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ABSTRACT:The dipolar relaxation in poly(vinyl alcohol) (PVA), sodium carboxy methyl cellulose (NaCMC s ), and their blends were studied using a thermally stimulated depolarization current (TSDC) technique. The mutual effects of polarization conditions such as heating rate, poling temperature, time, and field on the properties of TSDC were investigated. Quantitative analysis of the experimental data is given in terms of dipolar and space charge polarization. A thermal sampling (TS) technique was applied to decompose the complex relaxations in individual polymers and their blend of 0.5/0.5 wt/wt into its normal distribution components. The activation energy of TS-formed electrets was determined by fitting the experimental curve to Bucci and Fieschi equations. Peak parameters such as activation energy and preexponential factor 0 were obtained. A linear relationship between the activation energy and logarithm of the preexponential factor was found, thus confirming operation of the compensation law. In addition, by using the Eyring equation of the rate theory, the activation enthalpy ⌬H and the activation entropy ⌬S were calculated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: [1342][1343][1344][1345][1346][1347][1348][1349][1350][1351][1352][1353] 2005

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SYNOPSISThe electrical transport properties including electrical conductivity ( s), dielectrical constant (e), thermally stimulated depolarization current (TSDC), and pyroelectric coefficient ( P) of a poly(vinyl alcohol)-polyethylene (PVA-PE) copolymer were studied in the temperature range 296-433K. Two stages of behavior have been observed with activation energies 1.49 and 0.05 eV. Discussion of conduction mechanism was carried out in terms of relevant theories. The existence of a relaxation peak in e versus T relation has been analyzed taking into consideration space charge effects and dipole orientation phenomena. The TSDC spectra showed two peaks with differing intensity and position independent of field intensity. Pyroelectric current data provide further support to space charge effects.