Viscoelastic behavior of carboxylated multi-walled carbon nanotube reinforced epoxy composites with various frequencies

An ultrasonically assisted stirring mixing process was used to fabricate epoxy composites filled with pristine carbon nanotubes (P-CNTs) and functionalized CNTs (M-CNTs). The viscoelastic properties of the resulting nanocomposites are systematically evaluated by dynamic mechanical thermal analyses (DMTA). Fourier transform infrared spectroscopy proves the existence of carboxyl groups on the surface of M-CNT. It is found that both the storage modulus and glass transition temperature increased with the addition of M-CNTs. Furthermore, the peak of loss modulus and loss tangent shift to higher temperatures and the width of their curves become wider when the loading frequency goes up for all the samples. This effect is attributed to the reduction in the mobility of the epoxy matrix and leads to the observed increase in thermal stability. In the present work, a kind of epoxy with increased glass transition temperature and high thermal stability is obtained.