Study on Different Solution-Cast Films of PMMA and PVAc

Transparent films of PMMA (poly methyl methacrylate) and PVAc (polyvinyl acetate), previously dissolved in chloroform, toluene and tetrahydrofuran (THF), were prepared by using solution-cast technique. FT-IR transmission spectra were obtained from the samples. Also, different concentrations of PMMA/PVAc blend, dissolved in chloroform, were prepared by the same method. From absorption, transmission and specular reflection spectra, the absorption coefficient (a) and refractive index (n) have been calculated at room temperature and also after heating. The values of the optical band gap (E-g) have been obtained from the direct allowed transitions in k-space. In addition, the values of width of the tails of localized states in the band gap (E-u) were evaluated from Urbach edges.