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The relationship between the molecular and crystalline structure and the dielectric response of hot-pressed PVDF film and the films cast from N,N-dimethylacetamide solution was studied by means of wide angle X-ray scattering, Raman and dielectric spectroscopy. We have found that the degree of crystallinity of hot-pressed PVDF is by about 10% higher than that of solution-cast films, which results in a decrease in the activation energy of segmental motions and a rise in the freezing temperature. We have also observed that the solution-cast samples are more reach in sequences containing trans conformation (T)nG with n ≥ 3 which leads to an increase in their permittivity value. [ABSTRACT FROM AUTHOR]

The results of dielectric response studies of the biocellulose show that two relaxation processes can be distinguish: the local main chain motion at ˜200 K and an orientational motion in a mixed phase of polysaccharide and water at ˜325 K. The electroacoustic parameters of a loudspeaker with biocellulose membrane were measured in echoless conditions. The relationship between dielectric and mechanical properties of biocellulose was found. [ABSTRACT FROM AUTHOR]

Preliminary results of polymer poly(ethylene oxide) (PEO) with β-LiNH4SO4 (LAS) or Li(N2H5)SO4 (LHS) composites are presented. It was shown that Raman spectra did not reveal the existence of any complexes in the composites under studies. Electrical conductivity of the composites with LAS is about one order of magnitude higher than that for PEO and two orders higher than for LAS at room temperature, whereas for composites with LHS conductivity is lower than for LHS crystals. [ABSTRACT FROM AUTHOR]

Ferroelectric copolymers of vinylidene fluoride and trifluoroethylene irradiated with fast electrons were found to exhibit dispersive dielectric response, characteristic of ferroelectric relaxors and giant electrostriction. Here we report the results of our ESR, IR and Raman spectroscopy studies of radiation damage to the copolymers and relate the effects to the conformational disorder and dispersive dielectric response. [ABSTRACT FROM AUTHOR]

Diffuse X-ray scattering studies were performed for as grown Pb(Sc½Nb½)O3-PSN, Pb(Sc0.5Ta0.5)-PST and Pb(Sc0.5Nb0.2Ta0.3 )O3-PSNT single crystals at 400 K by means of a four-circle single crystal diffractometer equipped with CCD area detector. The superstructure observed yields a cubic unit cell with lattice parameter equals to 0.8181 nm, 0.8150 nm and 0.8140 nm for PSN, PST and PSNT crystals, respectively. The analysis of the extinction rules of diffuse reflections, observed for all the crystals in the superparaelectric phase, leads to a space group Pn&3macr;m instead of the Fm3m space group ascribed previously. [ABSTRACT FROM AUTHOR]

(NH 4 ) 3 H(SO 4 ) 2 , a member of M 3 H(XO 4 ) 2 hydrogen-bonded crystal family. The transition from the superionic phase (R &3macr; m) to the low-temperature phase (A2/a) at T s =413 K is accompanied by an anisotropic spontaneous deformation, which leads to the appearance of ferroelastic properties. The paper presents results of temperature variation of heat capacity, ferroelastic domain pattern and NIR Raman spectra in the close vicinity of T S . [ABSTRACT FROM AUTHOR]