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Effects of Humidity and Elevated Temperature on the Density and Thermal Conductivity of a Rigid Polyisocyanurate Foam.


pdf icon Effects of Humidity and Elevated Temperature on the Density and Thermal Conductivity of a Rigid Polyisocyanurate Foam. (858 K)
Zarr, R. R.; Nguyen, T.

Society of the Plastics Industry (SPI). Polyurethanes 92. Annual Technical/Marketing Conference, 34th. October 21-24, 1992, New Orleans, LA, 422-430 pp, 1992.

Journal of Cellular Plastics, Vol. 30, 316-337, July 1994.

Keywords:

polyisocyanurate foam; rigid foams; humidity; temperature effects; density effects; thermal conductivity

Abstract:

Measurements of apparent thermal conductivity are presented for specimens of rigid polyisocyanurate (PIR) foam cut from a commercial insulation product and aged in air at 60 deg C and different humidities. Eight specimens, nominally 600 by 600 mm, were prepared from two boards (1.2 by 2.4 by 0.05 m) of rigid PIR foam blown with trichlorofluoromethane (CCl3F) and having permeable organic-inorganic facers. Facers and excess foam were removed by sanding the specimens to a thickness of 27.9 + 0.1 mm. Four specimens were placed in ambient conditions of 22 deg C and 40% relative humidity (RH). The remaining four specimens were each placed in one of the following environments: (1) 60 deg C and <10% RH; (2) 60 deg C and 40% RH; (3) 60 deg C and 60% RH; and, (4) 60 deg C and 75% RH. Measurements of apparent thermal conductivity were conducted at 24 deg C and a temperature difference of 22 deg C using a heat-flow-meter apparatus conforming to ASTM Test Method C 518. Measurements were conducted for a period of 357 days at approximately 50 day intervals. Aging curves of specimen mass, volume, density, and thermal conductivity for rigid PIR foam are presented and implications of changes in these properties are discussed in the paper. Supplemental measurements using Fourier transform infrared spectroscopy and scanning electron microscopy are also described in the paper.