Enhancement of thermal conduction of polyimide/boron nitride nanocomposites

Two kinds of polyimide-boron nitride (PI-BN) nanocomposite have been manufactured by the direct blending process using two different kinds and sizes of BN nanoparticles, referred as BN-1 and BN-2. A high power ultrasonic probe has been used to achieve the dispersion of BN nanoparticles within the polyimide precursor solution. Thermal conductivity has been evaluated for filler volume content up to 29.1% vol. for PI-BN-1 and 57.3% vol. for PI-BN-2. Thermal conductivity has been measured using a pulsed photo-thermal technique developed for determining the thermal properties of solid thin-films and coatings. The use of BN nanoparticles allows thermal conductivity to be increased but the observed increase depends strongly on the nanoparticle diameter. Thermal conductivity increases from 0.21 W/mK for the neat polyimide (PI) to 0.56 W/mK for the PI-BN-1 (29.1% vol.) However, when using lower size BN nanoparticles the thermal conductivity only increases up to 0.25 W/mK for the PI-BN-2 for higher volume content (57.3% vol.).