Impact of pore structure on the thermal conductivity of glass foams.

• Glass foams are made from CRT panel cullet, Mn 3 O 4 , carbon and alkali phosphates. • Pore structures are analyzed by X-ray tomography. • High porosity glass foams are obtained with varying average pore size. • The impact of pore size on the thermal conductivity is discovered. The thermal conductivity (λ) of glass foams is thought to depend on pore size. We report on the impact of pore size, determined using X-ray microtomography, and percentage porosity on the λ of glass foams. Glass foams were prepared by heating powder mixtures of obsolete cathode ray tube (CRT) panel glass, Mn 3 O 4 and carbon as foaming agents, and K 3 PO 4 as additive, to a suitable temperature above T g , and subsequent cooling. Here, we report for the first time a correlation between λ and pore size in the range 0.10–0.16 mm showing a decrease from 57 to 49 mW m−1 K−1 with increasing the pore size for glass foams with porosities of 87–90%. This indicates that the pore structure should be optimized in order to improve the insulating performance of glass foams. [ABSTRACT FROM AUTHOR]