Chemical reactivity and supramolecular susceptibility of hardwood celluloses towards succinic anhydride
Bibliographic record
Abstract
In order to understand the chemical reactivity and the relative susceptibility of Iα and Iβ cellulose allomorphs of some tropical hardwoods with coupling agents bearing succinic moiety, their cellulose fibers were isolated and esterified by succinic anhydride molecule heated at 120 °C for 4 h in dimethylformamide(DMF)/pyridine(Py) used as swelling solvent. The morphological structure of Testulea gabonensis (T. gabonensis), Julbernardia pellegriniana (J. pellegriniana), Aucoumea klaineana (A. klaineana) and Tieghemella africana (T. africana) fibers were characterized by the MORFI® apparatus. The fibers were the longest for T. africana (769 μm), J. pellegriniana (717 μm) and T. gabonensis (700 μm) while those from A. klaineana were the shortest (624 μm). No difference was found between T. gabonensis, A. klaineana and T. africana fibers width which varied from 24.0 to 24.2 μm while J. pellegriniana cellulose exhibited the smallest width (18.6 μm). The cellulose fibers of T. gabonensis, T. africana and J. pellegriniana displayed the better reactivity as revealed by their respective weigh per cent gains: 16.57 ± 1.11%, 14.16 ± 0.67% and 12.96 ± 0.77% compared with A. klaineana (11.85 ± 0.62%). The latter exhibited the lowest decrease of crystallinity among those cellulose esters. Nevertheless, solid state 13C NMR showed a strong reactivity of amorphous cellulose and chains exposed on crystal surfaces than interior crystallite chains. Any evidence of Iα and Iβ allomorphs esterification was found in those cellulose fibers with the exception of T. africana which displayed a decrease of Iα and Iβ allomorphs without a preferential reactivity of Iα cellulose. The trend of heterogeneous phase esterification of cellulose fibers with succinic anhydride in DMF/Py at 120 °C for 4 hours to be merely controlled by amorphous phase and chains exposed on crystal surface was discussed.© 2017 International Formulae Group. All rights reserved.Keywords: Cellulose allomorphs, Esterification, Solid state NMR, X-ray diffraction
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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".