Partially fluorinated sulfonated poly(arylene sulfone)s blended with polybenzimidazole

A partially fluorinated and sulfonated poly(arylene sulfone) (SPSO) was successfully synthesized via nucleophilic polycondensation of 2,2‐bis(4‐fluorophenyl)hexafluoro‐propane with 4,4′‐thiobisbenzenethiol (TBBT). In a second step, the prepared poly(arylene sulfide) was oxidized to SPSO. The polymer was blended with the polybenzimidazole PBIOO^® to obtain a mechanically stable membrane. This film was compared with other polymer blends, which were synthesized in our group in the last years. We were especially interested in the influence of different bridging groups such as ether, ketone, and sulfone groups. The affect on properties such as water uptake (WU), thermal stability, proton conductivity, and oxidative stability were analyzed in this work. Additionally, the blend membranes were characterized by gel permeation chromatography. The novel SPSO blend shows a high molecular weight, and its blend membrane with PBIOO has an excellent onset of ? SO₃H group splitting‐off temperature (T_onset) of 334 °C. The proton conductivity amounts to 0.11 S cm^?1, and the water uptake reaches 30%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Energy transfer in double plate system dynamics

The study of energy transfer between coupled subsystems in a hybrid system is very important for applications. This paper presents an analytical analysis of energy transfer between plates of a visco-elastically connected double-plate system in free transversal vibrations. The analytical analysis shows that the visco-elastic connection between plates is responsible for the appearance of two-frequency regime in the time function, which corresponds to one eigen amplitude function of one mode, and also that time functions of different vibration modes are uncoupled, but energy transfer between plates in one eigen mode appears. It was shown for each shape of vibrations. Series of the two Lyapunov exponents corresponding to the one eigen amplitude mode are expressed by using the energy of the corresponding eigen amplitude time component.     

Transversal forced vibrations of an axially moving sandwich belt system

Based on the author’s previously published results for transversal free vibrations of axially moving sandwich belts described by coupled partial differential equations, which are derived and analytically solved, this paper contains new analytical results, for forced vibrations of the same system excited by transversal external excitation. The transversal forced vibrations of the axially moving sandwich belts are described by the coupled partial nonhomogeneous differential equations. The partial differential equations are analytically solved. Bernoulli’s method of particular integrals and Lagrange’s method of the variations of the constants are used.     

SEM/EDS investigation of one-step flame sprayed and fused Ni-based self-fluxing alloy coatings on steel substrates

Abstract

This study presents the results of light optical and scanning electron microscopy as well as energy dispersive spectroscopy investigation of the Ni-based self-fluxing alloys (NiCrBSi, NiCrWBSi and NiCrBSi + WC) deposited on steel substrates (heat treated carbon steel C45, heat treated low-alloyed steel 42CrMo4 and austenitic stainless steel X6CrNiMo18-10-2) by one-step flame spraying and fusing process. The microstructure of coatings and coating/substrate interface but also the effects of deposition technology on the heat-treated steel substrates which have frequently been used in practice were investigated. The influence of the sample size on the microstructure was also discussed. A proof is given of the change in the structure of coating, coating/substrate interface and substrate due to high fusing temperature, depending on type of steel substrate (and relating thermal properties), coating thickness but also on dimensions of the sample.     

Double plate system with a discontinuity in the elastic bonding layer

The double plate system with a discontinuity in the elastic bonding layer of Winker type is studied in this paper. When the discontinuity is small, it can be taken as an interface crack between the bi-materials or two bodies (plates or beams). By comparison between the number of multifrequencies of analytical solutions of the double plate system free transversal vibrations for the case when the system is with and without discontinuity in elastic layer we obtain a theory for experimental vibration method for identification of the presence of an interface crack in the double plate system. The analytical analysis of free transversal vibrations of an elastically connected double plate systems with discontinuity in the elastic layer of Winkler type is presented. The analytical solutions of the coupled partial differential equations for dynamical free and forced vibration processes are obtained by using method of Bernoulli’s particular integral and Lagrange’s method of variation constants. It is shown that one mode vibration corresponds an infinite or finite multi-frequency regime for free and forced vibrations induced by initial conditions and one-frequency or corresponding number of multi-frequency regime depending on external excitations. It is shown for every shape of vibrations. The analytical solutions show that the discontinuity affects the appearance of multi-frequency regime of time function corresponding to one eigen amplitude function of one mode, and also that time functions of different vibration basic modes are coupled. From final expression we can separate the new generalized eigen amplitude functions with corresponding time eigen functions of one frequency and multi-frequency regime of vibrations. The English text was polished by Keren Wang.     

