Polymer Reclamation Process
Mechanical conversion of thermoplastic textile scrap, yarn waste, film trimmings and cut-edge selvedges into clean, uniform polymer pellets through melting, degassing, extrusion and pelletisation defines this recycling mechanism. Synthetic fibre manufacturers and textile recycling plants operate thermal re-granulation to transform clean factory polyester or polyamide offcuts into reusable secondary polymer chips for extrusion spinning. The process subjects fragmented synthetic waste to high temperatures within a screw extruder, forcing molten material through fine mesh filters to strip insoluble residues.
Degraded polymers suffer reductions in molecular weight and intrinsic viscosity during thermal processing. The process is inapplicable to thermoset resins, vulcanised rubbers or crosslinked natural fibres like cotton and wool.
Processing Sequence
Sorted post-industrial textile waste undergoes mechanical cutting, shredding and agglomeration to generate uniform flake feeds suitable for machine hoppers. Shredded materials enter single or twin-screw extruders where controlled barrel heating melts the synthetic polymer above its melting point, approximately two hundred and sixty degrees Celsius for polyethylene terephthalate. Vacuum degassing chambers withdraw moisture, trapped air and volatile chemical finishes from the molten mass to reduce hydrolytic degradation.
Melt pumps force the liquid polymer through fine screen changers to capture particulate contamination before die plates extrude the material into strands cooled by water baths and sliced into uniform pellets.
Viscosity Control
Polymer degradation during melting shortens molecular chains, reducing the intrinsic viscosity of the reclaimed resin. Melt processing in the presence of trace moisture triggers hydrolytic chain cleavage, requiring pre-drying systems that reduce water content below fifty parts per million. For high-tenacity yarn extrusion, re-granulated chips enter solid-state polycondensation reactors where elevated heat under high vacuum drives transesterification reactions, rebuilding polymer molecular weight and raising intrinsic viscosity back to target spinning parameters.
Material Constraint
Feedstock purity directly dictates the mechanical quality of the output polymer chips. Textile scraps containing elastane blends, pigment additives, crosslinked polyurethane coatings or flame-retardant chemistries char inside the extruder barrel, blinding melt screens and creating weak spots in re-spun synthetic yarns. Thermal re-granulation cannot process mixed fibre textiles without upstream mechanical separation or selective chemical stripping of non-thermoplastic elements.
