Rheology and Processing of Molten Poly(methyl methacrylate) Resins
Why this work is in the frame
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Bibliographic record
Abstract
Abstract The rheological and processing behavior in capillary extrusion of several poly(methyl methacrylate) (PMMA) resins was studied. The rheological characterization included: (i) frequency sweep experiments at various temperatures and application of the time-temperature superposition to obtain the master curves from which the activation energy of flow was found to be independent of molecular weight, (ii) extensional measurements using the Sentmanat Extensional Rheometer (SER) where it was found that poly(methyl methacrylate) resins exhibit strain hardening effects only at high strain rates. The capillary extrusion experiments were performed for three poly(methyl methacrylate) resins using additives in order to identify suitable processing aids for PMMA resins. First it was found that poly(methyl methacrylate) polymers exhibit spiral/helical type of distortions at a critical shear stress value of about 0.35 ± 0.03 MPa, independent of temperature and molecular weight. “Traditional” processing aids used mainly in the extrusion of polyolefins and some other commercial polymers were found ineffective in eliminating instabilities in the case of poly(methyl methacrylate) processing. On the other hand, mixing of poly(methyl methacrylate) with a proprietary blend of synthetic resins and fatty glycerides with modified organic fatty acids, MoldWiz INT-35UDH, was able to reduce the extrusion pressure and postpone the onset of gross melt fracture to higher shear rates. Finally and most importantly, the addition of different polyethylenes (LLDPE, LDPE and HDPE) resulted into a significant pressure reduction along with significant postponement of gross melt fracture to higher shear rates.
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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 it