Thermal conductivity of polymer composites with oriented boron nitride

• Thermal conductivity depended on the orientation of BN in the polymer matrices.
• Hexagonal boron nitride (BN) particles were treated by C27H27N3O2 and C14H6O8.
• Amphiphilic-agent-treated BN particles are more easily oriented in the composite.
• BN/PVA composites with C14H6O8-treated BN showed the highest thermal conductivity.
• Thermal conductivity of the composites was compared with several theoretical models.

Thermal conductivity of boron nitride (BN) with polyvinyl alcohol (PVA) and/or polyvinyl butyral (PVB) was investigated as a function of the degree of BN orientation, the numbers of hydroxyl groups in the polymer matrices and the amphiphilic agents used. The composites with in-plane orientation of BN showed a higher thermal conductivity than the composites with out-of-plane orientation of BN due to the increase of thermal pathway. For a given BN content, the composites with in-plane orientation of BN/PVA showed higher thermal conductivity than the composites with in-plane orientation of BN/PVB. This result could be attributed to the improved degree of orientation of BN, caused by a larger number of hydroxyl groups being present. Those treated with C14H6O8 amphiphilic agent demonstrated a higher thermal conductivity than those treated by C27H27N3O2. The measured thermal conductivity of the composites was compared with that predicted by the several theoretical models.

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