Textile Glossary

Depolymerization

Definition

Depolymerization is the chemical cleavage of a polymer into its constituent monomer units or low-molecular-weight fragments, and can be understood as the reverse reaction of polymerization. It is carried out by the targeted application of heat (thermolysis), water (hydrolysis), chemical reagents (e.g., alcohols in alcoholysis), or enzymes, and results in the breaking of covalent bonds along the polymer chain. The monomers or oligomers obtained can subsequently be used again for polymer production, making depolymerization a central step in the chemical recycling of plastics and man-made fibers.

Use in the textile industry

In the textile industry, depolymerization is gaining importance primarily in the chemical recycling of polyester (PET) and polyamide (PA): through hydrolytic or glycolytic processes, end-of-life textiles are broken down into their original monomers, which can then be used to produce new fiber grades. Unlike mechanical recycling, this process enables the recovery of fibers at near-original purity and also allows the processing of blended fabrics, provided that only one of the polymer components present is depolymerized. The use of depolymerization processes is becoming increasingly relevant due to growing requirements for closed material loops and recycled content quotas in the textile industry.

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Frequently asked question

In mechanical recycling, the textile material is physically shredded and processed into new fibers or yarns without chemically breaking down the polymer structure; fiber properties generally deteriorate with each recycling cycle. Depolymerization, by contrast, chemically breaks down the polymer to the monomer or oligomer level, so that the source material is recovered at defined purity and can be repolymerized, which theoretically allows unlimited recycling cycles without loss of quality. The chemical approach is more complex in terms of process engineering and more energy-intensive, but offers advantages when processing contaminated textiles or those containing dyes.

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