Influence of Polymer Nature on Electroadhesion.

Electroadhesive systems are promising for creating delicate robotic manipulators operating both in the natural environment and in space conditions. Using thermosetting epoxy resin, polyurethane and polyester resin as examples, the influence of the polymers' natures, potential differences and current strengths on electroadhesive interactions in polymer-polymer systems was studied. The investigations were carried out by recording the force of normal separation of substrates from electroadhesives using contact and contactless methods at various electrical parameters of the systems and their components.

Proton irradiation Of GaO Schottky diodes and NiO/GaO heterojunctions.

p-NiO/n-GaO heterojunction (HJ) diodes exhibit much larger changes in their properties upon 1.1 MeV proton irradiation than Schottky diodes (SDs) prepared on the same material. In p-NiO/GaO HJ diodes, the narrow region adjacent to the HJ boundary is found to contain a high density of relatively deep centers with levels near E-0.

Dynamics of optical properties of sequentially diluted lucigenin aqueous solutions according to luminescence data.

The article discusses optical properties (luminescence) of diluted (24 dilution factor) lucigenin () aqueous solutions. Six series of aqueous solutions, with 50 samples in each series, were studied. The series were diluted on different days within random schedules, following a unified procedure: the first sample in all the series was the (C = 8.

Regulation of the Phase Structure in the Crystallizing Curing System PCL-DGEBA.

Qualitative and quantitative aspects of the formation of various types of phase structures, sizes and compositions were considered. For the studied polycaprolactone-epoxy resin/4,4'-diaminediphenylsulfone system, a phase diagram characterized by amorphous separation with a lower critical solution temperature was constructed and its evolution was traced with increasing conversion degree of epoxy groups. A method is proposed for determining the temperature-concentration parameters that determine the type of phase structure of composite materials, based on the optical interferometry method.

Phase Equilibria and Interdiffusion in the Ternary System Epoxy Oligomer-Polysulfone-Alkyl Glycidyl Ether.

Phase equilibria, interdiffusion and structure in the initial uncured mixtures of epoxy oligomer-polysulfone-alkyl glycidyl ether were studied. Binodal curves were constructed on isothermal sections of the ternary phase diagram. Thermodynamic mixing parameters were calculated and spinodal curves were plotted.

Determination of Pair Interaction Parameters of Multicomponent Polymer Systems.

From the examples of three and four-component polymer-polymer systems characterized by amorphous separation, an original technique for determining the pair parameters of interaction between components based on the sorption isotherms of common solvent vapor, particularly water vapor, has been developed. The possibility of calculating thermodynamic characteristics of multicomponent polymer compositions with specific interactions of functional groups from experimentally obtained sorption isotherms is shown. An algorithm for calculating pair interaction parameters, estimating concentration dependences of chemical potential and Gibbs free energy of mixing, and predicting the phase state of polymer mixtures was presented for the first time for such systems.

Effect of Molecular Weight on Phase Equilibrium in the Polystyrene-Poly(methyl methacrylate) System.

Data on the solubility of oligomer polystyrene (PS) and poly(methyl methacrylate) (PMMA) of various molecular weights have been obtained. The binodal and spinodal curves of the phase state diagram with the upper critical solution temperature (UCST) are constructed through simulation within the framework of the Flory-Huggins theory. The influence of the molecular weight of polymers on the contribution to their mixing has been compared, and correlation curves have been plotted.

Water Sorption by Polyheteroarylenes.

The sorption-diffusion characteristics of rigid-chain glassy polymers based on polyheteroarylenes (PHAs) have been studied in a wide interval of relative humidity and temperatures of thermal treatment of the polymer sorbents. Experimental data on water vapor sorption for polynaphthoyleneimidobenzimidazole (PNIB) and its copolymers with different chemical nature have been obtained. Water diffusion coefficients have been calculated, and parameters of their concentration and temperature dependences have been determined.

The Influence of Substituents in Phosphazene Catalyst-Flame Retardant on the Thermochemistry of Benzoxazine Curing.

This work is devoted to the influence of phosphazene modifiers with different substituents on the curing process, thermal properties and flammability of benzoxazine resin. Novel catalysts with m-toluidine substituents were introduced. The catalytic activity of studied phosphazene compounds decreased in the row: hexachlorocyclotriphosphazene (HCP) > tetra m-toluidine substituted phosphazene PN-mt (4) > hexa m-toluidine substituted phosphazene PN-mt (6) > hexaphenoxycyclotriphosphazene (HPP), where HPP is totally inactive.

Free Volume and Water Sorption by Cellulose Esters.

The results ofthe sorption properties of cellulose acetate (CA) with different degrees of substitution (SD) are summarised. It has been shown that the sorption capacity of CA in water vapour decreases naturally with increasing content of acetate groups in monomeric units of cellulose ethers. The experimental isotherms are analysed according to the double sorption model.

Phase Equilibrium and Interdiffusion in Blends of Polystyrene with Polyacrylates.

The solubility and interdiffusion of polystyrene (PS) with polymethyl acrylate (PMA), polyethyl acrylate (PEA), polybutyl acrylate (PBA), and polyethylhexyl acrylate (PEHA) have been studied by the optical interferometry method. Phase state diagrams are plotted. It is shown that they are characterized by the upper critical solution temperatures (UCST), which are localized in the temperature range above 450 K.

Phase Equilibrium, Morphology, and Physico-Mechanics in Epoxy-Thermoplastic Mixtures with Upper and Lower Critical Solution Temperatures.

The mutual solubility of epoxy oligomer with polysulfone (PSU) and polyethersulfone (PES) was studied by optical interferometry. Additionally, phase diagrams (PDs) were plotted and their evolution during the curing process was shown. The phase structures of modified hardened systems, as well as their tensile strengths, elastic moduli, and crack resistance, have been studied by scanning electron microscopy and physico-mechanical techniques.

Phase Equilibrium and Interdiffusion in Poly(Vinyl Methyl Ether)-Water System.

The phase state diagram of the poly(vinyl methyl ether)-water system in a wide concentration range was obtained by the optical interferometry method. It was shown that this system was characterized by a complicated phase equilibrium with two lower critical solution temperatures, one of which was located in the concentrated region at 21 °C, and the other one in the region of a dilute solution at 31 °C. In the framework of the Flory-Huggins theory, pair interaction parameters were calculated for different parts of the binodal curves, and an attempt was made to reverse simulate the diagram in different conditions.