- Author
-
Gaddy, G. D.
|
Barbari, T. A.
|
Cullen, W. C.
|
Rossiter, W. J., Jr.
- Title
- Impact of Exposure Conditions on the Mechanical Properties of Polyisocyanurate Foam Insulations.
- Coporate
- Johns Hopkins Univ., Baltimore, MD
National Roofing Contractors Assoc., Rosemont, IL
National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- National Roofing Contractors Association. Problems: Issues and Answers. 10th Conference on Roofing Technology, Proceedings. April 22-23, 1993,
National Roofing Contractors Assoc., Rosemont, IL,
Gaithersburg, MD,
64-71 p.,
1993
- Keywords
-
polyisocyanurate foam
|
insulation
|
mechanical properties
|
blowing agents
|
building technology
|
field exposure
|
roofing
|
low-sloped roofs
|
temperature exposures
|
exposure time
- Abstract
- The effects of various exposure conditions on tensile modulus, tensile yield strength, compressive modulus, and compressive yield strength of polyisocyanurate foam roofing insulation materials were investigated. The three foams, CFC-11, HCFC-14lb, and CFC-11/CO₂ co-blown, tested in this study decreased in density, except the field-aged materials which did not change, with exposure time and no decrease in compressional modulus and compressional yield strength for laboratory exposure. The decreases in density were accounted for by the exchange of the less dense air for more dense blowing agent. The lack of decreases in the compressive properties may be due to a number of factors, including loss of the blowing agent which acts as a plasticizer when dissolved in the polymer and the completion of crosslinking reactions in the polymer. Some field exposed samples showed a decrease in compressional modulus which is attributed to the presence of blowing agent dissolved in the polymer. The extent to which each of these parameters contributes to the observed changes was beyond the scope of this study.