On Variability in Physical Properties of Molded,Expanded Polystyrene

Abstract

When computer models are used for predicting field performance of moist insulation products, we must learn how to quantify the variability in measured properties. This is an issue of adequate material characterization. A description by the EPS type is not sufficient. By using additional elements of material characterization such as specimen density, one improves the precision of measurements of physical properties. In the case of thermal properties, a second element of material characterization, namely the coefficient describing attenuation of thermal radiation in the material (specific extinction coefficient) is also needed.

In effect, variation in thermal properties of EPS products is fully accounted for when defining only a few parameters such as bulk density, specific extinction coefficient, and thickness and temperature of the specimen.

Keywords

expanded polystyrene molded polystyrene EPS physical or mechanical properties material variability performance predictability thermal resistance thermal conductivity

Get full access to this article

View all access options for this article.

References

Ahlgren

, 1972, Moisture fixation in porous building materials (In Swedish), Rep 36, Lund Institute of Technology, Sweden, pp. 1–200.

Bartlet

P.A.

, 1985, Density and thermal gradients in billets and their effects on physical properties, Arco Chemical Company, presentation to annual meeting of EPS Division SPI Inc.

Bomberg

M.T.

Klarsfeld

, 1983, “Semi-empirical model of heat transfer in dry mineral fiber insulation,” J. Therm. Insul., Vol. 6, pp. 156–73.

Bomberg

M.T.

Kumaran

M.K.

, 1994, “Laboratory and roofing exposures of cellular plastic insulation to verify a model of aging,” Roofing Research and Standards Development, ASTM STP 1224,

Wallace

Thomas J.

Rossiter

Walter J.

Jr.

, Eds., American Society for Testing and Materials, Philadelphia.

Bomberg

M.T.

Swinton

M.C.

Kumaran

M.K.

Maref

, 2000, Long-term performance of exterior basement insulations, Submitted to International Building Physics Conference, IBPC 2000, Sept. 2000.

IEA-Annex 24, 1996, Task 3, material properties, prepared by M. K. Kumaran, Institute for Research in Construction, National Research Council Canada.

Kuhn

Ebert

H.P.

Arduni-Schuster

M.C.

Butner

Fricke

, 1992, “Thermal transport in polystyrene and polyurethane foam insulations,” Int. J. Mass Transfer, Vol. 35, No. 7, 1992, pp. 1795–1801.

Kumaran

M.K.

Stephenson

D.G.

, 1986, “Heat transport through thermal insulation: an application of the principles of thermodynamics of irreversible processes,” ASME, 1986, 86-WA/HT-70, pp 1–4.

Kumaran

M. K.

, 1998, An alternative procedure for the analysis of data from the cup method measurements for determination of water vapor transmission properties, J Testing and Evaluation, Vol. 26, No. 6, pp. 575–581.

10.

Plastifab Ltd, 1988, Presentation to annual meeting of the Expanded Polystyrene Association of Canada.

11.

Plastifab, 1989, Presentation to annual meeting of the Expanded Polystyrene Association of Canada.

12.

Sarlin

Jaervela

Toermaelae

, 1986, The inhomogeneity inside a block of expanded polystyrene (EPS), Plastics and Rubber Processing and Applications, Vol. 6, No. 1, pp. 43–49.

13.

Swinton

M.C.

Bomberg

M.T.

Kumaran

M.K.

Maref

, 1999, In-situ performance of expanded molded polystyrene in the Exterior Basement Insulation Systems (EIBS), Journal of Thermal Envelopes and Bldg. Science, Vol. 23, October, in press.

14.

Wieser Machinbau Gesellschaft News, 1998, Number 14.

15.

Zarr

R.R.

Davis

M.W.

Anderson

E. H.

, 1966, “Room temperature thermal conductivity of expanded polystyrene board for a standard reference material,” National Institute of Standards and Technology, Internal report, NISTIR 5838.