Giant Dielectric Response in MWCNT/Chitosan Composite Films

In this work, xMWCNT/chitosan composite films with multi-walled carbon nanotubes (MWCNT) as filler and chitosan as matrix were prepared via a solution blending method. Varied content of MWCNT of 0, 0.5 wt.%, 1 wt.% and 1.5 wt.% was investigated. The dielectric properties of the films were investigated in the temperature range of -60 & DEG;C to 60 & DEG;C and frequency range of 10(2)-10(6) Hz. The experimental results show that the incorporation of MWCNT can effectively improve the dielectric properties of the film, with optimal results when the content of MWCNT is close to the percolation threshold. A giant dielectric constant (GDC) was found in all the samples and was studied by dielectric and impedance measurements. Maxwell Wagner relaxation was observed in all samples, which is caused by space charges at different interfaces. The GDC is thought to be related to a Maxwell-Wagner relaxation caused by sample-electrode contact. The addition of MWCNT can enhance the Maxwell-Wagner relaxation. The largest enhancement was found in the sample with 1 wt.% MWCNT.