DIELECTRIC INVESTIGATION ON POLY(METHYLMETHACRYLATE) FILMS DOPED WITHP-NITROANILINE

The dielectric behaviour of solution-grown thin films of poly(methylme thacrylate) containing p-nitroaniline (p-NA) as a dopant was investiga ted within the temperature range 60-90 degrees C and a 20-10(5) Hz fre quency band. It is shown that these mixtures exhibit only one relaxati on process similar to that of pure PMMA. However, the addition of p-NA increases both the height and the relaxation strength of the peaks an d also shifts log f(m) to higher frequencies. The additive causes narr owing of the loss curves and increases the activation energy for relax ation. These results are interpreted in terms of the hydrogen bonding effects of p-NA on localized motions of carboxymethyl dipoles in PMMA. An insight into the possible origins of the beta- and alpha-relaxatio ns in PMMA is also presented.