This paper is devoted to the study of the structure and thermomechanical properties of PVDF-based ferroelectric polymer film. Transparent electrically conductive ITO coatings are applied to both sides of such a film. In this case, such material acquires additional functional properties due to piezoelectric and pyroelectric effects, forming, in fact, a full-fledged flexible transparent device, which, for example, will emit a sound when an acoustic signal is applied, and under various external influences can generate an electrical signal. The use of such structures is associated with the influence of various external influences on them: thermomechanical loads associated with mechanical deformations and temperature effects during operation, or when applying conductive layers to the film. The article presents structure investigation and its change during high-temperature annealing using IR spectroscopy and comparative results of testing a PVDF film before and after deposition of ITO layers for uniaxial stretching, its dynamic mechanical analysis, DSC, as well as measurements of the transparency and piezoelectric properties of such structure. It is shown that the temperature-time mode of deposition of ITO layers has little effect on the thermal and mechanical properties of PVDF films, taking into account their work in the elastic region, slightly reducing the piezoelectric properties. At the same time, the possibility of chemical interactions at the polymer–ITO interface is shown.
The effect of plant-based fillers on thermal resistance in highly filled biocomposites based on ethylene–vinyl acetate copolymer (EVA) was studied. Wood flour and microcrystalline cellulose were used as fillers. It was shown that the introduction of microcrystalline cellulose into EVA did not affect the thermal stability of the polymer matrix. In contrast, the introduction of wood flour into EVA led to a significant increase in the thermal stability of the entire biocomposite. Oxidation induction time increased from 0 (pure EVA) to 73 min (EVA + wood flour biocomposites). The low-molecular weight phenolic compounds contained in wood flour are likely able to diffuse into the polymer matrix, exerting a stabilizing effect. The discovered stabilizing effect is a positive development for expanding the possibilities of technological processing of biocomposites, including multiple processing.
5 April 2018 in Russian Journal of Physical Chemistry A
An improved way of measuring the specific surface area of carbon materials that is based on the adsorption of methylene blue is proposed. It is found that the proposed method is more accurate for...
Anionic homo- and copolymerization of p-diethynylbenzene in the presence of n-BuLi in polar solvents was carried out. The use of hexamethylphosphortriamide (HMPA) makes it possible to synthesize a completely linear soluble polymer that does not have branching and phenylene fragments. A copolymer of p-diethynylbenzene with diphenyldiacetylene was synthesized. Homo- and copolymers of p-diethynylbenzene have high thermo- and thermo-oxidative stability. By the interaction of side reactive ethynylphenylene groups with various reagents, it is proposed to synthesize clusters along the conducting chain of poly-p-diethynylbenzene. Due to presenting C≡CH side groups, boron, copper, and cobalt derivatives were synthesized. It is shown that not all theoretically possible stereoisomers can be formed as a result of the polymerization. The application of p-diethynylbenzene polymers for the modification of industrial samples of epoxy novolac resin, oligoester acrylates, and carbon fibers has been demonstrated.
16 August 2022 in Journal of Applied Polymer Science