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Vol 466, No 1 (2016)
- Year: 2016
- Articles: 7
- URL: https://journals.rcsi.science/0012-5016/issue/view/9192
Physical Chemistry
Electrically conductive nanocomposites with segregated structure based on poly(vinylidene fluoride-co-tetrafluoroethylene) and reduced graphene oxide
Abstract
An approach was described to obtaining polymer composites with segregated structure that have high electrical conductivity at low concentrations of an electrically conductive filler. According to this approach, thin layers of electrically nonconductive nanodispersed graphene oxide are applied to the surface of polymer particles and conduction is produced by heat and chemical treatments. Hot pressing of the modified powder leads to combination of layers of the graphene-like filler to form a single electrically conductive network. For the first time, reduction of graphene oxide on the surface of polymer particles with hydrazine vapor at room temperature was performed. Comparison of the electrical conductivities of composites obtained by the thermal and chemical methods of graphene oxide reduction showed that the chemical reduction method gives composites with higher conductivities than the thermal method does. The maximum conductivity (0.5 S/m) was reached in a composite containing 0.6% chemically reduced graphene oxide.
1-3
High-temperature heat capacity and thermodynamic properties of pyrovanadate Pb2V2O7 and orthovanadate Pb3(VO4)2
Abstract
The heat capacities of Pb2V2O7 and Pb3(VO4)2 as a function of temperature in the range 350–965 K have been studied by the differential scanning calorimetry method. The CP = f(T) curve for Pb2V2O7 is described by the equation Cp = (230.76 ± 0.51) + (73.60 ± 0.50)×10-3T − (18.38 ± 0.54)×105T-2 in the entire temperature range. For Pb3(VO4)2, there is a well-pronounced extreme point in the CP = f(T) curve at T = 371.5 K, which is caused by the existence of a structural phase transition. The thermodynamic properties of the oxide compounds have been calculated.
4-7
Stoichiography and fanlike separation of substances in dynamic mass-transfer processes
Abstract
For the first time, the concept of fanlike separation of substances in dynamic processes of homo- and heterophase mass transfer was introduced, which enables one to quantitatively determine the composi tions of mixtures of chemical compounds by stoichiographic calculations without selective separation of the mixtures.
8-11
Modified calculation scheme for evaluation and prediction of glass transition temperatures of polymers
Abstract
A modified calculation scheme was developed for evaluating and predicting the glass transition temperatures of linear and cross-linked polymers. It was proposed to separate the contributions of weak (dispersion) and strong (dipole–dipole and hydrogen bonding) interactions between the same atoms and polar groups in the backbone and side chains of a polymer. The considered model is based on analyzing the system of anharmonic oscillators formed by pairs of atoms entering the intermolecular interaction. The critical temperature of destabilization of this system of oscillators on heating is the glass transition temperature Tg. As a result, without resorting to correction factors of various kinds, one can calculate the Tg of a large number of linear and cross-linked polymers of different classes and various structures with good accuracy.
12-14
Spectroelectrochemical determination of the redox equivalent of magnesium porphine in the course of its electrooxidation
Abstract
The spectroelectrochemical method has been applied for studying the electropolymerization of magnesium porphine with the aim to determine the number of electrons consumed per monomer molecule, which allows one to find out the number of bonds between the units in the resulting polymer. Based on the results, a conclusion has been made about the structure of macrochains of the basic representative of a new family of electroactive materials, magnesium porphine
15-18
Nonmonotonic concentration dependences of elastic light scattering and its fluctuations in aqueous solutions
Abstract
A nonmonotonic bimodal dependence of elastic, Rayleigh scattering on the potassium phenosan concentration in an aqueous solution has been revealed. A similar dependence has been found, for the first time, for scattering amplitude fluctuations. The observed correlation is indicative of structural transitions in hydration shells of potassium phenosan, which are responsible for the increase and scatter of their size comparable with the wavelength (527 nm) of a laser spectrometer.
19-22
Surface enhanced Raman scattering detection of water-soluble derivatives of fullerene C60 and their covalent conjugates with dyes in biological model systems
Abstract
The potential of surface enhanced Raman spectroscopy (SERS) for the detection of water-soluble fullerene derivatives and their covalent conjugates with xanthene dyes was investigated in model biological liposome membranes and in the albumin protein structure. It was shown that in liposomes and in albumin, fullerene derivatives and their covalent conjugates with dyes show characteristic SERS spectra, which allows detection of water-soluble fullerene derivatives in phosphatidylcholine liposomes at the lipid/fullerene derivative ratio of 100 as well as fullerene–dye conjugates in liposomes and albumin.
23-27