10 wt.% MFF) exhibiting the highest tensile strength (56.32 MPa), flexural strength (89.65 MPa), and impact resistance (10.46 kJ/m²). The CRITIC–EDAS method was employed to rank the composite configurations, and FVM9 was identified as the optimal configuration. Comparisons with alternative MCDM methods (WASPAS, COPRAS, TOPSIS, and VIKOR) validated the reliability of the rankings, and FVM9 consistently performed the best. The sensitivity analysis demonstrated the robustness of the CRITIC–EDAS approach, as the rankings remained stable despite variations in the criterion weights. The synergistic effect of flax, vetiver, and MFF, along with improved interfacial bonding, contributed to the superior mechanical properties of the hybrid composites. These findings highlight the potential of FVM composites as sustainable, high-performance materials for various industrial applications in the automotive, construction, and aerospace sectors.