Energy interaction between linear and nonlinear oscillators (energy transfer through the subsystems in a hybrid system)

The analysis of the energy transfer between subsystems coupled in a hybrid system is an urgent problem for various applications. We present an analytic investigation of the energy transfer between linear and nonlinear oscillators for the case of free vibrations when the oscillators are statically or dynamically connected into a double-oscillator system and regarded as two new hybrid systems, each with two degrees of freedom. The analytic analysis shows that the elastic connection between the oscillators leads to the appearance of a two-frequency-like mode of the time function and that the energy transfer between the subsystems indeed exists. In addition, the dynamical linear constraint between the oscillators, each with one degree of freedom, coupled into the hybrid system changes the dynamics from single-frequency modes into two-frequency-like modes. The dynamical constraint, as a connection between the subsystems, is realized by a rolling element with inertial properties. In this case, the analytic analysis of the energy transfer between linear and nonlinear oscillators for free vibrations is also performed. The two Lyapunov exponents corresponding to each of the two eigenmodes are expressed via the energy of the corresponding eigentime components. Published in Ukrains'kyi Matematychnyi Zhurnal, Vol. 60, No. 6, pp. 796–814, June, 2008.     

Non-linear dynamics of the sandwich double circular plate system

Multi-frequency vibrations of a system of two isotropic circular plates interconnected by a visco-elastic layer that has non-linear characteristics are considered. The considered physical system should be of interest to many researches from mechanical and civil engineering. The first asymptotic approximation of the solutions describing stationary and no stationary behavior, in the regions around the two coupled resonances, is the principal result of the authors. A series of the amplitude-frequency and phase-frequency curves of the two frequency like vibration regimes are presented. That curves present the evolution of the first asymptotic approximation of solutions for different non-linear harmonics obtained by changing external excitation frequencies through discrete as well as continuous values. System of the partial differential equations of the transversal oscillations of the sandwich double circular plate system with visco-non-linear elastic layer, excited by external, distributed, along plate surfaces, excitation are derived and approximately solved for various initial conditions and external excitation properties. System of differential equations of the first order with respect to the amplitudes and the corresponding number of the phases in the first asymptotic averaged approximation are derived for different corresponding multi-frequency non-linear vibration regimes. These equations are analytically and numerically considered in the light of the stationary and no stationary resonant regimes, as well as the multi-non-linear free and forced mode mutual interactions, number of the resonant jumps.     

Synthesis of 1‐nonanoyl/octadecanoyl‐4‐substituted thiosemicarbazides and substituted 1,2,4‐trizoles as biological active compounds

4‐Alkyl/aryl‐5‐nonanoyl/octadecanoyl‐2,4‐dihydro‐3H‐1,2,4‐triazoline‐3‐thiones were synthesized as potential antimicrobial agents. The course of synthesis included the reaction of nonanoyl/octadecanoyl hydrazines with selected alkyl/aryl isothiocyanates. The prepared thiosemicarbazides gave by cyclization the required 1,2,4‐triazoles. A number of synthesized compounds were subjected to in vitro testing against two gram‐positive, two gram‐negative bacteria and two fungi.     

Nichtsteroidale entzündungshemmer. 13. Bis-(4-methoxyphenyl)-2-arylthiopyrimidine

The synthesis of 4,5-bis-(4-methoxyphenyl)-2-arylthio- and 4,6-bis-(4-methoxyphenyl)-2-arylthiopyrimidines are described. The phenylthio, 4-fluorophenylthio-, 2-thienylthio derivatives were prepared.