الفهرس 
Dyes, radiation and polymers
Theoretical BackgroundOnly 14 pages are availabe for public view
 |  | from | 181 |  |  |
| | | from | 181 | | |
Abstract
In this work, PVA/PEG-EY blend structures are synthesized with different PEG concentrations, 0, 1, 3, 5, 10, 15 and 20 wt% in PVA. PVA/PEG-EY blend thin films have been prepared by using a solution casting process. The structure and morphological of PAV/PEG/EY blend composite film have been characterized by XRD, TGA, FT-IR, TEM, SEM, and Raman spectroscopy. Theoretical results of Raman spectra of PVA, PEG and EY individually calculated based on linear response time-dependent density functional theory, TDDFT, implemented using Gaussian 09 program, and compared with experimental results of the samples. The microstructure and defect distribution of the synthesized samples were inferred using the positron annihilation spectroscopy (PAS). Electrical and dielectric properties of the blend in specific ranges of frequency, 0.1 Hz to 2 x107 Hz, using impedance spectroscopy. The physical quantities ε, M, τ, σ
and Z are investigated. ε′, ε″ and tan δ, spectra show three distinguishable regions, while M′ and M″ spectra show two relaxation peaks in two different frequency regions, with the increase of frequency. Dielectric permittivity values increase randomly with increasing PEG content in the samples. The relaxation-time values corresponding to polymer chain segmental motion, i.e., τIP, τε, τtanδ and τM, vary monotonously with the increase of PEG concentration in blend matrix. τM, τIP, τε and τtanδ values increase randomly with increasing PEG content in the samples. With the increase of frequency,the σ’ values increase, with two regions, have two different linear behaviors are present clearly. σdc(II) values are found more than 10 times higher than that of σdc(I) values at room temperature. The values of Z′ and Z″ are largely decreased when the frequency is increased and showed three clearly distinct sectors. In Nyquist diagram, the increase of PEG concentration causes many variations of R, CPE, and W values at given frequency. The Woc1 was the highest for the PEG content x = 1, which represent an extraordinary increase attributed to increasing the charge capacitance and hence the diffusion process will be more effective.