Carbon nanotubes (CNTs) have outstanding characteristics including high mechanical properties

namely tensile strength and elastic modulus

and still remarkable flexibility

excellent thermal and electric conductivities

low percolation thresholds (loading weight at which a sharp drop in resistivity occurs) and high aspect ratios (length to diameter ratio

L/D)

while the latter provides the nanotubes with additional advantage over spherical fillers to obtain high property composites.Therefore

CNTs have the potential to act as a reinforcing filler of polymer matrices.The tetraglycidyl-4

4′-diaminodiphenylmethane (TGDDM) cured with 4

4′-diaminodiphenylsulphone (DDS) and filled with graphite or carbon fibers are commonly used as a polymeric matrix in high performance composites employed in the aircraft and spacecraft industries.In present paper

multi-walled carbon nanotubes (MWNTs) as a nanofiller were incorporated in the TGDDM/DDS epoxy.The thermal properties of the composites were studied by differential scanning calorimetry (DSC)

dynamic thermal analysis (DMTA) and thermalgravitimetric analysis (TGA).In addition

the dispersion of MWNTs in the epoxy was also investigated by scanning electron microscopy (SEM).In DSC studies

Kissinger and Flynn-Wall-Ozawa (FWO) methods were used to study the nonisothermal cure kinetics of the MWNTs filled TGDDM/DDS composites at different heating rates.The activation energy (Ea) of cure reactions of the MWNTs filled epoxy composites was obtained by Kissinger and FWO methods.For all composites

the Ea obtained by Kissinger method was slightly less than that of FWO method.With the addition of MWNTs

the Ea of the epoxy composites decreased first and then increased with the increase of the MWNTs contents.These results showed that the incorporation of carbon nanotubes accelerated the cure reaction of the TGDDM/DDS epoxy at lower MWNTs content due to the interaction between the hydroxyl groups on the surface of nanotubes and the epoxy.However

due to the high surface energy of carbon nanotubes

the viscosity of MWNTs/epoxy composites increased at higher MWNTs content.Hence

the mobility of hydroxyl groups was hindered

and the reaction energy of composites increased with increasing MWNTs contents.The influence of carbon nanotubes on the thermal stability of the epoxy was studied by TGA.It is shown that MWNTs had little influence on the thermal stability of the cured epoxy.The storage modulus and glass transition temperature of MWNTs filled TGDDM/DDS were investigated by DMTA.It is seen that the storage modulus of TGDDM/DDS system was enhanced with the increasing of MWNTs content

that is

the modulus increased 6.3% and 7.8% at 1 wt% and 5% MWNTs content

respectively.The glass transition temperature of the epoxy slightly decreased.Furthermore

the DMTA results of MWNTs/TGDDM/DDS composites were compared with that of carbon nanofibers (CNFs)/TGDDM/DDS composites.It was shown that the interactions between CNFs and epoxy were better those between that MWNTs and epoxy.The dispersion of carbon nanotubes in the epoxy was studied by SEM.The SEM results suggest that of MWNTs had poor dispersion in the cured epoxy.However

the radii of carbon nanotubes in the epoxy were greater than those of pure nanotubes.These results show the existence of interaction between carbon nanotubes and epoxy.