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Introduction to Circular Economy and Recycling Plastics
Published in Rupinder Singh, Ranvijay Kumar, Additive Manufacturing for Plastic Recycling, 2022
Deepika Kathuria, Monika Bhattu
The chemical recycling strategy is an approach to achieve circular economy by reducing the raw material demand and negative environmental impacts (Salem et al., 2009). This recycling strategy involves either depolymerization of polymer or repurposing of waste. In the depolymerization technique, the polymer waste is depolymerize returning to their starting point under specified settings feedstocks that have been purified and then repolymerized in order to produce virgin-quality polymeric materials (Oliveux et al., 2015). The depolymerization can be chemolysis, thermal (pyrolysis), hydrolysis, glycolysis, or photodegradation. The schematic representation of depolymerisation of PET by chemolysis using methanol and water is given in Scheme 1.1. Methanolysis of PET gives dimethyl terephthalate (DMT) and ethylene glycol, whereas upon hydrolysis it gives terephthalic acid (TPA) (Han, 2019). As discussed previously, post-consumer PET can be recycled mechanically, however it often leads to the production of lower-quality product, whereas chemical recycling retains the quality of the product.
Mechanisms of Heterophase Polymerization
Published in Hugo Hernandez, Klaus Tauer, Heterophase Polymerization, 2021
Following the same line of thought, a depolymerization reaction is any reaction that results in a decrease in the chain length of a polymer, resulting in the appearance of smaller polymer chains in the system (including monomers). Depolymerization typically happens for chain polymerizations at elevated temperature, above the so-called ceiling temperature, which is determined when the Gibbs free energy change during polymerization (or depolymerization) becomes zero (ΔG = 0).
Microbial Recycling of ‘Sustainable’ Bioplastics A Rational Approach?
Published in Ederio Dino Bidoia, Renato Nallin Montagnolli, Biodegradation, Pollutants and Bioremediation Principles, 2021
Mansi Rastogi, Sheetal Barapatre
Enzymatic depolymerization is a rather new recycling approach that has several advantages, including low energy consumption, mild reaction conditions, and the possibility for stereo-specific biopolymer degradation, and enzymatic repolymerization of the resultant monomers (Ignatyev et al. 2014). Depolymerization of PLA and other polymers and reutilization of monomers for new plastic synthesis are attractive recycling options. Physical, thermal, and chemical depolymerization have been considered and sometimes implemented by industry.
An exhaustive experimental evaluation on the effects of using Jatropha biodiesel as an admixture in a DI diesel engine powered by waste plastic fuel
Published in International Journal of Sustainable Energy, 2023
Rajan Kumar, Manoj Kumar Mishra, Manish Kumar Roy
Plastics have become prevalent in both residential and industrial settings due to their affordability and adaptability (Sunaryo et al. 2021). This extensive usage has resulted in a rapid increase in plastic production and, consequently, a significant accumulation of plastic waste (Sunaryo et al. 2021). Researchers worldwide are now focusing on fuels derived from the depolymerisation of plastic waste. Fuel produced from recycled plastics exhibits numerous diesel-like properties, positioning it as a promising substitute for traditional diesel fuel (Karisathan Sundararajan and Ramachandran Bhagavathi 2016). Waste plastic fuel comprises 55% aromatic compounds, and it has been demonstrated that initiating an engine with pure waste plastic fuel generates a higher quantity of soot (Mani and Nagarajan 2009; Kumar, Mishra, and Roy 2022a, 2022b; Mani, Nagrajan, and Sampath 2010). Moreover, it has been suggested that waste plastic fuel enhances engine performance by reducing viscosity when combined with heavy oil (Mani and Nagarajan 2009).
End-of-waste life: Inventory of alternative end-of-use recirculation routes of bio-based plastics in the European Union context
Published in Critical Reviews in Environmental Science and Technology, 2019
Demetres Briassoulis, Anastasia Pikasi, Miltiadis Hiskakis
Chemical depolymerization (solvolysis or chemolysis), refers to the processes in which the polymer is broken down into the starting monomers or other chemicals (derivatives) that can be further used as raw materials (IPTS, 2013). The most common processes of chemical depolymerization are glycolysis, methanolysis, hydrolysis and ammonolysis depending on the chemical agent used to break down the polymer (Molero, Lucas, Romero, & Rodríguez, 2009; Alavi Nikje & Nikrah, 2007; Schneiderman et al., 2016). Typical depolymerization reactions such as alcoholysis, glycolysis and hydrolysis yield high conversion to their raw monomers (Cornell, 1995). Chemical depolymerization is mainly applicable to condensation polymers such as polyesters, polyamides etc. (IPTS, 2013).
Viscosity reduction of heavy crude oil by dilution with hydrocarbons obtained via chemical recycling of plastic wastes
Published in Petroleum Science and Technology, 2019
Gerardo Martínez Narro, Cuauhtémoc Pozos Vázquez, Martha Ofelia Mercado González
There are several practices associated with plastic waste handling such as recycling methods, incineration, and landfills that can reduce environmental impacts, in addition to reducing the exhaustion of non-renewable natural resources. Chemical recycling, also known as tertiary recycling, consists in the complete or partial depolymerization of plastic materials to obtain secondary compounds of lower molecular weight that can be used for several purposes. The low molar mass compounds obtained by this process can be used as feedstock for the petrochemical industry (Rudolph, Kiesel, and Aumnate 2017).