Femtosecond laser-induced porosity on poly(ethylene) surfaces—A crystallographic and rheological study
Bibliographic record
Abstract
In recent years, femtosecond (fs) laser irradiation of polymer surfaces has been shown to produce novel porous topologies that present a multi-scale roughness. In our study, grazing incidence x-ray diffractometry results showed the appearance of a monoclinic crystalline phase on fs laser machined high density polyethylene (HDPE) which is a deformation of the orthorhombic phase typically observed in pristine HDPE. This was accompanied by a local decrease in crystallinity. These findings confirmed that the induced porosity was a consequence of the rapid quenching of a superheated melt layer undergoing phase explosion. In addition, several poly(ethylene) samples with different average molecular weights were machined under the same conditions. Scanning electron micrography, along with small angle oscillatory shear tests, indicated that the final pore size decreases with increasing average molecular weight or increasing melt viscosity since these parameters act against bubble growth during phase explosion. In addition, through computed tomography, the internal structure of the porous layer was investigated. Through this technique, the average pore size and pore size distribution can be computed by chord length analysis. In conclusion, in this study, the mechanisms behind the formation of femtosecond laser-induced porous structures and the parameters that control their dimensions have been established.
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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".