Nylon is a human‐made material and has been applied in many industrial fields. This literature review explores the use of nylon in biomedical applications and discusses the properties and three‐dimensional (3D) printability of this material. Nylon is studied due to its versatility as an engineering plastic that can be easily transformed into fibers, films, and molded parts. Due to nylon's biocompatible nature, it has desirable chemical stability and tunable mechanical properties making this material and its derivatives widely used as sutures, catheters, dentures, and so on. However, the interactions between nylon and human body tissues have yet to be fully understood. Nevertheless, nylon is hybridized with different materials and used as skin dressings. In recent years, nylon composites have been actively researched in tissue engineering as an alternative to metallic implants with an appropriate bioactivity potential for bone growth. As nylon is supposed to be in contact with the tissue for a long time, hence researchers are developing antimicrobial strategies for the nylon materials to even promote their potential a step further. The 3D printing of nylon is currently confined to specific applications due to the printing technology's current limitations.

The massive plastic production worldwide leads to a global concern for the pollution made by the plastic wastes and the environmental issues associated with them. One of the best solutions is replacing the fossil-based plastics with bioplastics. Bioplastics such as polylactic acid (PLA) are biodegradable materials with less greenhouse gas (GHG) emissions. PLA is a biopolymer produced from natural resources with good mechanical and chemical properties, therefore, it is used widely in packaging, agriculture, and biomedical industries. PLA products mostly end up in landfills or composting. In this review paper, the existing life cycle assessments (LCA) for PLA were comprehensively reviewed and classified. According to the LCAs, the energy and materials used in the whole life cycle of PLA were reported. Finally, the GHG emissions of PLA in each stage of its life cycle, including feedstock acquisition and conversion, manufacturing of PLA products, the PLA applications, and the end of life (EoL) options, were described. The most energy-intensive stage in the life cycle of PLA is its conversion. By optimizing the conversion process of PLA, it is possible to make it a low-carbon material with less dependence on energy sources.

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Polyethylene (PE) is one the most used plastics worldwide for a wide range of applications due to its good mechanical and chemical resistance, low density, cost efficiency, ease of processability, non-reactivity, low toxicity, good electric insulation, and good functionality. However, its high flammability and rapid flame spread pose dangers for certain applications. Therefore, different flame-retardant (FR) additives are incorporated into PE to increase its flame retardancy. In this review article, research papers from the past 10 years on the flame retardancy of PE systems are comprehensively reviewed and classified based on the additive sources. The FR additives are classified in well-known FR families, including phosphorous, melamine, nitrogen, inorganic hydroxides, boron, and silicon. The mechanism of fire retardance in each family is pinpointed. In addition to the efficiency of each FR in increasing the flame retardancy, its impact on the mechanical properties of the PE system is also discussed. Most of the FRs can decrease the heat release rate (HRR) of the PE products and simultaneously maintains the mechanical properties in appropriate ratios. Based on the literature, inorganic hydroxide seems to be used more in PE systems compared to other families. Finally, the role of nanotechnology for more efficient FR-PE systems is discussed and recommendations are given on implementing strategies that could help incorporate flame retardancy in the circular economy model.

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