Meaning
Chain of custody accounting rules govern the explicit allocation of recycled or bio-based monomer inputs to specific downstream polymer production lots within integrated chemical plants. Petrochemical manufacturing sites apply monomer attribution to certify the bio-based or recycled content of polyolefins and engineering thermoplastics produced in shared reactor infrastructure. The framework tracks mass flow inputs from chemical recycling pyrolysis or bio-feedstock refining through polymerization.
It establishes commercial accounting credits and does not differentiate physical molecules in the final resin.
Allocation Protocol
Chemical cracking operations process circular naphtha alongside fossil feedstocks, outputting identical ethylene and propylene monomer streams. Through monomer attribution, plant operators assign verified recycled mass units directly to high-value polymer grades destined for regulated packaging applications. This credit transfer strategy allows chemical producers to market fully circular resins without building isolated monomer recovery loops.
Third party certification bodies audit chemical accounting ledgers to confirm that attributed monomer sales match verified circular feedstock receipts.
Mass Balance
Converting attribution credits into commercial resin datasheets enables brand owners to meet post-consumer recycled content targets. Relying on monomer attribution allows injection moulders to maintain identical processing parameters and mold shrinkage rates as virgin resin grades. Moulding facilities avoid processing problems like inconsistent melt flow rates and thermal degradation associated with mechanically recycled resins.
Audit Boundary
Mass balance attribution credits cannot exceed actual physical mass inputs entering the chemical cracker facility over a defined accounting period. Discrepancies in mass balance accounting lead to certification revocation and regulatory enforcement actions.
