An Evaluation of the Thermal Conductivity of Extruded Polystyrene Foam Blown with HFC-134a or HCFC-142b

Abstract

Insulation performance of extruded polystyrene (XPS) foams expanded with various halogenated blowing agents including HFC-134a or HCFC-142b was measured over time. Residual blowing agents were measured after aging up to 26 years. The diffusive transport properties of the blowing agents can be determined through the mathematical calculation of the heat transfer in the gas phase component of the foam thermal conductivity. These values are used in a Dow model which allows an accurate prediction of the long-term thermal resistance of extruded polystyrene foams blown with a variety of blowing agents including CFC-12, HCFC-142b, HCFC-22, HFC-134a, HFC-152a, and CO₂. Excellent agreement was obtained between measured and predicted thermal conductivity values with samples stored in laboratory conditions, as well as samples extracted from field conditions, such as cellar and upside-down roof applications.

The results confirm the slow diffusion rate of CFC-12, HCFC-142b and HFC-134a through extruded polystyrene foam, and demonstrate that HFC-134a or HCFC-142b-blown extruded polystyrene (XPS) foams meet the requirement for applications requiring excellent long-term insulation performance. HCFC-22 and HFC-152a are fugitive blowing agents in XPS foams, and the thermal performance of foams made with these blowing agents reach the thermal performance of CO₂-blown foams after a short aging period.

References

1. Buttler, F. and Radlinsky, J. (May 17, 1979). The Change of Thermal Conductivity with Time of Extruded Polystyrene Skinboards , International Foamed Plastic Symposium.

2. Suh, K.W. and Paquet, A.N. (2003). In: Scheirs, J. and Priddy, D. (eds), Polystyrene Foams, Chap. 10. Modern Styrenic Polymers: Polystyrene and Related Polymers, John Wiley & Sons, Chichester, UK .

3. Suh, K. and Killingbeck, G. (1978). Styrene Polymer Foam and Preparation Thereof, Patent GB 1, 537–537, 421–421.

4. Gendron, R., Huneault, M., Tatibouet, J. and Vachon, C. (2002). Foam Extrusion of Polystyrene Blown with HFC-134a , Cellular Polymers, 21: 315–341 .

5. Dournel, P. and Zipfel, L. (2001). HFC Blends for the Production of High Performance XPS Insulating Foams , In: Blowing Agents and Foaming Process, Foams Conference 2001, Paper No. 24, pp. 1–7 .

6. Schuetz, M.A. and Glicksman, L.R. (March–April 1984). A Basic Study of Heat Transfer through Foam Insulation, J. Cell. Plastics, 114–121.

7. Reitz, D.W., Schuetz, M.A. and Glicksman, L.R. (March–April). A Basic Study of Aging of Foam Insulation, J. Cell. Plastics, 104–113.

8. Glicksman, L.R., Schuetz, M.A. and Sinofsky, M. (1987). Radiation Heat Transfer in Foam Insulation , International Journal of Heat and Mass Transfer.

9. Sheffield, C.F. (Sept. 15, 1988). Description and Application of a Gas Diffusion Model for Rigid Closed-cell Foams , Oak Ridge National Laboratory Symposium.

10.

10. Booth, J.R. (1993). An Evaluation of the Dow Thermal Performance Prediction Model for a Database of XPS/CFC-12 Aged Resistivity and Physical Properties , Journal of Thermal Insulation and Building Envelopes, 17: 154–170 .

11.

11. Reid, R.C., Prautsnitz, J.M. and Polling, B.E. (1987). Properties of Gases and Liquids, 4th edn., pp. 530–535, McGraw-Hill .

12.

12. Norton, F.J. (September-October 1982). Diffusion of Chlorofluorocarbon Gases in Polymer Films and Foams, J. Cellular Plastics, pp. 300–318.

13.

13. Shankland, I.R. (1990). CFC Alternatives for Thermal Insulation Foams , International Journal of Refrigeration, 13: 113–121 .

14.

14. Boy, E. (June 1997). Non-polluting Foaming, Kunststoffe Plast Europe, pp. 12–13.

15.

15. Booth, J.R. (Oct 4–6, 1993). Determination of Foam Cellular Structure by Thin Slice Accelerated Desorption of a Standard Gas , In: Proceedings, International Workshop on Longterm Thermal Performance of Cellular Plastics, SPI Canada.

16.

16. Park, C.P. (Aug. 1993). Diffusivity, Solubility, and Permeability of Blowing Agents in Polystyrene at Low Pressure , In: Proceedings, Symposium of Global Korean Scientists and Engineers, pp. 1076–1079 .

17.

17. Albouy, A., Roux, J.D., Mouton, D. and Wu, J. (1998). Development of HFC Blowing Agents. Part II: Expanded Polystyrene Insulating Boards , Cellular Polymers, 17: 163–176 .

18.

18. Wong, B., Zhang, Z. and Handa, Y.P. (1998). High Precision Gravimetric Technique for Determining the Solubility and Diffusivity of Gases in Polymers , J. Polym. Science Part B, Polymer Physics, 36: 2025–2032 .

19.

19. Bratt, C. and Albouy, A. (2001). Technical and Environmental Acceptance of HFCs as Blowing Agents for XPS Boards , In: Blowing Agents and Foaming Process, Foams Conference 2001, Paper No. 14, pp. 1–12 .

20.

20. Mizuno, K. and Yashiro, T. et al. (April 22–24, 2003). Estimation of Total Amounts of CFCs Banked in Building Insulation Foams in Japan , In: Proceedings, The Earth Technologies Forum, 2003.

21.

21. Japan Testing Center for Construction Materials, (March 2003). Research on the Recovery and Processing Technology of CFCS/HCFCS Contained in Thermal Insulators, Report on the Results in Fiscal 2002, Summary Report.

22.

22. Gueret, C., Dussaux, P. and Georges, W. (April 10, 2002). Evaluation Des Performances Thermiques D’isolant Preleve En Toiture Terrasse, CSTB Report HO 02-025 for Dow France, Paris, France.

23.

23. Georges, W. (March 1992). Evaluation De La Conductivite Thermique De L’isolant Roofmate SL Preleve En Toiture Terrasse, CSTB Report CSTB-ELT/HTO 92-02C for Dow France, Paris, France.