Mechanical Recycling Is an Economics Problem First
Most discussions of plastic recycling focus on collection and sorting. In practice,
the decision to recycle — and to recycle again — is made on a spreadsheet. If
reprocessing costs more than the value it recovers, material leaves the loop regardless
of how good the intent is. That is why process economics, not just technology, decide
whether polyolefins stay circular.
Where the Cost Hides
Mechanical recycling cost stacks up from sorting, washing, repelletising, and
compounding. A persistent hidden cost is property restoration: because every
reprocessing step degrades the chain, recyclers blend in virgin resin to recover
processability and performance. The more virgin needed, the thinner the margin — and
the weaker the environmental case.
Controlled Rheology Lowers the Virgin Penalty
Controlled rheology (CR) via organic peroxides attacks exactly this cost. Instead of
compensating for low, inconsistent MFI with virgin dilution, a recycler meters a
peroxide to set the MFI precisely where the next application needs it. The benefits
compound:
- Less virgin blend — the recyclate itself meets spec, so dilution drops.
- Higher throughput — a stable, predictable MFI runs faster with fewer rejects.
- Batch-to-batch consistency — fewer off-spec lots and less quarantine.
- Energy savings — visbreaking replaces energy-intensive re-extrusion passes.
A Simple Cost View
Consider a recyclate that, untreated, needs 30% virgin PP to reach an MFI of 12 g/10min
for injection moulding. Applying a CR peroxide grade lifts the recyclate to the same MFI
with only 10% virgin addition. At a virgin/PCR price gap that is meaningful at volume,
the peroxide cost is recovered many times over in avoided virgin resin — before counting
throughput and reject-rate gains. Lower virgin content also cuts the carbon footprint
per tonne of finished compound, strengthening both the P&L and the sustainability claim.
Designing Recycling for the Second and Third Loop
CR also makes multi-cycle recycling viable. Each loop can be re-rheologised to the
next application rather than discarded, stretching the usable life of the polymer and
the economics with it. Do Sender Chemicals supports this with peroxide grades whose
decomposition temperatures and residues are matched to typical recycling extruders,
so the treatment is robust on real, variable feedstock.
Conclusion
Advanced mechanical recycling is not a premium add-on; it is the condition for
recycling to pay. By putting controlled rheology at the centre of the reprocessing
step, peroxides turn recycled polyolefins into a reliably profitable, lower-carbon
feedstock — and that is what keeps the loop turning.