438 research outputs found
In-situ interfacial approaches on chemisorption and stability of buried metal oxide-polymer interfaces
No full textUntil today, interfacial bond formation and degradation between polymer coatings and metal substrates is still far from fully understood, whilst it is a limiting factor for the durability of metal-polymer hybrid systems. To improve the corrosion resistance and adhesion properties of metal substrates, a chemical surface treatment is applied prior to painting. However, due to ecological and health related issues, traditional well established surface treatments containing hexavalent chromate or high phosphate loads are being replaced by a new generation of ecologically-justified surface treatments. This comes with the need of gaining fundamental insights on the impact of substrate and pretreatment variations on the (chemical) adhesion of polymers to guarantee the lifetime of newly developed metal-polymer hybrid systems. A challenge in this regard is the hardly accessible buried interface, which until today requires the use of model systems when using non-destructive surface sensitive techniques. Yet, industrial metal-polymer hybrid systems are typically highly heterogeneous, creating a distinct gap between model and industrial systems. This dissertation aims to close this gap starting from simplified model systems to which complexity is gradually added. This has been done using the thin organic film approach on one hand, and the thin (thermally vaporized) metal substrate approach on the other hand, allowing non-destructive access of the metal-polymer interface from the polymer side and metal side, respectively. Complementary use of both approaches allows systematically comparison of model systems to industrially relevant paint and metal substrates.(OLD) MSE-
Scientific school of doctor of biological sciences professor L.I. Rubtsov
No full textObjective – to explore the scientific school of the famous landscape architect, dendrologist, doctor of biological sciences professor Leonid Ivanovich Rubtsov.
Material and methods. Creative biographies of L.I. Rubtsov’s post graduate students have been analyzed. The historical- scientific method and method of interviews were used.
Results. The theoretical scientific developments of L.I. Rubtsov, set out in unique monographs, and his ideas are implemented practically during the construction a number of botanical gardens and parks were investigated. Professor Rubtsov worked fruitfully for 50 years in the field of dendrology and green building. In M.M. Gryshko National Botanical Garden of the NAS of Ukraine Leonid Ivanovich was the author and the head of the work on the arboretum creation. In 1972 the Botanical Garden was granted the status of a monument of landscape art of national importance. This became possible thanks to works of L.I. Rubtsov. His knowledge and great experience he passed on to his students, who eventually became good experts in dendrology and landscape architects. Professor L.I. Rubtsov was the head of 8 post graduate students (Candidates of Sciences): namely 3 Candidates of Architecture (I.D. Rodichkin, V.G. Maevskaya, V.I. Meshkova) and 5 Candidates of Biological Sciences (M.I. Orlov, Yu.K. Kirychek, M.F. Kaplunenko, B.K. Gryshko-Bogmenko, N.F. Kolybina).
Conclusions. Erudition, a wide range of interests and style of work of Leonid Ivanovich were of decisive importance for attracting young talents and for many years determined their creative ways. Scientific works of L.I. Rubtsov, especially monographs, reference books and manuals are still indispensable benefits for many specialists in the field of landscape architecture and decorative gardening
Arsenic migration and water uptake in multilayer painting systems
No full textOrpiment and realgar are yellow and red arsenic sulphide pigments that have been used since antiquity in works of art until the 19thcentury, when their use was restricted due to their toxicity. With time, these pigments degrade to form colourless arsenic oxide. Different oxidation states of arsenic (+3 and +5) in the degradation products have been recently found. Moreover, they have been identified throughout the whole painting layout from the panel until the varnish, suggesting the migration of degradation products through the paint layers. Besides changing the aspect, they might change the stability of the painting or painted object. Furthermore, they might represent a potential hazard for conservators when dealing with the work of art. Since a painting is in equilibrium with its environment, there is always water in motion inside the painting. It is therefore believed that the degradation products are migrating via water. However, the migration mechanism is still not well understood. This thesis aims to provide a better insight into the diffusion process of arsenites (As+3) and arsenates (As+5) in materials commonly found in paintings. For this, two different approaches were followed: In one hand, light aged painting reconstructions were analysed with FTIR microscopy and SEM-EDS to asses the effect of different grounds and relative humidity on the migration of arsenic. In all the samples, degradation products were found in the orpiment layer based on the As-O vibration, detected with FTIR microscopy. It was possible to identify arsenic in the ground layer close to the orpiment-ground interface for all samples with both techniques. However, due to the low intensity and the proximity to the interface of the arsenic found in the grounds, no conclusions could be drawn about its migration. On the other hand, in-situ ATR-FTIR spectroscopy and EIS measurements were performed on a set of samples to analyse the water, arsenates and arsenites diffusion through oil and two varnishes (dammar and mastic). The diffusion coefficients of water in oil, dammar and mastic were determined with both techniques. It was found that the water diffuses faster in oil than in the two varnishes. Despite being similar, mastic was found to be less stable than dammar since a decrease in its barrier properties with time was found. The diffusion of arsenates and arsenites in dammar and mastic was studied by EIS and the diffusion coefficients were calculated for the first time. It was found that the diffusion of arsenites in the coatings is faster than arsenates, which is in accordance to the diffusion of these species in water. EIS resulted in a promising technique in the study of diffusion of ions in coatings. Although further research is needed to fully understand the migration mechanism of arsenic in painting systems, this thesis provides a useful insight and a methodology with which the water and ion transport in coatings can be studied
