Correlation between the elastic modulus and heat transport along the solid phase in highly porous materials: Theoretical approaches and experimental validation using polyurea aerogels

• Correlation between elastic modulus and solid phase thermal conductivity.
• Impact of the micro-structural changes on macroscopic properties.
• Impact of micro-structural changes on the correlation.
• Correlation derived from theoretical approaches.
• Strategies for decoupling.

The elastic modulus and solid phase thermal conductivity were experimentally determined for two series of supercritically dried polyurea aerogels. Both sample series cover a density range between 0.03 and 0.3 g/cm3, respectively, while micro-structural details of the aerogels are completely different for the samples of the two series, thus leading to considerable differences in macroscopic properties, when comparing two samples from the two series at a given density. On the contrary, elastic modulus is found to strongly correlate with the heat transport along the solid phase, irrespective of the sample series considered. The insensitivity of this correlation to micro-structural details can be explained with theoretical approaches that are used to describe the macroscopic properties of porous materials. However, also possibilities for a structural decoupling of the elastic modulus and the heat transport along the solid phase could be identified that may open new approaches for technical applications.

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