Action Of Shear Deformation Research Articles

Investigation of the Influence of UV Radiation on Compositions of Polylactide with Graphite Nanoplates

Composites of polyether polylactide (PLA) synthesized from natural raw materials with graphite nanoplates (GNP), which represent a new type of composite materials based on biodegradable polymers, were obtained by solid-phase method under the action of shear deformations. The porosity of composites was evaluated and their electrical and mechanical properties were studied. The effect of UV radiation on the molecular weight and molecular weight distribution of PLA in PLA-GNP composites of different compositions was investigated using the method of excision chromatography (EC), and the effect of the GNP nanofiller content on the change of their mechanical characteristics in the process of radiation was shown.

Physico-chemical and rheological properties of meat pates with corn starch suspensions prepared on electrochemically activated water

Introduction. The aim of the study was to determine the influence of electrochemically activated water application on the rheological properties of corn starch suspensions and pates prepared with them. Materials and methods. Corn starch suspensions were prepared on artesian water, which was activated by electrochemical treatment on a diaphragm electrolyzer. Physico-chemical characteristics of electrochemically activated water were determined using a Palintest 7500 photometer. Morphological studies of starch granules were carried out by scanning electron microscopy, and granulometric composition was determined by laser diffraction method. The rheological indicatorss of starch suspensions and pates were studied using a Kinexus Pro+ rheometer. Results and discussion. The physico-chemical characteristics of electrochemically activated water except pH met the requirements of the European Parliament and Council Directive on the quality of water intended for human consumption. The water absorption capacity of starch when preparing its suspensions on a catholyte (obtained by passing a direct electric current through water in the cathode chamber of an electrolyzer) decreased by 26%, and when prepared on an anolyte (obtained in the process of water oxidation reactions on the anode) increased by 18%. The moisture holding capacity of hydrated starch decreased by 10% when using catholyte, and increased by 36% when using anolyte. Electrochemically activated water had a significant effect on the rheological characteristics of starch suspensions: with an increase in the percentage of complex shear strain, the shear stress increased proportionally for samples of suspensions made on electrochemically activated water. The viscoelastic properties of starch suspensions prepared using electrochemically activated water both at 25 ℃ and at 68 ℃ tended towards an ideally elastic gel, that is, they had more elastic structure than the control samples. Under the action of shear deformation, the elastic properties were lost, while the suspensions acquired viscosity (phase angle values increased). The maximum value of the moisture binding capacity of pates was observed when using a starch suspension prepared on anolyte. The best values of rheological characteristics of pates were obtained when using starch suspension with 2% starch prepared on anolyte. Conclusions. Electrochemically activated water had a significant effect on the physicochemical and rheological properties of semi-finished products, in particular corn starch suspensions, and pates prepared with them, and contributed to better structuring of the studied food systems.

Bonding mechanism and preparation process of titanium/iron composite thin sheet by non-vacuum rolling

As a new type of layered metal composite sheet, titanium/iron composite thin sheet has attracted much attention because it can meet the dual requirements of the environment and material properties. This paper reports a non-vacuum rolling method that is more suitable for preparing titanium/iron composite thin sheet in industrial production. Herein, the bonding mechanism of the layered metal composite sheet was elucidated by analyzing the forces on the sheets during the non-vacuum rolling process then it was applied to explain the influence mechanism of the rolling reduction rate on interfacial bonding properties. The titanium/iron composite thin sheet was prepared by non-vacuum rolling with a 65% rolling reduction rate, and the interfacial microstructure was studied to verify the accuracy of theoretical judgments. The results show that a shear deformation zone exists at the interface of the layered metal composite sheet in the rolling process. In this zone, the oxide film on the interface breaks, and the exposed fresh metal undergoes metallurgical bonding under the action of radial rolling force to form a composite interface. With the increase of rolling reduction rate, the range of the shear deformation zone expands, and the radial rolling force acting on the interface increase, which is the main reason for the improvement of the rolling reduction rate on the bonding effect. Shear deformation caused vast dislocations in the interface microstructure of composite sheet. The texture of the titanium layer has a certain width under the action of shear deformation. The texture of the iron layer is mainly α-fiber, caused by shear deformation. Moreover, broken oxide films and diffusion layers of titanium and iron elements were observed at the interface.

First-principles calculation to investigate the influence of shear deformation on the electronic structure and optical properties of hydrogenated silicene

The CASTEP program based on density functional theory was used to study the effect of shear deformation on the structure, electronic and optical properties of hydrogenated silicene. The calculation results show that the hydrogenated silicene can still remain stable under the action of shear deformation. After the hydrogenation of silicene, the forbidden band width increases to 2.204 eV, and the electrical conductivity is significantly improved. Shear deformation significantly affects the energy band structure characteristics of hydrogenated silicene. The resulting band gap gradually decreases as the deformation increases. The shear deformation causes the red shift of the imaginary part of the dielectric function of the hydrogenated silicene to the direction of lower energy. Shear deformation improves the luminous efficiency of the system. The peak range of the reflection spectrum gradually widens with the increase of the deformation. These properties may be applied to optoelectronic devices in the future.

Preparation and Study of the Properties of Compositions Based on Crumb Rubber and Natural Polysaccharides

Crumb rubber compositions with starch and cellulose were obtained under the action of shear deformations in a closed type mixer (Brabender). It has been shown that the mechanical characteristics of both compositions differ slightly from each other. When the polysaccharide content in the mixture is increased, the elastic modulus grows and the strength and elongation at break are reduced. The addition of polyethylene glycol slightly affects the values of the mechanical parameters. After exposure of the samples in soil, an increase in mechanical characteristics, which is likely to be due to the occurrence of crosslinking of crumb rubber by radicals formed under the influence of the environment, is observed.

