Influence of preparation methods on the electrical and nanomechanical properties of poly(methyl methacrylate)/multiwalled carbon nanotubes composites
Abstract
Poly(methyl methacrylate)/multiwalled carbon nanotubes (PMMA/MWCNT) composites were prepared by two different methods: melt mixing and solution casting. For solution casting, two different solvents, toluene and chloroform, were used to prepare PMMA solutions with different concentrations of MWCNT.
The dispersion of the CNT in the composite samples was verified by scanning electron microscopy. For the nanocomposites prepared by both methods, the electrical conductivity increased with increasing filler content, showing typical percolation behavior.
In addition, an increase of 11 orders of magnitude in the electrical conductivity relative to the matrix conductivity was determined by broadband dielectric spectroscopy and four probe conductivity measurements. A maximum value of sigma(DC) approximate to 1.6 S/cm was found for the highest filler loaded sample (3.67 vol %), which was prepared by solution casting from toluene.
Nanoindentation analysis was used to characterize the surface mechanical properties of the composite samples prepared by the different methods. Indentation tests were performed at various penetration depths, and it was revealed that the melt mixing process resulted in stiffer neat PMMA samples compared to the solution casted PMMA samples.