For the last couple of decades, researchers have been trying to explore eco-friendly materials which would significantly reduce the dependency on synthetic fibers and their composites. Natural fiber-based composites possess several excellent properties. They are biodegradable, non-abrasive, low cost, and lower density, which led to the growing interest in using these materials in industrial applications. However, the properties of composite materials depend on the chemical treatment of the fiber, matrix combination, and fabrication process. This study gives a bibliographic review on bio-composites specially fabricated by the injection-molding method. Technical information of injection-molded natural fiber reinforcement-based composites, especially their type and compounding process prior to molding, are discussed. A wide variety of injection-molding machines was used by the researchers for the composite manufacturing. Injection-molded composites contain natural fiber, including hemp, jute, sisal, flax, abaca, rice husk, kenaf, bamboo, and some miscellaneous kinds of fibers, are considered in this study.

Modern industrial innovation demands smart materials capable of fulfilling multifaceted objectives.

Polymer composites have opened a novel innovation phase in additive manufacturing (AM), and now lightweight, high-strength, and geometrical advanced components with tailored functionalities can be produced. The present study introduces advances in polymer composite materials and their integration into AM processes, particularly in rapidly growing industries such as aerospace, automotive, biomedical, and electronics. The embedding of cutting-edge reinforcement materials, such as nanoparticles, carbon fibers, and natural fibers, into polymer matrices enhances mechanical, thermal, electrical, and multifunctional properties. These material developments are combined with advanced fabrication techniques, including multi-material printing, in situ curing, and functionally graded manufacturing, which achieves accurate regulation of microstructures and properties. Furthermore, high-impact innovations such as smart polymer composites with self-healing or stimuli-responsive behaviors, the growing shift toward sustainable, bio-based composite alternatives, are driving progress. Despite significant advances, challenges remain in interfacial bonding, printability, process repeatability, and long-term durability. This review offers a comprehensive overview of current advancements and outlines future directions in polymer composite–based AM.

Nanoparticles are widely used in biocomposite materials due to their ability to improve the mechanical properties of composites. This comprehensive review analyzes the use of nanoparticles to enhance the experimental low and high-velocity impact resistance of natural fiber composites. Various nanoparticles like carbon nanofibers, carbon nanotubes, boron nitride, zinc oxide, and titanium dioxide were investigated as reinforcements at different loading levels. The addition of nano-ZrO ₂ alone or with graphene oxide yielded the highest impact resistance and interlaminar shear strength of basalt fiber/epoxy composites. Cloisite 20A clay improved the mechanical properties of an epoxy matrix. Carbon/epoxy laminates showed improved maximum impact force, energy absorption, and displacement with 2wt% carbon nanofibers loading. Nanoparticles were found to enhance moisture and temperature resistance by strengthening the fiber–matrix interface. The literature demonstrated that small amounts of well-dispersed nanoparticles can meaningfully improve natural fiber composites’ impact resistance, strength, stiffness, toughness, and energy absorption through mechanisms like crack arresting and bridging. Hybrid carbon-basalt fibers and calcium carbonate nanoparticles also enhanced composite performance. Balancing the nanoparticle loading is crucial to prevent agglomeration effects. Future studies on their toxicity and environmental impacts would be needed for widespread commercial applications of Biocomposites.