Small Strain-Induced Abrupt Drop in the Electrical Breakdown Strength of Polypropylene Insulation
Bibliographic record
Abstract
It is commonly acknowledged that the electrical properties of polymer dielectrics remain stable before yielding. However, in this Letter, an abrupt 17.4% decline in the electrical breakdown strength was observed at 4% tensile strain in polypropylene (PP) insulation, which is far below its yielding strain (ε y, 16%). In situ scanning electron microscopy was conducted, and microvoids were unexpectedly found, forming at 4% strain, which is inconsistent with the understanding that cavitation only happens near ε y . The microvoids lead to higher free volume, increased carrier mobility, and the abrupt decline in the breakdown strength. Furthermore, such critical strain was identified as the elastic limit strain (ε e, 3.5%). On that basis, PP samples with suppressed yields and higher ε e (5.4%) were prepared with more elastomers. Only a 5.1% decrease in the breakdown strength was observed at 6% strain. This work reveals that suppressing yield and increasing ε e can improve the electrical performance stability of semicrystalline dielectrics under mechanical stress.
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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 | 0.001 |
| 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".