Effects of Humidity and Elevated Temperature on the Density and Thermal Conductivity of a Rigid Polyisocyanurate Foam.
Effects of Humidity and Elevated Temperature on the
Density and Thermal Conductivity of a Rigid
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
polyisocyanurate foam; rigid foams; humidity;
temperature effects; density effects; thermal
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.