SERVICE LIFE DETERMINATION OF NITRILE O-RINGS IN HYDRAULIC FLUID
Bibliographic record
Abstract
ABSTRACT The service life of nitrile O-rings exposed to hydraulic fluid was determined by accelerated aging at nine temperatures and four immersion times. Tensile mechanical properties (elongation and low strain modulus), volume swell, compression set, and chemical crosslink density by solvent swell were measured. Calculated activation energies based on Arrhenius rate behavior ranged from 52 to 65 kJmol−1, approximately 20–30 kJmol−1 lower than nitrile rubber heat aged in air environments. Using a 50% loss of elongation as a failure criterion, an estimate of 15 yr of service life at 23 °C was calculated. This corresponds to a compression set of 50% and an increase of approximately 30% of the chemical crosslink density. Replacement of the plasticizer with the mineral oil and its additives increased total inorganic levels in degraded O-rings as measured by thermogravimetric analysis. Besides additional sulfur and sodium, energy dispersive spectroscopy identified the presence of phosphorous, chlorine, and potassium. Hydraulic oil additives are likely responsible in facilitating the O-ring degradation through lower energy pathways that accelerate nitrile rubber hardening.
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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".