Fireproof phosphorylated kraft lignin/polyester based composites: Green material for rocket propellant thermal protection systems
Bibliographic record
Abstract
Presented study was aimed to investigate the influence of surface functionalization of the industrial kraft lignin (KL) on mechanical and thermal properties of high-performance and fireproof composites based on unsaturated polyester (UPe) resin. In order to improve flame retardant properties, surface of the KL was modified by phosphorylation method in two-step process. First, direct grafting of phosphorus chloride on KL phenolic hydroxyl groups was performed and phosphoric acid ester of KL was formed. In the second step, phosphor ester of KL was recovered by precipitation in cooled isopropyl alcohol and the final obtained product, phosphorylated industrial kraft lignin with methyl terminal groups (KLP) was obtained. KLP mass contents in UPe based composites varied from 0.5 wt.% to 5.0 wt.%. Structural characterization was done via Fourier Transform-Infrared Spectroscopy (FT-IR). The effects of KLP surface functionalization and KLP mass contents on the UPe tensile properties were studied. Tensile strength (σ), elongation (ε) and Young's modulus of elasticity (E) and Shore A (Sh A) hardness of the UPe/KLP composites were analyzed in relation to the structure of KLP modification. Tensile testing results showed an increase in σ of 31 % for UPe/KL sample with 1.0 wt.% KL particles compared to the bare UPe matrix. The origin and cause of fracture that occurred during uniaxial tensile testing were analyzed using stereo microscopy. The obtained composites were tested on fire retardant properties in accordance with the standard test method UL-94V, and composites with 5.0 wt.% loaded KLP achieved V-1 category.
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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".