Polymer Depolymerization
A chemical recycling process breaks down synthetic polymers into their starting monomers using a reactive solvent. In polyester and nylon recycling, solvolysis uses solvents like water, methanol or glycols at high temperatures to cleave the polymer chains. This method allows the separation of synthetic fibres from blended textile waste.
The resulting monomers can be repolymerized into virgin-quality polyester.
Solvent Variations
The choice of solvent determines the specific chemical reaction, such as glycolysis, hydrolysis or methanolysis. For example, glycolysis uses ethylene glycol to break down polyethylene terephthalate, yielding bis(2-hydroxyethyl) terephthalate. This solvolysis method is highly efficient for clean polyester waste streams.
Choosing the right solvent depends on the composition of the textile input. Each reaction has different energy requirements.
Contaminant Removal
Textile waste often contains dyes, finishes and elastane, which can interfere with the chemical reaction. The solvolysis process must include pre-treatment or post-reaction filtration stages to remove these non-polyester materials. This purification step ensures that the recovered monomers are pure enough to spin into high-performance yarns.
This chemical cleaning is a primary advantage over mechanical recycling, which cannot remove bound colorants.
Industrial Scaling
High equipment costs and energy intensity are the primary challenges when scaling these chemical processes. Large-scale reactors require continuous solvent recovery systems to remain economically viable.
