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Erik Ruf Tim Naundorf Tom Seddig Helmut Kipphardt Wolfgang Maison 《Molecules (Basel, Switzerland)》2022,27(6)
Organic acids, typically derived from an oil-based value chain, are frequently used as corrosion inhibitors in industrial metal working fluids. The criteria for selection of these corrosion inhibitors have changed in the last decades, and are today not only performance-driven, but influenced by ecological considerations, toxicity and regulatory standards. We present scalable semisynthetic approaches to organic corrosion inhibitors based on phosphonic acids from renewable resources. They have been evaluated by chip filter assay, potentiodynamic polarization measurements, electrochemical impedance measurements and gravimetry for corrosion protection of iron and steel in an aqueous environment at slightly alkaline pH. The efficacy of several phosphonic acids tested was found to be strongly dependent on structural features influencing molecular self-assembly of protective layers, and the solubility of salts formed with di- and trivalent cations from the media or formed during corrosion. A carboxyphosphonic acid (derived from castor oil) was found to have remarkable anticorrosive effects in all media tested. We attribute the anticorrosion properties of this carboxyphosphonic acid to the formation of particularly stable protective layers on the metal surface. It might thus serve as a commercially attractive substitute for current acidic corrosion inhibitors, derived from renewable resources. 相似文献
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Ernst Helmut Brandt 《Pramana》2006,66(1):67-81
The properties of the ideal periodic vortex lattice in bulk superconductors and in films of any thickness can be calculated
from Ginzburg-Landau theory by an iteration method using Fourier series. The London theory yields general analytic expressions
for the magnetic field and energy of arbitrary arrangements of straight or curved vortex lines. The elasticity of the vortex
lattice is highly nonlocal. The magnetic response of superconductors of realistic shapes like thin and thick strips and disks
or thin rectangular plates or films, containing pinned vortices, can be computed within continuum theory by solving an integral
equation. A useful example is a thin square with a central hole and a radial slit, used as superconducting quantum interference
device (SQUID). 相似文献
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Viscoelastic properties of a silicone resin crosslinked at various extents were characterised by means of rheology. The influence of temperature on the viscoelastic properties of the material as-delivered and in a state pre-crosslinked approximately to the gel point has been investigated by dynamic-mechanical measurements. While the glass transition temperature is increased by the crosslinking, no changes of the free volume fraction at T g and its thermal expansion coefficient were observed. Taking the different glass transition temperatures into account, it could be shown that the corresponding WLF-parameters are the same. The molar mass and, hence, the viscosity of the material can be increased by a heat treatment. The dependence of the zero shear-rate viscosity on the weight average molar mass indicates that the existence of entanglements of the polymer molecules is not very probable. 相似文献
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Helmut Duddeck Rainer Lecht 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2-4):169-178
Abstract The syntheses of 16 phenyl- (1 and 3) and phenylthiophosphoryl (2) derivatives are described. The 13C and 17O NMR data sensitively reflect electron density changes in the phosphoryl substituents caused by pπ–dπ back-donation from X/Y to P. Taft constants σ1 and σR 0 were derived for 16 phosphoryl substituents. 相似文献
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