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This work presents the thermophysical properties of carbon nanotubes (CNT) and CNT/Al 2 O 3 hybrid nanofluids for heat transfer applications. An equal proportion of nanoparticles CNT (50%) and Al 2 O 3 (50%) were added to the base fluid for two different concentration of 0.05 and 0.1%. Results show that addition of Al 2 O 3 nanoparticles with CNT nanofluid improves the thermophysical properties. The thermal conductivity of hybrid nanofluids improved by 20% with a maximum concentration of 0.1%, while the thermal conductivity of CNT alone improved by only 8% with the base fluid. Similarly, density and viscosity of hybrid nanofluid increased up to 7 and 10%, respectively, while comparing it with the base fluid. The result of specific heat energy capacity of hybrid nanofluids increases to about 138% than CNT nanofluid with a maximum concentration of 0.2%.

Glass fiber reinforced epoxy matrix is modified with a hybrid combination of fillers, and composites were fabricated using the advanced pultrusion technique. The focus of the investigation was to comprehensively understand the synergy between the carbon nanofillers and the role of aluminum trihydride on the thermal characteristics. A ratio of 2 wt% of multiwalled carbon nanotubes and 3 wt% of graphene is established by prior optimization technique for improved thermal properties. Using X‐ray diffraction analysis, the presence of the two carbon fillers was confirmed. Aluminum trihydrate was incorporated in the epoxy matrix with the objective of improving the thermal properties. By thermogravimetric analysis and differential scanning calorimetry, assessment of the thermal properties of the composites has been undertaken. The use of the two carbon fillers leads to enhancement of the thermal properties and contrary to expectations, the composites with hybrid fillers undergo minimal degradation due to pyrolysis. Uniform dispersion of the nanoparticles and good interfacial bonding of fillers with the epoxy are observed to be critical for the enhancement of thermal properties. The ratio of the two carbon fillers used helps in their preferential alignment and hence significant improvements in thermal properties are observed. Glass transition temperature reveals a 13°C increase increases due to the inclusion of carbon nanofillers and aluminum trihydride.

The research work is carried out to analyse the electrical characteristics of glass fiber reinforced epoxy composites with the addition of multiwall carbon nanotubes and graphene nanoplatelets. The dispersion of 2wt.% multi walled carbon nanotubes(MWCNT) and 1-3wt.% graphene nanoplatelets (GNP) into the epoxy resin is assisted with high shear mechanical mixing followed by ultrasonication. The epoxy-filler mixture is transferred into temperature-controlled resin bath for pultrusion process. The pultrusion process helps to resolve major issues like poor dispersion and agglomeration of nanofillers in epoxy resin. The XRD and SEM analysis indicates that fillers are dispersed homogeneously in the epoxy matrix. The electrical conductivity ( ) and impedance (Z) are studied in the frequency range (10 Hz-8 MHz) with the variation in temperature (over 25°C-150°C). It is observed that the addition of two conductive nanofillers results in a synergistic effect at the percolation threshold, and the conductivity value increases by few orders due to the formation of a number of conductive paths in the composite. The complex impedance decreases with increase in frequency for the composites except for the sample with 3wt.% GNP and 2wt.% MWCNT indicating the semiconducting behaviour. The complex impedance plot is characterized by the appearance of a single semi-circular arc whose radii of curvature decreases with an increase in temperature, indicating the existence of electrical relaxation phenomena.