Assessment of Polyethylene Geomembrane Properties after Accelerated Thermal Ageing
Bibliographic record
Abstract
Application temperatures and exposure environments are among the causes of premature antioxidant loss in polymer geomembranes. Therefore, over the long term, polymer degradation takes place which is reflected in geomembrane properties. In this work, accelerated thermal ageing of polyethylene geomembrane was carried out in a climatic chamber at 70℃ with 21% oxygen. The evolution of tensile properties, puncture resistance, and shore D hardness with exposure time was assessed. Changes in chemical and crystalline structure and melt flow index were made. According to the findings, geomembrane surface oxidation takes place in the polyethylene matrix after 9 months of exposure. This fact is confirmed by evaluating carbonyl, vinyl, and hydroxyl indexes. Uniaxial tensile properties, puncture resistance, and shore D hardness indicated slight changes after one year of exposure. While the crystallinity index, determined by XRD measurement, has shown an increase with exposure. Further, melt flow index measurements confirmed the absence of chain scission during the early exposure periods. However, for longer periods, chain scission reactions occurred and MI values increased moderately after five months of accelerated aging. All results indicated no significant bulk degradation while maintaining a certain mechanical resistance with applications under a temperature of 70℃. This temperature value is relevant in a waste storage center, but the studied geomembrane is not recommended for this case.
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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 | 0.000 | 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) | 0.001 | 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".