PLA Sheet Degradation After 24 Months in Four Environments

Core Principle

PLA degradation relies on two mandatory steps: thermal hydrolysis above 55°C to break long polymer chains, by mineralization via thermophilic microbes. Without sustained high temperature, PLA barely degrades under normal temperature.

1.Industrial Compost

Condition: Constant 55–60℃, high humidity, sufficient oxygen, thermophilic bacteria (compliant with EN13432 & ASTM D6400)

Status after 24 months: Fully mineralized, no visible fragments, zero microplastic residue. All PLA converted into CO₂, water and humus within 6 months.

Degradation rate: Over 99%

Risk: No environmental pollution

2.Home Compost

Well managed enclosed home compost

Condition: Fluctuating temperature & humidity, poor oxygen supply

Status after 24 months: No intact PLA sheet left; only trace invisible micron oligomer particles remain.

Degradation rate: 82%–94%

Risk: Very low soil pollution risk

Rough open-air home compost

Condition: Fluctuating temperature & humidity, poor oxygen supply

Status after 24 months: Massive cracked PLA fragments visible, abundant microplastics generated.

Degradation rate: 40%–60%

Risk: Medium soil pollution risk

Natural Soil (Buried Farm/Forest Soil)

Condition: Seasonal temperature 10–28℃, no sustained high temperature

Status after 24 months: Entire PLA sheet can be dug out; only slight whitening & edge cracking, nearly no real degradation.

Degradation rate: 20%–35%

Risk: Long-term soil microplastic accumulation

 Seawater (Coastal Marine Environment)

Condition: 10–25℃, high salinity, lack of PLA-degrading microbes

Status after 24 months: Sheet remains intact with yellow discoloration & marine organism attachment; degradation almost suspended.

Degradation rate: Below 15%

Risk: High marine plastic pollution risk, same as traditional PP/PET plastic