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.
This investigation is carried out to understand the effects of water absorption on the mechanical properties of hybrid phenol formaldehyde (PF) composite fabricated with Areca Fine Fibres (AFFs) and Calotropis Gigantea Fibre (CGF). Hybrid CGF/AFF/PF composites were manufactured using the hand layup technique at varying weight percentages of fibre reinforcement (25, 35 and 45%). Hybrid composite having 35 wt.% showed better mechanical properties (tensile strength ca. 59 MPa, flexural strength ca. 73 MPa and impact strength 1.43 kJ/m2) under wet and dry conditions as compared to the other hybrid composites. In general, the inclusion of the fibres enhanced the mechanical properties of neat PF. Increase in the fibre content increased the water absorption, however, after 120 h of immersion, all the composites attained an equilibrium state.
13 January 2022 in Renewable and Sustainable Energy Reviews
This article is a short review of the circular material economy and recycling in the additive manufacturing (AM) of polymers. In the recent years, there has been a surge regarding the production of numerous products through AM of various polymers. AM can provide an opportunity for a better manufacturing solution to facilitate productivity and sustainability in the circular economy. AM with a circular economy approach can provide adequate incentives for the recycling and reuse of polymers. It is therefore crucial to analyse the possibilities of recycling and reuse of polymers in AM. Some ongoing research has attempted to remanufacture polymers from recycled materials. This is necessary because polymer waste is a critical threat to the environment making an effective end-of-life treatment imperative. This review aims to provide a holistic view of recycling and reuse of AM materials. Studies investigating remanufactured feedstock materials and polymers as well as composites have been reviewed. The findings point to the fact that there are significant opportunities for recyclable polymers to be used in the development of AM products.