Effects of temperature on aging of closed-cell foam insulations and their temperature-dependent long-term thermal resistance
Bibliographic record
Abstract
The long-term thermal resistance (LTTR) of three polyisocyanurate (PIR) materials (PIR I, PIR II, and PIR III), extruded polystyrene (XPS), and medium-density spray polyurethane foam (MDSPF) was investigated using the accelerated-aging procedures of the slicing and scaling method as outlined in CAN/ULC S770 and ASTM C1045. The goal was to determine (1) the effect of conditioning temperature on the aging of closed-cell foams by evaluating their LTTR; (2) the temperature-dependent R-value (TDRV) of closed-cell foams; and (3) the difference between the TDRV measured per ASTM C518 and calculated per ASTM C1045 for 5-year-aged full-thickness boards and the TDRV of the accelerated-aged thin slices tested and calculated per ULC S770. First, closed-cell insulations were tested following the methods in ULC S770. In addition to conditioning at 23°C, the thin slices were conditioned at −10°C and 50°C. The LTTR was calculated per ULC S770. The thermal conductivity was tested at 1110 mean temperatures at the testing points in addition to the specified 24°C mean temperature. The TDRV of the accelerated-aged samples (thin slices) was calculated per ASTM C1045. Finally, the full-thickness boards were conditioned in the laboratory for 5 years at −10°C, 23°C, and 50°C. The TDRVs of the full-thickness boards were compared with those of the thin slices. The LTTR at the mean temperature of 24°C evaluated by the accelerated testing showed biases toward the LTTR at the mean temperature of 24°C measured at 5 years. The bias ranges were −4.7% to 7.1%, 0.6% to 8.7%, and −0.9% to 12.5% when the specimens were conditioned at −10°C, 23°C, and 50°C, respectively. The TDRVs of samples conditioned at 23°C and 50°C showed very close values for accelerated aging and 5-year laboratory aging. Regardless of the conditioning temperature, XPS aged similarly, reaching very similar TDRVs at 5 years and 5-year-equivalent periods.
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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 | 0.001 |
| 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".