Thermal Conductivity of Concentrated Colloids in Different States

The thermal conductivity of concentrated colloids in fluid, glass, and gel states was analyzed. SiO2 colloids at 10-31 vol % and Al2O3 colloids at 4.8 vol To in the fluid, the gel, and the glassy states were studied by dynamic light scattering, rheology, and transmission electron microscopy. Thermal conductivity of the three states was measured as a function of volume fraction. For the fluid and gel states the thermal conductivity increases almost linearly with concentration, reaching roughly 18% enhancement for silica at a volume fraction of 31 vol %. In contrast, in the glass state thermal conductivity strongly decreases with increasing volume fraction.