Effect of fast neutrons on dielectric properties of pure and gelatin doped-poly (vinyl alcohol) films

Cast thin films of pure and gelatin doped poly(vinyl alcohol) (PVA) with co ncentrations of 2, 5, 7, 10, and 15 wt% were prepared and subjected to fast neutron fluences in the range of 10(5)-10(8) n/cm(2). The dielectric const ant (epsilon'), dielectric loss tangent (tan delta) and a.c. electrical con ductivity (sigma (a.c)) were investigated as a function of field frequency and temperature for all samples before and after irradiation. A clear glass transition peak was observed in epsilon'(T) and tan delta (T) curves. The irregular shift in the position of the glass transition temperature (T-g) i n tan delta spectra with increasing neutron fluence can be attributed to ei ther degradation or the predominance of the crosslinking process. The elect ric dipole moment and activation energy were calculated for pure and gelati n doped PVA samples before and after neutron irradiation.