Meaning
Thermoplastic resin processed from post-consumer or post-industrial waste streams undergoes mechanical or chemical reclamation to serve as a secondary raw material. Recycled plastic replaces virgin feedstock in manufacturing applications where contamination levels remain within tolerance for physical integrity. Material properties undergo changes during the reprocessing cycle, necessitating verification of melt flow index and tensile strength against virgin benchmarks.
Sourcing Economics
Polymer supply chains source feedstock from municipal collection streams or industrial manufacturing scrap which influences the resulting melt purity. High levels of cross-contamination from adhesives, labels, or mixed resin types increase the cost of purification stages during extrusion. Sorting precision determines the viability of the output for high-specification injection moulding tasks.
Moulding Performance
Processing variables require adjustment because heat history degrades polymer chain lengths during initial melt cycles. Rheological shifts affect the shrinkage rate and cycle time during the injection phase, potentially causing dimensional drift in finished parts. Manufacturers maintain stable outputs by blending secondary granules with virgin pellets to compensate for reduced molecular weight and impact resistance.
Tolerance Limits
Datasheets for secondary grades define wider ranges for thermal stability and mechanical performance than virgin material specifications. Part design needs to accommodate variations in viscosity that occur when batches originate from different recovery streams. Production systems relying on consistent pressure-to-fill ratios require tighter control over batch consistency to prevent short shots or flash.
