scholarly journals Polimeryzacja aniliny w środowisku stałego pola magnetycznego

Polimery ◽  
2021 ◽  
Vol 66 (7-8) ◽  
Author(s):  
Ewa Miękoś ◽  
Bronisław Samujło ◽  
Marek Zieliński ◽  
Dariusz Sroczyński
Keyword(s):  
Electrochemical Polymerization ◽  
External Action ◽  
Electrochemical Reactions ◽  
Electrochemical Preparation ◽  
Electrode Processes ◽  
Degree Of Oxidation ◽  
Magnetohydrodynamic Effect ◽  
The Impact ◽  
Kinetics Of ◽  
Aniline Polymerization

Polyaniline is an example of an electronically conducting polymer. During the oxidation of the polymer, positive charges appear in its structure, which must be compensated for e.g. by the presence of anions in the polymer layer. The form of polyaniline depends on both the degree of oxidation and the degree of protonation of the polymer, i.e. the pH of the solution. Due to the ease of electrochemical preparation of polyaniline, as well as the possibility of full control of the course of the process, the influence of the constant magnetic field (s.p.m.) on the reaction of its preparation was additionally investigated. The cyclic voltammetry (CV) method was used for this purpose. Aniline polymerization processes were carried out on platinum, plate electrodes, not insulated (A) and insulated on two different sides with Teflon, with surfaces directed parallel to the line of force of the s.p.m. (To beat). Research on the electrochemical preparation of polyaniline in s.p.m. allowed to conclude that the following factors affect the magnitude of the current in the tested process: (i) the magnitude of the magnetic induction vector B, (ii) the position of the electrode plane in relation to the direction of the vector B, (iii) the type of electrode (insulated on one side or not). Impact on the impact of s.p.m. the magnetic properties (e.g. paramagnetic, diamagnetic) of the particles participating in the electrochemical reaction, as well as their charge (+/-), also had an effect on the electrochemical polymerization processes. Based on the experimental results, the mechanism of the influence of s.p.m. was proposed. on the tested electrochemical reactions. This mechanism was based, inter alia, on the formation of the magnetohydrodynamic effect (MHD), which causes a change in the speed of transport of the reacting substances to the electrode, the magnetohydrodynamic movement of the electrolyte and the change in the kinetics of electrode processes. For the tested process, changes in the rate constants of electrochemical reactions (ks) as a result of external action of s.p.m. were around 30%.

Electrode kinetics

1981 ◽  
Vol 302 (1468) ◽  
pp. 221-235 ◽  
Keyword(s):  
Charge Transfer ◽  
Modified Electrodes ◽  
Packed Bed ◽  
Electrochemical Reactions ◽  
Electrode Kinetics ◽  
Electrode Processes ◽  
Redox Catalyst ◽  
Packed Bed Electrode ◽  
Modified Layer ◽  
Kinetics Of

An electrode is an ideal catalyst in that the potential difference at the electrodesolution interface controls both the thermodynamics and the kinetics of the electrochemical reactions. However, the kinetics of electrode processes are relatively unselective. Greater selectivity can be achieved by the use of modified electrodes in which a redox catalyst is attached to the electrode surface. The kinetics of charge transfer in the modified layer are discussed in this paper. Another major problem is that the reactant must find the electrode. High conversions can be achieved by using a packed bed electrode. Results are presented showing how the performance of this type of electrode can be improved by using a graded bed rather than a uniform bed.

scholarly journals Ice Coverage Induced by Depositing a Water Drop onto the Supercooled Substrate at Extreme Low Vapor Pressure

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 691
Author(s):  
Yugang Zhao ◽  
Zichao Zuo ◽  
Haibo Tang ◽  
Xin Zhang
Keyword(s):  
Vapor Pressure ◽  
Substrate Temperature ◽  
Water Drop ◽  
Industrial Processes ◽  
Aircraft Icing ◽  
Ice Coverage ◽  
Fundamental Understanding ◽  
Order Of Magnitude ◽  
The Impact ◽  
Kinetics Of

Icing/snowing/frosting is ubiquitous in nature and industrial processes, and the accretion of ice mostly leads to catastrophic consequences. The existing understanding of icing is still limited, particularly for aircraft icing, where direct observation of the freezing dynamics is inaccessible. In this work, we investigate experimentally the impact and freezing of a water drop onto the supercooled substrate at extremely low vapor pressure, to mimic an aircraft passing through clouds at a relatively high altitude, engendering icing upon collisions with pendant drops. Special attention is focused on the ice coverage induced by an impinging drop, from the perimeter pointing outward along the radial direction. We observed two freezing regimes: (I) spread-recoil-freeze at the substrate temperature of Ts = −15.4 ± 0.2 °C and (II) spread (incomplete)-freeze at the substrate temperature of Ts = −22.1 ± 0.2 °C. The ice coverage is approximately one order of magnitude larger than the frozen drop itself, and counterintuitively, larger supercooling yields smaller ice coverage in the range of interest. We attribute the variation of ice coverage to the kinetics of vapor diffusion in the two regimes. This fundamental understanding benefits the design of new anti-icing technologies for aircraft.

