Molecular Origin of the Anomalous Thermodynamic Behavior of Single-site Ethylene-1-octene Copolymer Liquids with Different Branch Contents
Bibliographic record
Abstract
Zero-pressure-weight-fraction Henry's constants ( ) and infinite-dilution-weight-fraction activity coefficients ( ) of selected aliphatic and aromatic solvents in a series of single-site ethylene-1-octene copolymers (ss-EOs) with different branch contents were measured using inverse gas chromatography over the temperature range from 170 to 230 °C. It was observed that measured of solvents with high volatility exhibited a minimum in the branch content range of 0−20 branches per 1000 backbone carbons but were independent of branch content over the range from 20 to 87, while that of solvents with low volatility was insensitive to branch content at all. The observed behavior became more pronounced for highly volatile solvents and propagated to solvents with medium volatility as temperature was increased. It was found that the observed minima are mainly attributed to the relatively more favorable interactions between the solvents and the copolymers with branch contents less than 20, as quantified by the measured . However, for the solvents with extremely low volatility, such favorable changes in in the low branch content region did not manifest themselves in the measured as these changes were completely masked by the low volatility of the solvents even at 230 °C. Molecular dynamics (MD) simulation results on comparable ss-EO models with branch contents from 0 to 90 suggested that the observed behavior may originate from changes in the free volume hole size distribution, not from changes in the specific free volume of the copolymer. In particular, the simulation results showed that regardless of the temperature, the volume fraction of spherical free volume holes with radii larger than 1.5 Å decreased as the branch content was increased, while the specific free volume stayed constant.
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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".