Enhanced thermal conductivity for polybenzoxazine matrix composites by constructing a hybrid conductive network and modification of fillers

Abstract

Polyhedral oligomeric silsesquioxanes (POSS) and γ-glycidoxy propyl trimethoxy silane (KH560) were applied to modify boron nitride (BN) and boron nitride whisker (BN_w), and modified BN (m-BN) and modified BN_w (m-BN_w) were added as thermally conductive fillers to polybenzoxazine (PBz) matrix to synthesize m-BN/m-BN_w/PBz composite by hot press. The research results indicate that the modification of BN and BN_w and the synergistic effect between m-BN and m-BN_w can significantly improve the thermal conductivity of PBz composite. The thermal conductivity of PBz composite with 25 wt % m-BN and 25 wt % m-BN_w reached to 1.27 W/mK, which is 35% higher than PBz composite with 50 wt % m-BN (0.94 W/mK), 76% higher than PBz composite with 50 wt % BN (0.72 W/mK), and also display excellent electrical insulation performance. The corresponding dielectric constant (ε) and dielectric loss (tan δ) were 3.83 and 0.0078, respectively. Besides, the T_{heat-resistance index} (T_HRI) of PBz composite with 25 wt % m-BN and 25 wt % m-BN_w is 242.26 °C, and the thermal degradation temperature at 30% weight loss (T₃₀) is 557.72 °C, are higher than PBz matrix (224.46 and 498.88 °C). And the tensile strength of PBz composites with 25 wt % m-BN and 25 wt % m-BN_w is 47.71 MPa.

Graphical Abstract

Keywords:

• Polybenzoxazine
• boron nitride
• boron nitride whiskers
• synergistic effect
• polyhedral oligomeric silsesquioxanes
• thermal conductivity

This research was financially supported by the National Science Foundation of China (No. 51572154).