Biodegradable Plastics: Degradation Kinetics

Polymer

Environment

Temperature 25 °C

Enzyme / catalyst loading 0.0×

Simulation speed 2.0 days/s

Live Readout

Intact 100%Degraded 0%

Rate constant k

0.0000 /day

Half-life t₁/₂

—

Elapsed time

0.0 days

Fragments

How it works

Polymer breakdown (hydrolysis / enzymatic chain scission) is modelled as first-order kinetics: the fraction of intact material N(t) decays exponentially, and its rate constant k depends on temperature through the Arrhenius equation:

N(t) = N₀ · e^(−k·t)
k(T) = A · e^(−Eₐ / (R·T))
t₁/₂ = ln(2) / k

R = 8.314 J/(mol·K), T in kelvin, Eₐ = activation energy of the rate-limiting bond-breaking step. Each rendered particle is assigned its own random lifetime drawn from the exponential distribution with rate k — the same statistics that produce the smooth population curve N(t) from individually random molecular events.

Conventional (PE) — polyethylene's C–C backbone has a high activation energy (Eₐ ≈ 130 kJ/mol here); it degrades extremely slowly and its broken fragments persist as microplastic debris rather than mineralising.
Bioplastic (PLA) — polylactic acid's ester backbone hydrolyses more readily (Eₐ ≈ 95 kJ/mol); under composting-relevant heat its fragments continue breaking down and fade out, representing microbial mineralisation to CO₂ and H₂O.
Temperature — raising T increases k exponentially, exactly as in real composting facilities that run hot (50–60 °C) to accelerate bioplastic breakdown.
Enzyme / catalyst loading — represents added hydrolytic enzymes (e.g. PETase-type biocatalysts researched in green chemistry) that lower the effective activation energy, a real strategy for engineered plastic recycling.

Constants here are tuned for a demonstrable timescale (days, not years); the governing equations — first-order decay and Arrhenius temperature dependence — are the same ones used in real polymer-degradation and green-chemistry literature.

Intact polymer particle Degraded fragment

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