Improved thermal conductivity of fluids and composites using boron nitride (BN) nanoparticles through hydrogen bonding

Abstract

A new method, which utilized hydrogen bonding to enhance the effective thermal conductivity of materials is presented and discussed. Spherical boron nitride (BN) nano particles were mixed and exfoliated to form hydrogen bonds between the particles, fluids, and polymer solutions containing glycerol, water, krytox oil, polyurethane solutions, and other similar substances. The resulting long chain carbon fibers were found to significantly enhance the thermal conductivity of these substances, due to increases in the contact and interfacial surface area. The experimental results indicated that a 35 wt% BN loading in polyurethane could increase the effective thermal conductivity of the base polyurethane composite to a value of 1.78 W/mK, which is a 390 % increase over the base polyurethane composite. In addition, a 20 wt% BN loading in polyurethane with a 5 wt% carbon fiber loading, was found to increase the effective thermal conductivity to a value of 2.10 W/mK, or a 480 % increase over the base polyurethane composite. These results are among the highest values ever reported and can in part, be attributed to the three roll-milling technique utilized to enhance the contact. This work may open the way to further explore enhanced thermal materials with numerous and significant potential commercial applications.