Mass Depletion
Quantitative differential values isolate the physical reduction between raw material inputs and usable polymer yields across thermal or chemical regeneration processes. During synthetic textile recycling, conversion loss accounts for the non-recoverable mass ejected as volatile off-gases, non-target oligomers, insoluble chars, filtered dyes and post-consumer contaminants. The metric establishes the conversion factor required to balance mass accounting books across polymerization reactors.
Chemical recycling lines must measure this shrinkage precisely at every processing step to avoid overstating certified yields.
Reaction Mechanism
Depolymerisation processes strip secondary additives from polyester or nylon waste streams through thermal breakdown or solvent dissolution. When polyethylene terephthalate undergoes chemical cleavage via methanolysis or glycolysis, non-polymer components such as elastane, moisture, sizing agents and titanium dioxide dulling agents separate into waste sludges, directly generating conversion loss. Higher contaminant loads in post-consumer garments increase mass shedding during early filtration passes.
Side reactions also convert target monomers into degraded degradation products that vacuum distillation systems strip out as purge streams. Extrusion operations monitor physical melt wastage alongside chemical breakdown yields, noting that mechanical degradation reduces the molecular weight of spinning pellets below operational filament draw thresholds.
Accounting Balance
Processing plants balance mass equations by deducting measurable process losses from initial intake weights before allocating certified green attributes to downstream products. A recycling facility that processes one thousand metric tons of mechanical fabric waste displaying an eighteen percent conversion loss can issue certificates for only eight hundred and twenty metric tons of recycled yarn. Independent certification bodies require documented reconciliation runs where furnace slag, filter cakes and aqueous wastes undergo formal weigh-scale verification against intake logs.
Inflating conversion efficiency overstates the recycled content assigned to commercial polyester lots, rendering trade claims legally non-compliant under global chain-of-custody protocols.
Contractual Tolerance
Standard conversion thresholds establish baseline expectations for raw synthetic waste yields. When feedstock contamination spikes, conversion loss escalates past contract boundaries, prompting contractual disputes over net usable resin volume. Buyers deduct raw material surcharges or demand price concessions when delivered bale quality forces unexpected mass loss during solvent recovery phases.
Technical datasheets define the acceptable processing loss ceiling across specific filament categories, grounding material procurement agreements in verifiable yield realities.
