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.

Attenuation of Fluorocarbons Released from Foam Insulation in Landfills

“…Since the HFCs seem persistent in landfill environments a larger fraction of the HFC disposed of in foam waste a The table also presents the effect of lower degradation rate coefficient (a factor of 10; 0.1k1) and a higher diffusion coefficient (a factor of 10; 10D). b Diffusion coefficients used: 2.0‚10 -14 m 2 s -1 (CFC-11)(4); 2.9‚10 -14 m 2 s -1 (HCFC-141b)(4); 5.1‚10 -14 m 2 s -1 (CFC-12)(36); 5.4‚10 -12 m 2 s -1 (HCFC-22) (36). The degradation rate coefficients, k1, in the runs with MOCLA-FOAM are average microcosm rates based on values listed in Table 2 (0.309, 0.029, 0.015, and 0.016 for CFC-11, CFC-12, HCFC-22, and HCFC-141b, respectively).…”

Global Atmospheric Emissions Model of HCFC142b with Respect to Extruded Polystyrene Foam Applications

“…Indeed, the UNEP reports and Task Force groups have worked to resolve this matter [1,[12][13][14][17][18][19][20]24]. To this end, it is important that predictions of the emission rates of these substances be accurate and reliable [16]. At the very least, reliability of the models is enhanced when the trends in atmospheric measurements are consistent with production and use data [27,29].…”

Foam extrusion behavior, morphology, and physical foam properties of organic cellulose ester

“…1,2 In addition, hydrocarbons such as butane or pentane as well as fluorohydrocarbons such as HFC 134a or HFC 245fa still are the major industrially used blowing agents to produce thermoplastic foams. [3][4][5] The use of renewable resources, the reduction of packaging waste, and the minimization of emissions become more and more important with respect to a more sustainable economy. Traditional foam polymers as well as most of the conventional blowing agents used do not fulfill all of the requirements for sustainability.…”