Facile microwave synthesis of multi-walled carbon nanotubes for modification of elastomer used as heaters

Multi-walled carbon nanotubes (MWCNTs) were synthesized by a microwave method. MWCNTs had filamentous shapes (10 & mu;m) and were intertwined in bundles (40-60 nm diameter). The rapid oxidation of MWCNTs with a loss of 90% of weight was observed from 530 to 630 & DEG;C. 2% Residue was present at 630 & DEG;C, which gradually decreased to 1.2% at 1000 & DEG;C. In a silicone elastomer, increased thermal conductivity at a concentration of 8% MWCNTs was observed. The highest thermal conductivity of the nano-modified elastomer was 0.48 W/m & DEG;C with 8.0 wt% MWCNTs. The highest electrical conductivity was 2.4 x 10-5 S cm-1 at 8.0 wt% MWCNTs. Both the thermal and electrical conductivities showed percolation behavior with the percolation thresholds at 6 and 5 wt%, respectively. The MWCNTs synthesized by microwave method gave a good power economy in comparison to MWCNTs obtained by chemical vapor deposition (CVD) on NiMg catalyst. Microwave-synthesized MWCNTs showed high stability at a potential of 250 V in an electrical resistance heater application due to the presence of Fe on the surface of MWCNTs. The developed heater can effectively operate at 220 V, which enables the use of the tubes in household appliances, such as heat fans, irons, and washing machines.HighlightsSynthesis of MWCNTs by microwave plasma treatment of ferrocene and graphite.Characterization of MWCNTs by different techniques.Concentration dependence of electro- and thermal conductivity of MWCNTs in elastomers.Electro-physical parameters studies of elastomers modified with MWCNTs.Heat generation studies in elastomeric matrix with MWCNTs. Modification of elastomers using multi-walled carbon nanotubes for heaters.image