Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"chromic acid"”.
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The kinetics of the chromic acid oxidation of acetaldehyde
… the reaction of the oxidation of acetaldehyde by chromic acid in aqueous medium has been studied in an attempt to extend the present knowledge of oxidation by chromic acid. In particular, these experiments were undertaken in order to see if there are any similarities between this reaction and the …
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Chromic acid anodized Ti-6Al-4V: its characterization and its single lap bond strength to heat resistant adhesives
… This work was conducted to identify chromic acid (CA) anodization and bond process conditions which produced durable, structural anodized Ti-6Al-4V/heat resistant single lap bonds and to understand why these conditions were necessary. A structural single lap bond was defined as a bond …
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The Thermal Stability of Anodic Oxide Coatings - Strength and Durability of Adhesively Bonded Ti-6Al-4V Alloy
The lap shear strength of chromic acid anodized, primed, Ti-6Al-4V alloy bonded with a high performance FM-5 polyimide adhesive has been investigated as a function of thermal treatment for selected times at various temperatures in air. The research findings indicate that the lap shear strength …
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Crystallization behavior of poly (p-phenylene sulfide): kinetics and morphology
… One technique was based on the partial attack of chromic acid solutions at high temperature (100°C), whereas the other used suspensions of anhydrous aluminum chloride at lower temperature (35°C). The aluminum chloride approach was shown to be more appropriate and successful in enhancing the fine …
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Interfacially polymerized thin film composite membranes on microporous polypropylene supports for reverse osmosis desalination
… by pre-wetting with acetone, then oxidized with chromic acid solution kept at 65 C. Next, the procedure to successfully coat the hydrophilized flat film membranes was implemented. Poly(ethyleneimine) (PEI) and isophthaloyl dichloride (IPD) were chosen as the reaction monomers for IP. Pressure …
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Oxidation of Ring-A Aromatic Steroids
… using either chromium trioxide-aqueous sulphuric acid-acetone or chromium trioxide-aqueous acetic acid mixtures. It was found that chromic acid oxidation of ring-A aromatic steroids substituted with a strong electron-donating group, gives rise to products with the site of oxidation being …
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Weathering of wood surfaces: characteristics, mechanisms, and prevention
… treating wood surfaces with aqueous solutions of chromic acid or ferric chloride, by treating with penetrating chemical agents such as trial, glycol and 1-octadecanol, or by coating with clear polymeric ultraviolet stabilizers such as homo- and copolymer of …
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Understanding non-precious metal catalysts for the oxygen reduction reaction and investigating corrosion and surface properties of carbon-doped aluminum alloys
… coating in which the Al parts are treated in chromic acid solutions to create a passivation layer. However, chromic acid is highly toxic and alternative strategies for corrosion protection are needed. One potential solution is the formation of “covetic” Al alloys by adding carbon to molten Al …
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Investigation of acid/base interactions in adhesion
The fundamental study of Lewis acid/base interactions presented in this dissertation demonstrates the role of these interactions in adhesive phenomena. The model systems investigated were representative of real substrates and soft, viscoelastic adhesives where, in one case, favorable acid/base …
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Studies in isothiazole chemistry: I. isothiazolo [5,4-b] pyridines. II. approaches to isothiazolynes
… expected isothiazolo[5,4-b] pyridine carboxylic acids and chromic acid oxidation resulted in cleavage of the isothiazole ring to give 2,3-disubstituted pyridines. Ethyl 4-hydroxy-3-methylisothiazolo[5,4-b] pyridine-5-earboxylabe was readily obtained by thermal cyclisation of the malonate from …
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The electrolytic production of lead chromate using periodically reversed direct current and superimposed alternating current on direct current
… 6.0, by adding a solution to 2.0 weight percent chromic acid, the purity of the product was increased. Electrolysis of the same bath using periodically reversed direct current yielded 4.53 grams of lead chromate per ampere-hour, the purity being 93.9 percent lead chromate. The time ratio was …
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Solvent resistant microporous/nanoporous polymeric hollow fiber and flat film membranes and their applications
… pre-wetting with acetone and treating with hot chromic acid solution. The introduced procedure of "modified IP" involved wetting next with the aqueous monomer solution followed by the organic monomer solution. Nanofiltration membranes were characterized using solutes, safranin 0 (MW 351) and …
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Durability of Polyimide Adhesives and Their Bonded Joints for High Temperature Applications
… Based on an extensive screening study, chromic acid anodization (CAA) was chosen as the standard pretreament for this research project. Double cantilever beam specimens (DCB) were then made and aged at 150° C, 177° C, and 204° C in three different environments; ambient atmospheric air …
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Colorimetric sensor arrays with a pre-oxidation method for gaseous analytes
… array. Oxidation byproducts (e.g., carboxylic acids, phenols, aldehydes, etc.) are reactive species that can be easily detected. Since each analyte produces different kinds of oxidation byproducts, the array gives a unique signature for a wide range of VOCs. The identification and …
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Durability of Polyimide/Titanium Adhesive Bonds: An Interphase Investigation
… be the case with a polyimide adhesive bonded to chromic acid anodized (CAA) Ti-6Al-4V. The objective of the current research has been twofold: 1) to investigate the effect of thermal aging on the interphase region of polyimide/titanium adhesive joints, and 2) to evaluate the method used in the …
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Investigation of electroless nickel undercoat for duplex nickel chromium electrodeposition onto aluminium and its alloys
… can be completely covered with nickel due to the acidic nature and high temperature of the nickel electroplating process. One way of preventing this current density related problem is to use an electroless nickel undercoat before the nickel/chromium deposit is applied. The mechanism by which this …
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Interfacial transition zone composition and bonding in cementitious materials with asphalt-coated particles
… that certain chemical treatments, such as nitric acid, chromic acid, and maleic anhydride, oxidized the asphalt surface, as measured by increased carbonyl and sulfoxide spectroscopic indexes. Using the sessile drop method to measure surface free energy, these chemical treatments increased the …
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Association Between Smoking, Chemical Exposure and Hearing Loss in an Occupational Setting
Objective: Twenty-two million Americans or roughly 8% of the population are hearing impaired. This affects more than just the ability for one to hear. In the last three decades, younger Americans have shown a sharp increase in hearing impairment. Hearing loss affects social and emotional well being …