Preparation and Characterization of Poly(lactic acid) with Different Molecular Weights by Thermal Hydrolysis
Bibliographic record
Abstract
A feasible and effective method of thermal hydrolysis to prepare poly (lactic acid) (PLA) oligomers with different controlled molecular weight from PLA is presented in this paper. The thermal hydrolytic reaction was carried out by immerging PLA resin pellets in boiling distilled water for a certain period of time. Ester groups in PLA chains are hydrolytically degraded in the presence of water and thermal, so PLA oligomers with different molecular weight were prepared. The structures and properties of PLA oligomers were characterized by FT-IR, GPC, DSC, etc. The results showed that thermal hydrolytic reaction could effectively reduce the molecular weight of PLA, which declines with the increase of the thermal hydrolytic reaction time. Meanwhile, the content of terminal hydroxyl group, glass transition temperature, melting point of PLA oligomers prepared from thermal hydrolytic reactions exhibit gradual changes with the extension of the thermal hydrolytic time.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".