Interaction of edge dislocation with copper atoms in an aluminum crystal

In this work, the interaction of the moving edge dislocation with obstacles in form of copper atoms is studied using the molecular dynamics simulations. The samples are aluminum monocrystals of 52 × 60 × 15 nm3 with axes oriented along directions [110], [111], [112]. The structure of copper solid solution is reproduced with following procedure: aluminum atoms are randomly selected and replaced by copper atoms. The concentration of copper atoms varies from 0.25% to 1%. The dislocation movement occurs under action of shear deformation. It is found that zones with a low concentration of copper atoms only slow down dislocation in an aluminum matrix, and the zones with a high local concentration of copper atoms not only produces stronger resistance to dislocation movement, but also they cause the change in the slip plane of the dislocation segment. When a significant part of a dislocation line moves to a neighboring slip plane, the complete transition of the dislocation to this slip plane can occur. It is also noted that such transitions of dislocation segments from one slip plane to another are accompanied by the formation of vacancies. Also the maximum value of the shear stress σxy is estimated-its value is approximately 250 MPa.

Kinetic aspects of concentration of solid nanoparticles at the interface in polystyrene–polyethylene mixtures

ABSTRACTThe effect of several mixing process parameters on the concentration of carbon black particles at the interface between the polymer components in polyethylene–polystyrene mixtures was studied. It was established that the process of particle transport from the polymer phase to the interface happens only under the action of shear deformation, but simultaneously acting shear stresses prevent particle concentration. The nanoparticle accumulation at the interface is determined not only by how favored this process is thermodynamically, but also by the parameters of the mixing process. The filler concentration at the interface is facilitated by a reduction in the shear stress, polymer viscosity, filler particle size, and preliminary injection of filler into the polymer component that is less effective at wetting the filler surface. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48585.

Dynamic Response of Flexible Wind Turbine Blade

Aiming at the non-stationary and stall flutter problems of wind turbine blade caused by transient load fluctuations, the dynamic properties of wind turbine were studied, the blade was simplify to a cantilever beam in case of the action of shear deformation and cross section rotating effect were considered in this analysis, equations of the blade were established based on D'Alemberts' principle and the principle of virtual displacement. The dynamic response of the wind turbine was solved by using the finite element method under the transient load environment. A 29.2 m rotor blade, previously reported in specialized literature, was chosen as a case study to validate dynamic behaviour predicted by a Timoshenko beam model. It is concluded that despite its simplicity, The cross-sectional shear-deformation has great influence on dynamic response of the blade.Dynamic model is sufficiently accurate to serve as a design tool for the recursive analyses required during design and optimization stages of wind turbines using only readily available computational tools. DOI: http://dx.doi.org/10.11591/telkomnika.v11i12.3329

Biodegradable blends based on chitin and chitosan: Production, structure, and properties

AbstractBlends based on LDPE and chitin or chitosan were prepared under high‐temperature shear deformations in a rotor disperser at different initial ratios of the components. Although one of the components is an infusible polymer (polysaccharide), the powder blends were obtained. The composition of the powder fractions was shown to be identical to the original blend composition. It was found that the addition of poly(ethylene oxide) to the mentioned blends improves the biodegradability of the polymer materials and extends their application areas. Using various physicochemical methods, the structural and morphological changes in the polymer compositions under the action of shear deformations were examined, the mechanical characteristics of prepared films were determined, and also the features of their bio‐, thermo‐, and photo‐oxidative degradation were studied. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Cellulose depolymerization to glucose and other water soluble polysaccharides by shear deformation and high pressure treatment.

The simultaneous action of shear deformation and high pressure (SDHP) creates changes in the structure of wood and its main components (cellulose, hemicelluloses, lignin). The formation of water and alkali soluble polysaccharides under SDHP action, proceeds in seconds in the solid state, without the use of any reagents and solvents. Therefore, SDHP seems to be a technologically safe method and friendly to the environment. The amorphization of cellulose crystallites and depolymerization of cellulose chains were observed under a wide range of pressures (1-6 GPa), both for cellulose samples and the cellulose part of wood. Similar depolymerization occurs in the hemicellulose part of wood. The decomposition of polysaccharides under SDHP causes the formation of the water soluble part, whose content increases with pressure and the applied shear deformation. A maximum solubility of 40% and 55% was registered at 6 GPa following treatment of cellulose and birch wood samples. A higher output in the case of wood can be explained by a specific role of lignin under SDHP, which acts as a 'grinding stone' during cellulose and hemicelluloses destruction. As shown by high-performance size exclusion chromatography, the water soluble fraction obtained from cellulose contained glucose (2.6%), cellobiose (9.6%), cellotriose (16.6%) and other higher water soluble oligomers (71%). Almost complete dissolution (98%) of the treated cellulose sample can be achieved by extraction with 10% NaOH solution. The SDHP treated birch wood was subjected to submerged fermentation (with Trichoderma viride), and a 13% output of proteins was obtained. In this case, the water soluble part played the role of the so called 'start sugars'.

Piezotunnel current in GaAs p-n junctions

A calculation is made of the sensitivity to shear deformations of the tunnel current in tunnel p-n junctions of gallium arsenide. The approximation of high hole energies (¦E-Ev¦≫δ) was used in the calculation, where δ is the energy splitting of the branches of light and heavy holes at the center of the Brillouin zone produced by the action of shear deformations. The effect of hydrostatic and uniaxial pressure on the tunnel current with the p-n junction oriented parallel to the (100) and (111) crystallographic planes was studied experimentally. Satisfactory agreement was obtained between the calculated and experimental values of the coefficients of the piezotunnel current.