Effects of Brominating Matrimid Polyimide on the Physical and Gas Transport Properties of Derived Carbon Membranes
Bibliographic record
Abstract
Bromination modification was initially carried out on Matrimid polyimide before undergoing carbonation to produce carbon membranes. Compared with unmodified Matrimid, brominated Matrimid shows lower chain flexibility, which is demonstrated by increased glass transition temperatures and molecular simulation results. Additionally, an increase in space between polymer chains was supported by fractional free volume (FFV) and d -spacing measurements. The improvement of chain rigidity of polyimide precursors serves to strengthen the membrane morphology during the production of carbon membranes. Thermal gravimetric analysis indicates that the thermal stability of polyimide decreases after bromination. The lower thermal stability and higher FFV value of brominated Matrimid result in higher gas permeability of carbon membranes pyrolyzed at a low pyrolysis temperature, while the selectivity remained competitive to those pyrolyzed from the original Matrimid precursor under the same conditions. However, the gas permeabilities of carbon membranes derived from modified Matrimid decrease significantly and become lower than those of carbon membranes from the original Matrimid, when the pyrolysis temperature is raised to 800 °C. This is due to the formation of more graphitic-like structure in carbon membranes from brominated polyimide, observed by the wide-angle X-ray diffraction. Therefore, it is concluded that bromination of Matrimid polyimide has significantly affected the pyrolysis behavior and the structure of the resulting carbon membranes. At a low pyrolysis temperature, carbon membranes derived from brominated precursors show attractive and superior gas separation performance.
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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 | 0.001 |
| 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".