Foaming Polystyrene with Mixtures of Carbon Dioxide and HFC-134a
Bibliographic record
Abstract
Mixtures of blowing agents are becoming widely used in the industry either for economical reasons or for achieving better control of processing conditions. Despite the fact that they are commonly used for foaming, the literature is fairly scarce on that particular subject and the fundamentals are not very well understood. This work studies the effect of blending carbon dioxide and 1,1,1,2-tetrafluoroethane (HFC-134a) in polystyrene. Ultrasonic monitoring and online rheology provided information on the solubility and plasticizing effect of the gases. Results show that, on an equivalent molar basis, HFC-134a is slightly more soluble than CO 2 and is a more effective plasticizer. Moreover, HFC-134a generates foam samples with a higher nucleation density than CO 2 using similar processing conditions. Blending the two gases generates nucleate cell densities, which are intermediate to the pure gases but do not follow a log-additivity rule. It is hypothesized that blending gases affect their mutual diffusion coefficients, which in turn, largely dictates the final foam morphology.
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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) | 0.001 | 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".