A Study on Molecular Motions through the Glass Transition of Styrene-Butadiene Rubber/Carbon Nanotubes Nanocomposites

Abstract

To fully exhibit the development of carbon nanotubes (CNTs) on the glass transition and molecular motions in styrene-butadiene copolymers, styrene-butadiene rubber/carbon nanotubes (SBR/CNTs) nanocomposites are prepared by latex mixing. The uniform dispersion of CNTs in matrix is guaranteed by this approach, which provides necessary conditions for studying the influence of CNTs on the motions of molecular chains. With increase of the CNTs loading, the storage modulus E ' of nanocomposites is correspondingly increased whereas tan δ is reduced compared with pure SBR. Furthermore, the glass transition is also moving towards higher temperature directly because the network structure is formed and endows stronger interaction between the fillers. Relaxation processes in polymers have been studied by dielectric spectroscopy. With the increase of CNTs loading in SBR matrix, the density of the packing network increases, and the free volume of the cavity would be smaller, which leads to the relaxation time of SBR/CNTs nanocomposites being longer than the pure SBR. It is found that the medium loading of CNTs are remarkably effective in improving the tensile strength of SBR.