Differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, and ultraviolet-visible spectroscopy of gelatin and poly(vinyl alcohol) (PVA) homopolymers and their blended samples were studied. The data revealed that the gelatin and PVA polymers were compatible over the investigated range of compositions; this contributed to the formation of hydrogen-bonding interaction between their polar groups. The associated enthalpy-ofmelting transition and thermal stability of the blended samples increased with increasing PVA content. This indicated that the crystalline structure of PVA was not destroyed completely in the blends, which was consistent with the X-ray diffraction pattern of the 50/50 (wt %/wt %) blended gelatin/PVA sample. The absorption edge and optical band gap for allowed direct transition were determined from ultraviolet-visible spectra. The induced changes in the band structure are elucidated. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: [413][414][415][416][417][418][419][420] 2010
ABSTRACT:The electrical transport properties, such as direct current (dc) electrical conductivity ( s), dielectric constant ( 1), and dc current-time characteristics of unirradiated and g-irradiated pure and NiCl 2 -doped PVA were studied in the temperature range of 26-155ЊC. Quantitative analysis was carried out to determine the thermal activation energy of the conduction process, drift mobility, and carrier concentration. The thermally activated mobility of charge carriers is confirmed from calculations of drift mobility at different g-doses and temperatures. The results obtained revealed that g-irradiation enhances the conductivity. The dielectric constant data at different temperatures before and after irradiation can be attributed mainly to the changes in the intra-and intermolecular interactions. The dc conductivity at 30 and 40ЊC, activation energy in low temperature region I, and 1 max for 20 wt % NiCl 2 proved to be dosedependent. The obtained data suggests that these materials may have an application in dosimetry.
Acta Polymeriu 4 ' 2 (1991) Nr. 12 636 Sample SHARAF, KIlALED C t al.: Optical absorption in gamma irradiated poly(viny1 alcohol)-CoCI, composites Concen-Bi.lO-lo h?, Difference tration wt % s2m kg-I % (viscosity) of PAA (eq. (3))
Tuble 3. Comparison of the h?,-values measured by the viscosity method and calculated with eq. ( 3 )
Polymer composites of a system of Polyvinylpyrrolidone (PVP)/gelatin/DyCl3·6H2O were prepared in three groups that have different concentrations of PVP/gelatin contents to study the effect of neutron irradiation on their structural and optical properties. Results showed that the interaction of neutrons led to various complex phenomena, mainly bond breaking, main chain scission and intermolecular cross-linking. These processes introduced defects inside the material that were responsible for the changes in their optical and structural properties. All the calculated parameters were found to be dependent on the irradiation fluence in a uniform manner that makes these materials excellent candidates in the applications of dosimetry and radiology. Moreover, the sensitivity of the three groups of composites to the irradiation doses was found to be different. The variation in the structure of the composite group that contains the least PVP content was found to be less significant; hence, these materials were more stable against high doses that make them suitable for high radiation dose applications.
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