Thermal conductivity of highly loaded aluminium nitride–poly(propylene glycol) dispersions

Recently presented studies have revealed that micro-AlN–poly(propylene glycol) dispersions are of relatively low viscosity, shear-thinned, highly flowable and sufficiently time-stable. Such promising results have suggested that the fluids can be potentially applied as heat-transferring media. The AlN–PPG systems significantly differ from widely studied nanofluids, since they are highly loaded with micrometric solid phase. The presented paper focuses on three crucial features of AlN–PPG fluids – their stability, thermal conductivity and viscoelastic properties. Advanced analysis of AlN–PPG time stability was conducted in order to assess its applicable potential in thermal management technology. Thermal conductivity of AlN–PPG 425/2000 dispersions was measured and discussed. Thermal properties of the fluids were mostly dependent on their composition, i.e. solid phase loading and PPG molecular weight. Temperature did not substantially influence thermal conductivity of AlN–PPG fluids. Additionally, rheological response of AlN–PPG systems on oscillatory conditions was analysed. Linear viscoelastic range was determined and viscoelastic properties of the dispersions were recognised. The measurements provided useful rheological data about the structure of the dispersions and their temperature evolution