| Abstract | The long-term thermal resistance of three polyisocyanurate (PIR) materials (PIR I, PIR II, and PIR III), extruded polystyrene (XPS), and medium density spray foam (MDSPF) were investigated using the accelerated aging procedures defined in slicing and scaling methods in CAN/ULC-ULC S770 and ASTM C1045 for the following effects.
1. The effect of conditioning temperature on the aging of closed-cell foams by evaluating the long-term thermal resistance (LTTR),
2. Temperature dependent R-value of closed-cell foams (TDRV).
3. Comparison of the TDRV measured as per ASTM C518 and calculated as per ASTM C1045 for 5 years-aged full thickness boards with that of the accelerated aged thin slices as per CAN/ULC-S770.
First, closed-cell insulations were tested following the methods in CAN/ULC-S770. In addition to conditioning at 23 °C, the thin slices were conditioned at -10 °C and 50 °C. The LTTR was calculated as per ULC-S770. The thermal conductivity was tested at multiple (10) mean temperatures in addition to the specified 24 °C mean temperature at the testing points. The TDRV of the accelerated aged samples (thin slices) was calculated as 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 24°C) by the accelerated testing shows biases towards the LTTR measured at 5 years. The biases range from -4.7 - 7.1%, 0.6 - 8.7%, and -0.9 - 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 show 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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