A long polymer chain (linked beads) sits in a heated reactor with
a depolymerization catalyst (small orange spheres). The catalyst
docks on a backbone bond and cleaves it, releasing a monomer unit
(green bead) that drifts free — repeated scission events shorten the
chain and pile up recovered monomer in the vessel. Heat provides the
activation energy for scission; more catalyst gives more active
sites cutting the chain at once.
rate of scission ∝ [catalyst] · exp(−Eₐ / RT)
Mₙ(t) = Mₙ(0) / (1 + k·t·[cat]) (random/end-chain scission, simplified)
conversion = bonds broken / bonds initial
- Temperature — raises the scission rate constant via the Arrhenius relationship; too high risks unwanted side reactions (charring), too low stalls the reaction.
- Catalyst loading — more active sites cut more backbone bonds per unit time, but with diminishing returns once the chain is saturated with catalyst.
- Reaction time — advances as the reaction runs; conversion climbs and chain length falls as more bonds are cut.
- Chain length / monomer yield — the two are linked: as the average chain shortens, the pool of recovered monomer (the feedstock you can repolymerize) grows.