Improving the Delamination Resistance and Thermal Conductivity of Composites by Growing Vertical Carbon Nanotube Arrays on Carbon Fibers to Induce Vertical Orientation of Liquid Crystal Epoxy Resin

Conventional carbon fiber/epoxy resin-based composites are widely used due to their high specific strength. However, typical laminated composites have poor resistance to delamination as well as thermal conductivity in the thickness direction due to poor interfacial bonding, lack of high-strength load-bearing medium between layers and lack of continuous interlayer continuous thermal conductive path. In this work, vertical arrays of carbon nanotubes are grown on the surface of carbon fiber cloth by chemical vapor deposition and combined with liquid crystal epoxy resin. Observations by X-ray diffraction as well as polarized light microscopy showed that the liquid crystal epoxy molecules were oriented along the direction of the carbon nanotube arrays grown on the surface of the carbon fiber cloth, forming an intrinsic interlaminar reinforced structure along the Z-direction of the composite, which also acts as continuous high thermal conductivity heat transfer path between the layers of the composite. The strength of the material in the Z-direction as well as the thermal conductivity are enhanced by the interlayer Z-directional orientation reinforcement and the formed 3-dimensional continuous heat transfer network, resulting in an increase of 56.4% in ILSS and 70.6% in thermal conductivity in the thickness direction.