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PVA/CuI polymer composite samples have been prepared and subjected to characterizations using FT-IR spectroscopy, DSC analysis, ac spectroscopy and dc conduction. The FT-IR spectral analysis shows remarkable variation of the absorption peak positions whereas DSC illustrates a little decrease of both glass transition temperature, Tg, and crystallization fraction, χ, with increasing CuI concentration. An increase of dc conductivity for PVA/CuI nano composite by increasing CuI concentration is recoded up to 15 wt%, besides it obeys Arhenuis plot with an activation energy in the range 0.54–1.32 eV. The frequency dependence of ac conductivity showed power law with an exponent 0.33 < s < 0.69 which predicts hopping conduction mechanism. The frequency dependence of both dielectric permittivity and dielectric loss obeys Debye dispersion relations in wide range of temperatures and frequency. Significant values of dipole relaxation time obtained which are thermally activated with activation energies in the range 0.33–0.87 eV. A significant value of hopping distance in the range 3.4–1.2 nm is estimated in agreement with the value of Bohr radius of the exciton.

The influence of coprecipitated barium ferrite (BaF) on the magnetic and mechanical properties of natural rubber-ferrite composites (RFCs) has been studied. Unusual characteristics of the BaF particles were revealed by a scanning electron microscope. The results show that the saturation magnetisation increases with increasing the ferrite content even for the considerably high BaF loading samples, whereas the coercivity is almost unchanged. The present RFCs recorded relatively low density 1?95 g cm 23 with high stored energy 1?26 MGOe at the maximum BaF loading of 220 phr. Both of the tensile strength and the elongation at break decrease with increasing BaF content. Evaluation of the swelling ratio was carried out to have an insight into the change in the mechanical properties of the RFCs at high BaF loading.

Correspondence to: M. H. M. Makled (makledmahmoud@ yahoo.com).