scholarly journals Morphology and crystallization kinetics of Rubber-modified Nylon 6 Prepared by Anionic In-situ Polymerization

2020 ◽  
Vol 27 (1) ◽  
pp. 204-215
Author(s):  
Hongkai Zhao ◽  
Dengchao Zhang ◽  
Yingshuang Li
Keyword(s):  
Crystallization Kinetics ◽  
In Situ Polymerization ◽  
Good Description ◽  
Nylon 6 ◽  
Avrami Equation ◽  
Infrared Analysis ◽  
Chain Segment ◽  
The Impact ◽  
Kinetics Of

AbstractIn this work, we modified nylon 6 with liquid rubber by in-situ polymerization. The infrared analysis suggested that HDI urea diketone is successfully blocked by caprolactam after grafting on hydroxyl of HTPB, and the rubber-modified nylon copolymer is generated by the anionic polymerization. The impact section analysis indicated the rubber-modified nylon 6 resin exhibited an alpha crystal form.With an increase in the rubber content, nylon 6 was more likely to generate stable α crystal. Avrami equation was a good description of the non-isothermal crystallization kinetics of nylon-6 and rubber-modified nylon-6 resin. Moreover, it is found that the initial crystallization temperature of nylon-6 chain segment decreased due to the flexible rubber chain segment. n value of rubber-modified nylon-6 indicated that its growth was the coexistence of two-dimensional discoid and three-dimensional spherulite growth. Finally, the addition of the rubber accelerated the crystallization rate of nylon 6.

scholarly journals Single entity electrochemistry and the electron transfer kinetics of hydrazine oxidation

Nano Research ◽  
2021 ◽  
Author(s):  
Ruiyang Miao ◽  
Lidong Shao ◽  
Richard G. Compton
Keyword(s):  
Electron Transfer ◽  
Bulk Solution ◽  
Relative Contribution ◽  
Rate Determining Step ◽  
Multistep Process ◽  
Ph Range ◽  
Electro Catalytic Oxidation ◽  
Single Particle Impact ◽  
The Impact ◽  
Kinetics Of

AbstractThe mechanism and kinetics of the electro-catalytic oxidation of hydrazine by graphene oxide platelets randomly decorated with palladium nanoparticles are deduced using single particle impact electrochemical measurements in buffered aqueous solutions across the pH range 2–11. Both hydrazine, N2H4, and protonated hydrazine N2H5+ are shown to be electroactive following Butler-Volmer kinetics, of which the relative contribution is strongly pH-dependent. The negligible interconversion between N2H4 and N2H5+ due to the sufficiently short timescale of the impact voltammetry, allows the analysis of the two electron transfer rates from impact signals thus reflecting the composition of the bulk solution at the pH in question. In this way the rate determining step in the oxidation of each specie is deduced to be a one electron step in which no protons are released and so likely corresponds to the initial formation of a very short-lived radical cation either in solution or adsorbed on the platelet. Overall the work establishes a generic method for the elucidation of the rate determining electron transfer in a multistep process free from any complexity imposed by preceding or following chemical reactions which occur on the timescale of conventional voltammetry.

scholarly journals Dissecting the impact of target-binding kinetics of protein binders on tumor localization

iScience ◽  
2021 ◽  
Vol 24 (2) ◽  
pp. 102104
Author(s):  
Yunjin Song ◽  
Hoibin Jeong ◽  
Song-Rae Kim ◽  
Yiseul Ryu ◽  
Jonghwi Baek ◽  
...  
Keyword(s):  
Binding Kinetics ◽  
Tumor Localization ◽  
Protein Binders ◽  
Target Binding ◽  
The Impact ◽  
Kinetics Of

scholarly journals A Study of the Impact of Graphite on the Kinetics of SPS in Nano- and Submicron WC-10%Co Powder Compositions

Ceramics ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 331-363
Author(s):  
Eugeniy Lantcev ◽  
Aleksey Nokhrin ◽  
Nataliya Malekhonova ◽  
Maksim Boldin ◽  
Vladimir Chuvil'deev ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Phase ◽  
Continuous Heating ◽  
Diffusion Creep ◽  
Hard Alloys ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
The Impact ◽  
Kinetics Of

This study investigates the impact of carbon on the kinetics of the spark plasma sintering (SPS) of nano- and submicron powders WC-10wt.%Co. Carbon, in the form of graphite, was introduced into powders by mixing. The activation energy of solid-phase sintering was determined for the conditions of isothermal and continuous heating. It has been demonstrated that increasing the carbon content leads to a decrease in the fraction of η-phase particles and a shift of the shrinkage curve towards lower heating temperatures. It has been established that increasing the graphite content in nano- and submicron powders has no significant effect on the SPS activation energy for “mid-range” heating temperatures, QS(I). The value of QS(I) is close to the activation energy of grain-boundary diffusion in cobalt. It has been demonstrated that increasing the content of graphite leads to a significant decrease in the SPS activation energy, QS(II), for “higher-range” heating temperatures due to lower concentration of tungsten atoms in cobalt-based γ-phase. It has been established that the sintering kinetics of fine-grained WC-Co hard alloys is limited by the intensity of diffusion creep of cobalt (Coble creep).

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