Glossary of Terms Related to Chemical Recycling
1. Chemically Recycled Plastics
2.1 Depolymerisation
2.2 Pyrolysis
2.3 Gasification
2.4 Solvolysis
3.2 Dissolution
Definitions
1. Chemically Recycled Plastics
Plastics fully or partly produced from chemically recycled feedstock. The determination of recycled content can be done via feedstock attribution.
2. Chemical recycling
Chemical Recycling converts e. g. polymeric waste by changing its chemical structure to produce products (e. g. waxes) or substances (e.g., oil and gas) that are used as raw materials for the manufacturing of plastics or other products. Products exclude those used as fuels or means to generate energy. There are different chemical recycling technologies such as pyrolysis, solvolysis, gasification, hydro-cracking and depolymerisation.
Note: Alternatively, the terms “feedstock recycling” (synonym per ISO 15270: 2008) or “advanced recycling” (preferred in the American region) are used.
The below are chemical recycling processes...
2.1 Depolymerisation (or depolymerization)
Conversion of a polymer to its monomer(s) or to a polymer of lower relative molecular mass. The process can be mediated by e.g. heating, chemical solvents or enzymatic/catalytic reactions.
2.2 Pyrolysis
A thermal process of heating up polymeric waste (e.g., plastic) under the absence of oxygen. It converts polymers into a range of simpler hydrocarbon compounds mainly in the form of liquid pyrolysis oil.
Note: Pyrolysis is also used for cracking other substances/materials such as naphtha. The above definition is displaying the definition of pyrolysis of polymeric waste.
2.3 Gasification
A process where mixed after-use materials, such as polymeric waste, are heated in the presence of limited oxygen to produce primarily syngas that can be converted into polymers again.
2.4 Solvolysis
A process by which plastic waste is divided into its monomer components by means of different chemical solvents thus accordingly called glycolysis, methanolysis, hydrolysis, aminolysis.
3 Physical Recycling
Physical recycling refers to a number of different processes for recycling plastics that include mechanical recycling but also other physical treatments such as selective dissolution, extraction, precipitation and crystallization to purify the plastic without (intentionally) modifying its polymer chains chemically.
The below are physical recycling processes...
3.1 Mechanical Recycling
A method processing by which plastics is recovered from plastics wastes without intentionally changing the basic polymeric structure of the material. Plastic waste undergoes sorting processes in specialized sorting facilities to separate different plastic streams. After cleaning and grinding the sorted plastic waste, the material is recovered by melting and reshaping (e.g. regranulating) processes (pellets, flakes or powders), to be used in the manufacture of plastic parts and products.
3.2 Dissolution
A purification process through which the polymer present e. g. in a mixed plastics waste or in a multi-layer formulation/ composite is selectively dissolved in a solvent, allowing it to be separated from the waste and recovered in a pure form without changing its chemical nature. Note: The process belongs to physical recycling processes
4. Organic Recycling
Recycling (e.g. via composting or anaerobic digestion) of biodegradable/compostable organic waste including biodegradable/compostable plastics under controlled conditions using microorganisms to produce, in the presence of oxygen, stabilized organic residues, carbon dioxide and water or, in the absence of oxygen, stabilized organic residues, methane, carbon dioxide and water. The term “biological recycling” is used synonymously.
Note: Landfill shall not be considered a form of organic recycling