Probing the formation and degradation of chemical interactions from model molecule/metal oxide to buried polymer/metal oxide interfaces
No full textThe mechanisms governing coating/metal oxide delamination are not fully understood, although adhesive interactions at the interface are considered to be an important prerequisite for excellent durability. This review aims to better understand the formation and degradation of these interactions. Developments in adhesion science made it clear that physical and chemical interfacial interactions are key factors in hybrid structure durability. However, it is very challenging to get information directly from the hidden solid/solid interface. This review highlights approaches that allow the (in situ) investigation of the formation and degradation of molecular interactions at the interface under (near-)realistic conditions. Over time, hybrid interfaces tend to degrade when exposed to environmental conditions. The culprits are predominantly water, oxygen, and ion diffusion resulting in bond breakage due to changing acid–base properties or leading to the onset of corrosive de-adhesion processes. Therefore, a thorough understanding on local bond interactions is required, which will lead to a prolonged durability of hybrid systems under realistic environments.(OLD) MSE-
Effect of zirconium-based conversion treatments of zinc, aluminium and magnesium on the chemisorption of ester-functionalized molecules
No full textThe effect of zirconium-based conversion of thermally vaporized zinc, aluminium and magnesium on the chemisorption of dimethylsuccinate was studied using attenuated total reflection – Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. Two competing chemisorption mechanisms contribute to interfacial bond formation. Hydrogen interactions on one hand were shown to occur between metal hydroxides and non-hydrolysed ester-groups of the molecule. On the other hand, both native and zirconium-treated substrates were shown to form interfacial carboxylate bonds with dimethylsuccinate, evidencing their capability of hydrolysing ester groups towards more reactive acid groups. Both interactions were shown to correlate to the metal oxide acid-base properties.(OLD) MSE-
Studying Chemisorption at Metal-Polymer Interfaces by Complementary Use of Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) in the Kretschmann Geometry and Visible-Infrared Sum-Frequency Generation Spectroscopy (SFG)
No full textThe molecular configuration and chemistry at the zinc/zinc oxide-polyester interface were studied by using two complementary spectroscopic techniques: attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and sum-frequency generation (SFG) spectroscopy. It was shown that ATR-FTIR should be considered as a (3D) interphase-sensitive technique with probing depths of 250-400 nm in the headgroup region (2000-1200 cm-1). On the other hand, SFG is known to be a (2D) interface-sensitive technique. The ATR-FTIR measurements showed that carboxylate groups are formed within the near-interface region of the polyester phase. SFG measurements showed that the carboxylic acid groups are stable at the polymer-zinc/zinc oxide interface. In addition, in situ ATR-FTIR and SFG measurements have been conducted when exposing the polyester-zinc/zinc oxide system to D2O. The exposure to D2O is observed to lead to an additional conversion of ester and carboxylic acid groups to carboxylate groups. The comparison of the SFG and ATR-FTIR measurements shows that this conversion occurs much slower at the polyester-zinc/zinc oxide interface than in the bulk of the polyester. Finally, the strengths and limitations as well as the complementarity of both techniques are discussed.(OLD) MSE-
In situ methanol adsorption on aluminum oxide monitored by a combined ORP-EIS and ATR-FTIR Kretschmann setup
No full textA common approach to investigate chemical interactions at the polymer/metal oxide interface is by monitoring ultrathin polymer films onto a metal oxide substrate by a variety of surface analysis techniques. The deposition of this nanometer-thin overlayer is frequently carried out by reactive adsorption from dilute polymer solutions. However, the influence of the solvent on the metal oxide chemistry is seldom taken into account in interface studies. The overall amount of available adsorption sites on the metal oxide surface might decrease due to competing adsorption of the solvent and the polymer adsorbate. Therefore, in this work, the adsorption of a common organic solvent (methanol) onto a physical vapor-deposited aluminum oxide surface is monitored in situ by an integrated attenuated total reflectance Fourier transform infrared spectroscopy in the Kretschmann geometry and odd random phase multisine electrochemical impedance spectroscopy system. It is shown that methanol immediately physisorbs onto the aluminum oxide surface and replaces the initial adventitious carbon layer. This process is followed by methanol chemisorbing onto the oxide surface to form methoxide species at the liquid/solid interface. Additionally, chemisorption is validated ex situ by X-ray photoelectron spectroscopy.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.(OLD) MSE-
Numerical stability for velocity-based 2-phase formulation for geotechnical dynamic analysis
No full textAs a master student in AppliedMathematics at the Delft University of Technology I am highly educated in Numerical Analysis. My interest in this field even mademe choose elective courses such as Advanced Numerical Methods, Applied Finite Elements and Computational Fluid Dynamics. In my search for a challenging graduationproject I chose a research proposal on the material point method, an extension of the finite element method that is well-suited for problems involving large deformations. The proposal met al my personal requirements, since it contained a mathematical basis I am already familiar with and the opportunity to gain knowledge about a relatively new numerical method. Furthermore, it included an internship at DeltaresDelft Institute of Applied MathematicsElectrical Engineering, Mathematics and Computer Scienc
Bereiding van witte phosphor: Verslag behorende bij het eerste gedeelte van het fabrieksschema voor de bereiding van rode phosphor
No full textDocument(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science
Modularization and Specification of Service-Oriented Systems
No full textDepartment of Information SystemsElectrical Engineering, Mathematics and Computer Scienc
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