  In this work we conduct a transient heat conduction experiment with an
aqueous suspension of nanoparticle disks of Laponite JS, a sol forming grade,
using laser light interferometry. The image sequence in time is used to measure
thermal diffusivity and thermal conductivity of the suspension. Imaging of the
temperature distribution is facilitated by the dependence of refractive index
of the suspension on temperature itself. We observe that with the addition of 4
volume % of nano-disks in water, thermal conductivity of the suspension
increases by around 30%. A theoretical model for thermal conductivity of the
suspension of anisotropic particles by Fricke as well as by Hamilton and
Crosser explains the trend of data well. In turn, it estimates thermal
conductivity of the Laponite nanoparticle itself, which is otherwise difficult
to measure in a direct manner. We also measure viscosity of the nanoparticle
suspension using a concentric cylinder rheometer. Measurements are seen to
follow quite well, the theoretical relation for viscosity of suspensions of
oblate particles that includes up to two particle interaction. This result
rules out the presence of clusters of particles in the suspension. The
effective viscosity and thermal diffusivity data show that the shape of the
particle has a role in determining enhancement of thermophysical properties of
the suspension.
