Enhancement of molecular weight reduction of natural rubber in triphasic CO <sub>2</sub> /toluene/H <sub>2</sub> O systems with hydrogen peroxide for preparation of biobased polyurethanes
Bibliographic record
Abstract
Abstract Molecular weight reduction of natural rubber (NR) with hydrogen peroxide (H 2 O 2 ) oxidizing agent is limited in biphasic water-toluene systems that is attributed to mass transfer. In this work, CO 2 was applied to the (aqueous H 2 O 2 )-(toluene-NR) systems with the objective of improving reaction efficiency. Experiments were performed on the reaction system with CO 2 at 12 MPa and at reaction temperatures and times of 60°C–80°C and 1 h–10 h to evaluate the reaction kinetics. CO 2 could enhance the NR molecular weight reduction by lowering the activation energy (from 121 kJ·mol −1 to 38 kJ·mol −1 ). The role of CO 2 in the reaction system seems to be the formation of oxidative peroxycarbonic acid intermediate and promotion of mass transport due to the reduction in the toluene-NR viscosity and interfacial tension. The epoxidized liquid NRs ( M ̅ n =4.9×10 3 g·mol −1 ) obtained from NR molecular weight reduction was further processed to prepare hydroxyl telechelic NR ( M ̅ n =1.0×10 3 g·mol −1 ) and biobased polyurethane.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.000 | 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".