Optical characterization and differential scanning calorimetry studies of carboxymethyl cellulose-nickel chloride composite system

Carboxymethyl cellulose (CMC) films doped with nickel chloride hexahydrate have been prepared by casting technique. The phase transitions and thermal stability of the prepared samples were investigated by differential scanning calorimetry and thermogravimetry. The optical absorption was recorded at room temperature in the wavelength range of 190–2500 nm. From the absorption edge studies, the values of the Urbach energy (Ee) were found to be 0.58 eV in case of the pure polymer; however, the Urbach energy values were found to be in the range of 0.64–1.0 eV under additional different percentages of nickel chloride. These energy values indicate that the model based on random fluctuations of the internal fields associated with structure disorder is preferable and transitions are made between band tails. Refractive index, complex dielectric constants have also been determined. Color properties of the prepared samples are discussed in the frame work of CIE L*u*v* color space. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013