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首页> 美国政府科技报告 >Joint Industry/Government Research Project: Comparison of thermal aging for roof exposures and thin-specimens of experimental polyisocyanurate insulation foamed with alternative blowing agents.
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Joint Industry/Government Research Project: Comparison of thermal aging for roof exposures and thin-specimens of experimental polyisocyanurate insulation foamed with alternative blowing agents.

机译：联合工业/政府研究项目：屋顶暴露的热老化和用替代发泡剂发泡的实验性聚异氰脲酸酯绝缘薄样品的比较。

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This paper reports apparent thermal conductivity (k) values from field exposures and laboratory aging of a set of industry-produced, experimental polyisocyanurate (PIR) laminated boardstock foamed with hydrochlorofluorocarbons (HCFCs) as alternative to chlorofluorocarbons (CFCs). The k-values were determined from 0 to 50(degree)C using techniques that meet ASTM C 1114 (Thin Heater Apparatus) and ASTM C 518 (Heat Flow Meter Apparatus). The increase in k observed for field exposure in the ORNL Roof Thermal Research Apparatus (RTRA) was confirmed by independent laboratory tests. The observed laboratory increase in k was about the same, between 17 and 22%, for all three blowing agent foams for a 450 day field exposure in the RTRA. Thin specimens were planed from the industry-produced boardstock foams and aged at 24 and 65(degree)C for up to 460 days. The foams blown with alternative blowing agents exhibited long-term k-values 7 to 15% above those for CFC foams under similar conditions. Field exposures were conducted on specimens under single ply EPDM membranes in the RTRA for over 680 days. Hourly averages of panel temperature and heat flux were analyzed to obtain k as a function of mean insulation temperature on a week-by-week basis. The k-values derived from the field data provided effective diffusion coefficients for air in the foam, which were within 7% of those obtained from the thin-specimen aging procedure at 24%C except for one sample. The relative performance of test specimens of HCFC-141b under a black and under a white membrane is reported, and data suggest that differences are relatively small. 26 refs., 10 figs., 8 tabs.

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