Effect of donor-acceptor sites at a barium titanate surface on the properties of composites based on cyanoethyl polyvinyl alcohol

Effect of the modification of barium titanate on the permittivity of its composites with cyanoethyl ester of polyvinyl alcohol

“…2). The established dependence agrees with previously obtained experimental data [8,9], and theoretical model [10], relating the growth of k with increase of the surface concentration of Brensted basic centers on the surface of a filler. A growth of the composite dielectric permittivity with increasing hydroxylation of the filler surface is likely due to a mobility increase of the hydroxyl groups, weakly bound with the surface, that determines their ability to a reorientation under an action of the exter nal electric field.…”

“…Following the previously optimized methods [8][9][10], the fillers were subjected to a dispersion in 5 ml of 30% CEPA solution (manufactured by AO "Plastopolymer", St. Petersburg, k ≈ 19), in dymethylformamide, with the design amount corresponding to 40 vol % of the filler in dry composite. After that, the specimens were placed in the closed glass vessels on rotating rollers and mixed within two hours.…”

“…By and large, the struc ture of such a material looks like a capacitor with suc cessive connection of different type materials, and for each composite, the dependence of k on the corre sponding values of its constituents proves to be non additive, being determined by the component per centage, and peculiarities of their contact and inter action. In a series of previously performed studies [8][9][10], it was shown that an optimal percentage of BaTiO 3 particles with a size in the range from 5 to 6 μm in CEPA based composites, which provides a maxi mal dielectric permittivity, is about 40 vol %. At higher percentages of the BaTiO 3 particles, a significant dete rioration of the dielectric properties of a composite occurs, caused by the agglomeration of filler particles, and correspondingly, by reduced homogeneity of their distribution in the filler, leading to a degradation of contact in the system CEPA BaTiO 3 .…”

“…In [8][9][10], different physical methods of BaTiO 3 modi fication were examined, such as thermal treatment, hydration, electron beam treatment, allowing to reach some increase of k under the optimal conditions of the process of treatment. This work is aimed at srudying the possibility to increase the dielectric permittivity of the composites involved at the expense of the surface mod ification of BaTiO 3 particles.…”

Improvement of vibrodamping properties of polyvinyl acetate–graphite composites by electron beam processing of the filler

“…In our earlier studies (Alekseev et al 2006 ; Myakin et al 2011 ) it was shown that such important performances of composites as homogeneity, permittivity, etc. can be improved by a specific modification of the dispersed filler surface in order to increase the amount of certain active centers responsible for acid–base interactions with the polymer binder.…”