Enzymatic Degradation of PLA: Preferential Degradation of the Amorphous Fraction
Bibliographic record
Abstract
Polylactic acid (PLA), a widely used biobased biopolymer, is highly resistant to biodegradation under ambient conditions, contributing to persistent plastic pollution and posing potential environmental and health risks. This study investigates the enzymatic degradation of PLA by Proteinase K, a proteolytic hydrolase enzyme with the ability to degrade PLA, and explores the underlying mechanisms for degradation. Both amorphous and semi-crystalline PLA were treated with Proteinase K (2 mg/mL) at 37 °C over varying time periods. PLA degradation was evaluated using multiple techniques, including weight loss measurement, pH reduction, quantification of lactic acid monomer release by High-Performance Liquid Chromatography (HPLC), surface morphology analysis through Scanning Electron Microscopy (SEM), changes in thermal properties by Differential Scanning Calorimetry (DSC), and structural changes by X-Ray Diffraction (XRD). The data revealed that the degradation of amorphous regions of the PLA polymer was faster and more extensive than the crystalline regions of the polymer. Repeated enzymatic treatments significantly enhanced the degradation rate. Furthermore, Proteinase K showed a clear preference for degrading amorphous regions of the PLA, as evidenced by higher weight loss, sharper pH decline, higher lactic acid production, and more pronounced surface disruptions, such as visible gaps between degraded oligomer structures.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".