Mechanical and Morphological Properties of Short Nylon Fibers and Carbon Nanotubes Reinforced NR/SBR Nanocomposites

Abstract

Hypothesis: Short fibers can be incorporated directly into the rubber compound along with other nanoparticles. The state of filler dispersion and orientation in the matrix, their size and aspect ratio as well as the interactions with the rubber chains have been shown to be crucial parameters that determine the reinforcing ability of these fillers. These nanocomposites are light weight and there is tremendous potential in stiffness/weight ratios over conventional materials. In this study, nanocomposites of (NR/SBR) elastomer/short nylon fiber with different amounts of carbon nanotubes were prepared in the presence ofhydrated silica-resorcinol-hexamethylene tetramine (HRH) as bonding agent.Methods: Natural rubber and styrene butadiene rubber (NR/SBR), reinforced with short nylon fibers and carbon nanotubes, were prepared in a two-roll mill mixer. The effect of different amounts of modified and unmodified multiwall carbon nanotubes (MCNTs) between 0 and 3 phr on the mechanical properties, structure and morphology of nanocomposite samples were investigated. The adhesion of the fiber to the rubber matrix was enhanced by the addition of a dry bonding system consisting of HRH. The structure of nanocomposites was studied by scanning electron microscopy (SEM). Findings: By enhancing the amount of modified carbon nanotube and unmodified carbon nanotube, the curing time and the swelling index decreased, while the curing rate and maximum torque increased. The mechanical properties, tear strength, hardness and compressibility were increased as the content of modified and unmodified multi-wall carbon nanotubes increased in both directions of longitudinal (L) and transverse (T) in the nanocomposite. The resilience of nanocomposites was reduced by increasing the carbon nanotube content, and there was a further decrease in the modified nanotube. The microscopy results indicated that by adding carbon nanotubes, specially modified carbon nanotube in longitudinal direction, the fibers pull out and hollow holes decreased at the fracture surface due to the strong bond between the rubber matrix and the fibers and carbon nanotubes. In transverse direction, there was increased pull out and weak bonding.

Keywords

• nanocomposite
• short nylon fibers
• carbon nanotube
• nr/sbr rubber
• mechanical and morphology properties