Thermal expansion behavior of CNT/Ag nanocomposite

Abstract

Abstract In the present study, the molecular level mixing method has been extended to fabricate carbon nanotube based silver nanocomposite. Here, the influence of types of carbon nanotubes and their functionalization on the coefficient of thermal expansion was examined. Covalently and non-covalently functionalized single wall as well as multiwall carbon nanotubes were used in the synthesis process. The microstructural features of the composite revealed that the carbon nanotubes decorated with silver nanoparticles were dispersed embedded and anchored in the silver matrix. Experimental results confirmed that the coefficient of thermal expansion of the composite reduces in relation to that of pure silver, with increasing content of carbon nanotubes in the silver matrix. The thermal expansion of nanocomposites, up to 6 volume percent of nanotubes, reduces to 50 – 60 % that of pure silver. However, more reduction in thermal expansion of silver nanocomposite with single wall carbon nanotube than with multiwall nanotubes has been observed, which is correlated with high aspect ratio and large effective surface area of single wall nanotubes. Moreover, covalently functionalized multiwall nanotubes exhibit more reinforcing effect than non-covalently functionalized. We believe that strong bonding between carbon nanotubes and metal matrix due to covalent functionalization is responsible for effective reduction in thermal expansion.