Sequential Dual Alignments Introduce Synergistic Effect on Hexagonal Boron Nitride Platelets for Superior Thermal...

Area of Science:

• Materials Science
• Nanotechnology
• Composite Materials

Background:

• Aligning 2D platelets in composites is difficult due to their complex orientational freedom.
• Existing methods for 1D material alignment are insufficient for 2D platelets.
• Achieving high thermal conductivity in polymer composites requires effective filler alignment.

Purpose of the Study:

• To develop a sequential dual-alignment approach for planar alignment of 2D platelets.
• To investigate the synergistic effect of combined shear and magnetic forces on platelet alignment.
• To enhance the thermal conductivity of modified hexagonal boron nitride (mhBN)/epoxy composites.

Main Methods:

• Utilizing an extrusion-printing-induced shear force for initial platelet alignment.
• Employing a rotating magnetic field to induce a force couple for further planar alignment.
• Embedding platelets within a yield-stress support bath during the alignment process.

Main Results:

• The sequential dual-alignment approach significantly improved planar alignment of 2D mhBN platelets.
• Thermal conductivity of 40 wt% mhBN/epoxy composite increased by 692% compared to unaligned composites.
• Achieved a 5-fold synergistic effect, surpassing the combined impact of individual alignment methods.
• Demonstrated improved thermal conductivity values for 30, 40, and 50 wt% mhBN composites compared to previous records.

Conclusions:

• The sequential dual-alignment method is effective for achieving superior planar alignment of 2D fillers.
• This approach offers a significant enhancement in thermal conductivity for composite materials.
• The developed method is suitable for fabricating 3D devices, such as heat sinks, with aligned conductive fillers.