Title

Correlation of Microstructure and Thermal Conductivity in Nanoporous Solids: The Case of Polyurea Aerogels Synthesized From an Aliphatic Tri-isocyanate and Water

Abstract

This study correlates microstructure with thermal transport properties in nanoporous solids. The model system is based on polyurea (PUA) aerogels. Those aerogels demonstrate a dramatic change in microstructure with density. Low density aerogels consist of entangled nano-fibers changing into interconnected nanoparticles as the density increases. The nanostructure was probed in terms of both particle size and network interconnectivity with scanning electron microscopy and small angle X-ray scattering. Thermal conductivity values between 0.027 and 0.066 W/mK were obtained with the hot-wire method for PUA samples with densities between 0.04 and 0.53 g/cm3. Both, pressure and temperature dependent experiments were performed for the deconvolution of total thermal conductivity into gaseous, radiative, and transport-through-the-solid- framework contributions. Subsequently, thermal conductivity along the solid framework was considered as a function of microstructure. That leads to a quantitative evaluation of the impact of primary particle characteristics and network interconnectivity on the solid thermal conductivity. © 2013 Elsevier B.V. All rights reserved.

Department(s)

Chemistry

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2013 Elsevier, All rights reserved.


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