Polymer/Boron Nitride (BN) nanocomposite is promising interfacial material for cooling of electronic systems. It is important to determine percolation threshold when it practically uses in the industry. But, the exact prediction with existing model is still severe. Nano/micro sized air voids are necessarily interfered in the composites during the mixing process, which significantly influences on its thermal conductivity. We measured thermal conductivity of polymer/BN composite with different void contents and investigated the thermal transport mechanism of the composites with nano/micro sized air void in this research. Commercial BN powder was dispersed by sonication within acetone and mixed with biphenyl epoxy by using rotary paste mixer. The mixture was pressed by pellet press machine with different pressure and temperature in order to control the void content reproducibly. Void content and thermal conductivity of the samples were measured by mercury intrusion porosimetry and laser flash method, respectively. We compared the measured thermal conductivities with various thermal models for two-component mixture and chose proper models. Theoretical prediction is always higher than the measured value. It is shown that the prediction could be calibrated by replacing two-component model with three-component model that includes the air void component.
Journal: TechConnect Briefs
Volume: 1, Advanced Materials: TechConnect Briefs 2015
Published: June 14, 2015
Pages: 372 - 375
Industry sector: Advanced Materials & Manufacturing
Topic: Composite Materials