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Persistent Toughness and Heat Triggered Plasticization in Polylactide Modified with Poly(ethylene
Jonathan P Coote1, Matthew C Larson1, Frank S Bates1
1Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States.
ACS Macro Letters
|January 2, 2025
Summary
Adding poly(ethylene-oxide)-block-poly(butylene oxide) to poly(lactide) enhances toughness and accelerates degradation. This blend maintains durability for packaging and degrades faster when heated.
Area of Science:
- Polymer Science
- Materials Science
- Sustainable Materials
Background:
- Poly(lactide) (PLA) is a biodegradable polymer suitable for single-use packaging.
- PLA's applications are limited by brittleness and slow degradation under typical conditions.
- High glass transition temperature (Tg) of PLA restricts its biodegradability to industrial composting.
Purpose of the Study:
- To improve the toughness and biodegradability of poly(lactide).
- To investigate the effect of poly(ethylene-oxide)-block-poly(butylene oxide) (PEO-PBO) on PLA properties.
- To assess the long-term stability and end-of-life degradation of PEO-PBO/PLA blends.
Main Methods:
- Blending poly(lactide) with 5 wt% poly(ethylene-oxide)-block-poly(butylene oxide) (PEO-PBO).
- Assessing blend toughness and morphology over nine months.
- Investigating degradation kinetics after thermal annealing and exposure to elevated temperatures in artificial seawater.
Main Results:
- PEO-PBO addition significantly improved PLA toughness, maintaining it for over nine months.
- Oxidative degradation of PEO-PBO formed oligomers confined within PLA's glassy matrix.
- Thermal annealing induced PEO-PBO degradation product migration, plasticizing PLA and reducing Tg.
- Aged PEO-PBO/PLA blends degraded nearly twice as fast as neat PLA at 50 °C.
Conclusions:
- PEO-PBO acts as a dual-function additive, enhancing PLA toughness during use and accelerating degradation post-use.
- Heat-triggered plasticization of PLA by PEO-PBO degradation products facilitates faster biodegradation.
- This approach addresses key limitations of PLA for sustainable packaging applications.
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