Effect of molecular structure on seal ability, flex crack and mechanical properties of linear low-density polyethylene films
Bibliographic record
Abstract
In this article, three linear low-density polyethylenes having different molecular structures were selected and films were produced from them using a semi-industrial cast film extrusion line. Rheological and gel permeation chromatography measurements were performed on the resins to assess their molecular structure. Mechanical, physical and sealability properties of the films were evaluated and the results were discussed with regard to the molecular structure of the resins. It was found that molecular weight and distribution of short-chain branching (comonomer) on the backbone of polyethylene chains are the main factors that control sealability, flexural cracking and mechanical properties. Placement of comonomer on medium length chains generated crystals with expanded unit cell that show lower melting peak. Sealing was controlled by crystal size distribution, chain diffusion and entanglement formation at the interface. linear low-density polyethylenes with lower melting point and boarder molecular weight distribution showed lower seal and hot tack initiation temperatures. Polydispersity along with molecular weight contributes to toughness and puncture resistance. Flexural cracking resistance was observed to be related to crystallinity, tie chain density and more importantly to the amorphous phase fraction. The amorphous part could absorb flexing energy and hinders crack initiation and propagation. Seal through contamination (caulkability) was found to be related to flowability and elasticity of the melt.
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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".