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Crack Arrest and Velocity Osciliations due to Local Fracture-Plasticity Effect in Polymers
Maksimov, I . L .,Svirina, J . V . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.3
The nonisothermal dynamics of the unstable crack growth in polymers is investigated. The system of general equations (the heat conductivity equation and the crack propagation equation) is formulated taking into account the near-crack-tip plasticity, the specific geometry of the specimen (Chevron) and real temperature dependences of the material parameters (flow stress, critical stress intensity factor, specific heat, etc.). Numerical analysis of general equations reveals the existence of the high-frequency oscillations of the crack velocity and the crack-tip temperature in the course of the crack propagation. The stage of the oscillational crack advance is completed by the arrest. The conditions of crack arrest are discussed.
Dislocation Pattern Formation in the Course of Plastic Deformation
Maksimov, I . L .,Sarafanov, G . F . 대한금속재료학회(대한금속학회) 1999 METALS AND MATERIALS International Vol.5 No.4
The self-consistent evolution of a two-dimensional screw dislocation ensemble is investigated in plastically deformed crystal. A generalized isotropical multicomponent model for dislocation dynamics is proposed. It is found that the intense relaxation process of the excess Burgers vector of the two-dimensional screw dislocat ensemble results in the establishment of an effective diffusion regime for average density ρ_s(r, t) evolution. In a two-component system this gives rise to mutual component interdiffusion, playing an important role in the nonlinear evolution stage. Two types of-spatial structures are found to emerge in the course of plastic deformation: i) a one-dimensional structure, which is established due to rivalry between unstable modes and results in the emergence of reorientation bands in the crystal; ii) a two-dimensional structure, which is established due to cooperation of the modes and is responsible for the hexagonal cell formation in the crystal. It is shown that for a sufficiently low strain level a hexagonal cellular structure is preferable.
Aleksei Maksimov,Alina Vagapova,Marianna Kutyreva,Gennadiy Kutyrev 한국고분자학회 2022 Macromolecular Research Vol.30 No.1
A new hybrid adsorbent has been synthesized by covalent linking of activated zeolite with hyperbranched polyester containing 8 terminal N-benzoylthiocarbamate groups. The structure of the polymer ligand was defined by IR, 1H and 13C NMR spectroscopy. The complexing properties of the adsorbent have been studied using the example of complexes with Cu(II) and Co(II) ions. It was proved by IR spectroscopy that N-benzoylthiocarbamate and toluylenecarbamate groups participate in complexation with metal ions. According to electron microscopy and porometry data, the average particle diameter of the adsorbent is 34.56 μm and the mesopore diameter is 4.19 nm. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have shown that the hybrid adsorbent is thermally stable up to 150℃. The sorption capacities of the adsorbent for Cu(II) and Co(II) ions are 31.92 and 17.7 g/kg. It was shown that the desorption process of metal ions from the complexes occurs in an acidic medium at pH 4 with the regeneration of the original adsorbent.
Temperature - Dependent Micro Crack Healing Process
Kitamura, Kaxuhiro,Maksimov, Igor L .,Nishioka, Kazumi 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.6
The crack healing process is studied theoretically on the basis of the extended the Thomson-Obreimoff model. The system free-energy F as a function of the crack length l and temperature T is calculated using the self-consistent Einstein model. It is found that with the temperature increase, the energy barrier becomes lower and even disappears at the $quot;healing$quot; temperature T=T_h. It is demonstrated that the crack-lattice trapping in the Obreimoff model is controlled by the free-energy barrier height OF(T). The latter exhibits the universal power-law behavior. On the basis of the results obtained, the crack healing time is evaluated.
Biodegradable all-polymer field-effect transistors printed on Mater-Bi
Stucchi Elena,Maksimovic Ksenija,Bertolacci Laura,Viola Fabrizio Antonio,Athanassiou Athanassia,Caironi Mario 한국정보디스플레이학회 2021 Journal of information display Vol.22 No.4
The growing demand of disposable electronics raises serious concerns for the corresponding increase in the amount of electronic waste, with severe environmental impact. Organic and flexible electronics have been proposed long ago as a more sustainable and energy-efficient technological platform with respect to established ones. Yet, such technology is leading to a drastic increase of plastic waste if common approaches for flexible substrates are followed. In this scenario, biodegradable solutions can significantly limit the environmental impact, actively contributing to eliminate the waste streams (plastic or electronic) associated with disposal of devices. However, achieving suitably scalable processes to pattern mechanically robust organic electronics onto largely available biodegradable substrates is still an open challenge. In this work, all-organic and highly flexible fieldeffect transistors, inkjet printed onto the biodegradable and compostable commercial substrate Mater-Bi, are demonstrated. Because of the thermal instability of Mater-Bi, no annealing steps are applied, producing devices with limited carrier mobility, yet showing correct n-type behavior and robustness to bending and crumpling. The degradation behavior of the final system shows unaltered biodegradability level according to ISO 14851. These results represent a promising step toward sustainable flexible and large-area electronics, combining energy and materials efficient processes with largely available biodegradable substrates.
Thermally Stimulated Crack Propagation in Viscous - Plastic Materials
Golubeva, N . G .,Maksimov, I . L . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.4
A self-consistent description of non-isothermal fracture in viscous-plastic materials is given taking into account the temperature dependence of Griffith surface energy. On the basis of the crack motion equation in such materials, combined with the nonequilibrium-thermodynamical analysis of the energy dissipation near the crack tip, different regimes of crack propagation are described. It is found that thermally stimulated crack propagation leads to the acceleration of total fracture advance. Specifically, the advancement time for the quasi-adiabatic fracture condition τ_(αδ) is appreciably smaller, than the analogous time for the isothermal regime τ_(1σ).
Features of Nickel Nanoparticles Structure Synthesized by the Spark Discharge Method
Rhee, C.K.,Maksimov, A.D.,Beketov, I.V.,Medvedev, A.I.,Murzakaev, A.M. The Korean Powder MetallurgyMaterials Institute 2020 한국분말재료학회지 (KPMI) Vol.27 No.6
Nickel nanopowders are obtained by the spark discharge method, which is based on the evaporation of the electrode surface under the action of the discharge current, followed by vapor condensation and the formation of nanoparticles. Nickel electrodes with a purity of 99.99% are used to synthesize the nickel nanoparticles in the setup. Nitrogen is used as the carrier gas with a purity of 99.998%. XRD, TEM, and EDX analyses of the nanopowders are performed. Moreover, HRTEM images with measured interplanar spacings are obtained. In the nickel nanopowder samples, a phase of approximately 90 wt% with an expanded crystal lattice of 6.5% on average is found. The results indicate an unusual process of nickel nanoparticle formation when the spark discharge method is employed.
Phase equilibria and thermodynamic properties in the o-dichlorobenzene - mdichlorobenzene system
Konstantin Samukov,Aleksey Maksimov,Ekaterina Belova,Mikhail Bubenchikov,Irina Uspenskaya 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12
Rankine cycle is widely used in industry to convert heat to work using a working fluid. A mixture of oandm-isomers of dichlorobenzene can act efficiently as a working fluid in the cycle. An equation of state (EoS) approachwas chosen to model vapor-liquid equilibria and phase properties in the system. The best results were achieved withTsai-Chen EoS. Experimental measurements of volumetric properties of mixtures and solid-liquid equilibria were performed. These data were correctly predicted within the ideal assumption. An enthalpy-pressure diagram for the odichlorobenzene- m-dichlorobenzene system was calculated using the resulting EoS.