Effect of hydroxylated carbon nanotubes on the thermal and electrical properties of derived epoxy composite materials

Carbon nanotubes are efficient thermal conductors and exhibit unique electrical properties. What is not entirely clear, however, is how to effectively transfer the carbon nanotube's unique attributes exhibited at the nanoscale to the macroscale. The primary focus of this study was upon identifying the main causes that can lead to improvements in thermal and electrical conductivity for polymers with the use of the reinforcement material. The effects of carbon nanotube type and structure on the physical properties of derived epoxy composite materials were investigated experimentally to better understand the applied physics of thermal and electrical transport at the nanoscale. The thermal and electrical properties of the composite materials were also investigated theoretically with various models. The results indicated that the hydroxyl functionalization of carbon nanotubes can be an effective means to enhance the thermal and electrical properties of the derived composite materials. Hydroxyl-functionalized carbon nanotubes exhibit considerably improved thermal and electrical conductivity in applications including polymer composites. Hydroxylated carbon nanotubes can achieve at least one or more of the following objectives: improves the solubility and dispersibility of the carbon nanotubes in polymer materials into which the carbon nanotubes are to be mixed, reduces contact resistance between carbon nanotubes incorporated into the polymer material by drawing the carbon nanotubes closer together, and provides a conductive bridge between carbon nanotubes to reduce the electrical contact resistance there between. Multi-walled carbon nanotubes can reduce the probability of inelastic phonon scattering due to grain boundaries, thereby yielding a higher effective thermal conductivity for derived polymer composite materials.