研究目的
To find a method that allows an estimation of how the radiative thermal conductivity is affected by the opacifiers in polystyrene foams.
研究成果
The addition of opacifiers significantly reduces radiative thermal conductivity in polystyrene foams. Two modeling methods were validated and show good agreement with experimental data, enabling prediction of insulation performance. This facilitates optimization and development of opacified foams for improved energy efficiency in building insulation.
研究不足
The first method requires thin foils with exact opacifier concentration, which was challenging for concentrations above 2.5 wt% due to low transmittance. The model assumes uniform cell geometry and isotropic scattering, which may not fully capture real inhomogeneities. Uncertainties in measurements and calculations are around 10-12%.
1：Experimental Design and Method Selection:
Two methods were developed to calculate the spectral specific extinction coefficient of opacified foams. The first method integrates the refractive index of opacified bulk material into geometric cell structure, based on a model by Placido et al. The second method adds the extinction coefficient of the opacifier in powder form to that of the standard foam without opacifier.
2：Sample Selection and Data Sources:
Two extruded polystyrene (XPS) foams were used: SFB-V (standard, not opacified) and SFX-V (opacified with 3 wt% carbon black). Samples were cut into thin slices for measurements.
3：List of Experimental Equipment and Materials:
Fourier Transform Infrared (FTIR) spectrometer Bruker Vertex 70v, integrating sphere, Scanning Electron Microscope (SEM), guarded hot plate apparatus, carbon black opacifier (Thermax? N990, particle size 300 nm).
4：Experimental Procedures and Operational Workflow:
Infrared-optical properties were measured using FTIR spectrometer with integrating sphere for transmittance and reflectance. Spectral effective specific extinction coefficient and albedo were calculated using three-flux solution. Cell morphology was characterized with SEM. Thermal conductivity was measured according to DIN EN
5：Data Analysis Methods:
126 Spectral data were analyzed using three-flux approximation, Mie theory for struts, and geometrical optics for walls. Total extinction coefficient was integrated using Rosseland weight function. Uncertainties were propagated statistically.
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