Gas‐phase ethylene polymerization over polymer‐supported metallocene catalysts
Bibliographic record
Abstract
Abstract The activities of two (n‐BuCp)2ZrCl2 catalysts supported on methylaluminoxane (MAO)‐treated polymer particles were evaluated. The supports were spherical polymeric particles, containing macropores and prepared by suspension polymerization of 2‐hydroxyethyl methacrylate, divinyl benzene, ethyl styrene, and styrene. Both catalysts had a Zr content of 0.31 mass % and an Al/Zr ratio of 185; the supports for one of the catalysts contained 59 mass % 2‐hydroxyethyl methacrylate, whereas the support for the other catalyst had a 2‐hydroxyethyl methacrylate content of 10 mass %. Ethylene homo‐ and ethylene/1‐hexene copolymerization activities were determined for gas‐phase operation at temperatures of 50 to 90°C and ethylene pressures of ≈1.4 MPa. Polymerization activities were strong functions of temperature and 1‐hexene concentration; copolymerization activities of up to 23,200 kg PE/(mol Zr h−1) were obtained for 1‐h polymerization runs. The product particle morphology was excellent, mostly spherical particles essentially without fines. Scanning electron microscopy showed that the spherical copolymer particles, for all copolymerization conditions, consisted of well‐defined concentric spherical shells. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90:1319–1330, 2003
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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".