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Open Access Article
1 - A Review of Mechanical Recycling of Polylactic Acid: Challenges and Recent Achievements
Farzane TabatabaeeThe growing use of polylactic acid (PLA) encourages technologists to conduct extensive research into valorization of PLA waste with best quality. In general, mechanical recycling of PLA is one of the most cost-effective recycling methods. However, recycled materials are MoreThe growing use of polylactic acid (PLA) encourages technologists to conduct extensive research into valorization of PLA waste with best quality. In general, mechanical recycling of PLA is one of the most cost-effective recycling methods. However, recycled materials are commonly used for minor applications due to the inherent thermo-mechanical degradation of the polymer during recycling, which mainly results in chain scissions and intramolecular and intermolecular transesterification reactions. Therefore, it has a negative effect on the molar mass distribution and consequently on the mechanical, thermal and rheological properties of recycled PLA. In this article, a review of recent research on the effects of mechanical recycling on the properties of PLA including structural, morphological, mechanical, rheological and thermal changes was done. Furthermore, a review of three main ways of valorization of recycled PLA including thermal modification, chemical modifications in the presence of stabilizers, chain extenders, branching agents and finally mixing with nanoadditives or with other polymers was done in order to improve the properties of recycled PLA. Moreover, due to the widespread use of natural fibers to improve the performance of PLA, the recyclability of natural fiber-reinforced PLA biocomposites was investigated. Finally, two important applications of recycled PLA in the food packaging and the 3D printing industries were discussed. Manuscript profile -
Open Access Article
2 - The effect of additives and masterbatch to improve the properties of recycled polyolefins
Hamidreza Haydari marziyeh hosseiniAlthough the recycling of polymer products is beneficial for the environment and economy, the main goal is to achieve the efficiency of raw (intact) polymers in recycled polymers. The best type of recycling to have maximum energy efficiency and minimum environmental con MoreAlthough the recycling of polymer products is beneficial for the environment and economy, the main goal is to achieve the efficiency of raw (intact) polymers in recycled polymers. The best type of recycling to have maximum energy efficiency and minimum environmental consequences is mechanical recycling. However, there are a number of differences between virgin and recycled polymers. Due to the structural changes and the presence of impurities in the polymer, it is difficult to achieve a quality recycling. Whether the recycled polymer is suitable for obtaining new applications or not is measured by mechanical tests (such as tensile test, impact test), physical tests (such as hydraulic stability, surface roughness) and operational tests (extrusion and molding) under standard conditions. When these tests are performed, most recycled polymers do not meet the requirements required for various applications, unless we use additives that improve their properties. These additives may include coupling agents, impact improvers, metal deactivators, melt flow regulators, antioxidants, masterbatches, etc., and each is used in some way to improve specific properties of the polymers. Although the recycling of polymer products is beneficial for the environment and economy, the main goal is to achieve the efficiency of raw (intact) polymers in recycled polymers. Manuscript profile
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