Effect of extensional viscosity on cocontinuity of immiscible polymer blends
Bibliographic record
Abstract
Cocontinuous blends were prepared from polyethylene (PE) and polylactic acid (PLA). The extensional and shear rheological properties of PE and PLA were independently tuned by varying long chain branching architecture. Shear rheological properties of the blend components were characterized by capillary and oscillatory rheometry. Extensional rheological properties were characterized by orifice entrance pressure drop and sheet wind-up. It was found that branching significantly increased zero-shear viscosity and extensional viscosity, but did not alter the shear viscosity at the shear rates typically observed in mixing flows. Adding a branched polymer to the blend allowed the other blend component to percolate into a continuous network with less material. Blending with two branched materials significantly broadened the range of cocontinuous compositions from 39–59 vol. % with a linear/linear blend to 25–76 vol. % for a branched/branched blend. This was attributed to the ability of a strain hardening matrix to promote elongation, and hence percolation, of the minor phase. Domain size was minimized when a slight amount of strain hardening was introduced, as this allowed formation of narrow features while stabilizing them against fiber breakup. All blends showed a rate of morphological coarsening during annealing inversely proportional to zero-shear rate viscosity, suggesting that quiescent coarsening flows are dictated by low-rate shear flow properties and not extensional properties. We find that our results and coarsening rates in the literature show the same linear dependence on the ratio of interfacial tension to log volume average zero-shear viscosity with a coefficient of ∼0.03, indicating a simple universal relation.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".