ANISOTROPIC THERMAL CONDUCTIVITY ENHANCEMENT IN MAGNETICALLY ALIGNED POLYDIMETHYLSILOXANE/NICKEL COMPOSITE

The need for enhancing the thermal conductivity of Polydimethylsiloxane (PDMS) is increasing in applications such as microfluidics, flexible electronics, and biomedical devices. In this research, PDMS/Ni composites with embedded Nickel (Ni) particle columns, aligned under a static magnetic field, were studied for thermal conductivity enhancement. The volume fraction of Ni particles ranged from 2 to 20% but the strength of the applied magnetic field was fixed at 0.45 Tesla. The distribution and morphology of the column structures were quantitatively analyzed using optical microscopy (OM), scanning electron microcopy (SEM) and digital image processing. A reusable 3 omega measurement technique was applied to measure the effective thermal conductivity of PDMS/Ni composites in the parallel direction to the magnetic field. Under a static magnetic field, Ni particles align parallel to the field forming columns. The results illustrated that the diameter of Ni columns increased with increasing particle volume fraction while the center-to-center spacing between columns did not change substantially under the fixed magnetic strength. The magnetically aligned particle columns significantly enhanced the thermal conductivity of PDMS compared to the randomly distributed particles by about two fold.