Characterization of solution casting derived carbon nanotube reinforced poly(vinyl alcohol) thin films

Carbon nanotube (CNT) reinforced polyvinyl alcohol (PVA) composite thin films have been prepared by a solution casting process at room temperature using gum acacia as a surfactant. CNT contents in the composites were varied from 5 to 10% by weight to increase its electrical conductivity. Electrical properties, such as conductivity, capacitance, dielectric constant and loss tangent, of the composites were investigated. All the electrical properties were found to be improved with the incorporation of CNTs. The absorbance and transmittance of light were determined by UV–visible spectroscopy and from the transmittance data, band gaps were calculated. The smallest band gap, of 1.18 eV, was found for the 10% CNT containing composite while the 0% CNT containing composite had a band gap of 2.4 eV. Thermal properties of the films were characterized by a thermo mechanical analyzer. The experimental results revealed that the blended films exhibited higher stability and improved thermal properties, which suggests the occurrence of an interaction, detected by FTIR, among PVA, CNT and water molecules in the films. The mechanical properties, tensile strength, elongation at break and Young modulus, were found to be improved. Water absorption properties of the composites were found to decrease with the increase of CNT content. The lowest water uptake properties and highest thermal stability were demonstrated by 10% CNT containing film. All of the results indicated that the developed PVA/CNT composite might be promising for use in optoelectronic application.