  Carbon-nanofillers are known for improving the desired properties of
polymers. The dispersion quality of nanofillers in the matrix is vital for the
fabrication of high-performance nanocomposites. An effective approach for
improving dispersion states of multi-walled carbon nanotubes (MWCNT) and
graphene nanoplatelets (GNPs) was employed via hybrid inclusion of the
nanofillers in polyurethane matrix to further enhancing viscoelastic
properties. Nanocomposites based on MWCNTs, two groups of graphene and hybrid
MWCNT/graphene with varied weight fractions and ratios were fabricated via a
simple, quick and scalable approach. Dynamic mechanical analysis results
indicated an improvement of up to 86% in storage modulus at 25C for hybrid
MWCNT/GNP-S750 at only 0.25 wt% loading, whereas solely MWCNTs and graphene
nanocomposites showed 9% and 15% enhancement at the same content, respectively.
The glass transition temperature value was enhanced by about 9.5 C with 0.25
wt% inclusion of well-dispersed three-dimensional MWCNT/GNP-S750 structure,
which disclosed a noticeable synergistic effect in thermomechanical properties.
