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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
311

Factors affecting penetration of acrylic resin in crust leather during retanning process

Song, Y., Zeng, Yunhang, Cao, M., Shi, B. 26 June 2019 (has links)
Content: Acrylic resin (AR) is a most popular retanning agent due to its selective filling property and advantage of formaldehyde-free. The retanning performance of acrylic resin mainly depends on its penetration depth and filling parts in leather. Therefore, to improve the retanning performance, it is necessary to fully understand the factors affecting the mass transfer and the distribution of acrylic resin in leather. We have found that the structure and the charge of leather and the dosage of acrylic resin rather than the molecular weight of acrylic resin are important factors affecting the penetration rate of acrylic resin in crust leather by using fluorescent tracer technique. In this study, from the view of electrostatic interaction, effects of neutralizing pH and retanning auxiliaries such as phenol sulfonic acid condensation (PSAC) and sodium carboxymethylcellulose (CMC) on the penetration and the distribution of acrylic resin in crust leather were investigated. Higher neutralizing pH led to a faster transfer of acrylic resin in leather because of the decrease in the positive charges of chrome-tanned leather (isoelectric point 7.1) and the increase in the negative charges of acrylic resin. Employing PSAC and CMC enhanced acrylic resin transfer in crust leather due to the dramatic increase in the negative charges of acrylic resin. These results indicated that decreasing the electrostatic binding force between acrylic resin and crust leather is beneficial to the penetration of acrylic resin in leather, which could be achieved by adjusting the neutralizing pH or using acrylic resin together with proper retanning auxiliaries. Take-Away: 1. Using phenol sulfonic acid condensation and sodium carboxymethylcellulose enhanced acrylic resin transfer in crust leather. 2. Decreasing electrostatic binding force between acrylic resin and crust leather is beneficial to penetration of acrylic resin in leather. 3. Increasing neutralizing pH or using proper retanning auxiliaries can decrease the electrostatic interaction between acrylic resin and crust leather effectively.
312

Příprava a charakterizace akrylových esterů PVAl / Synthesis and Characterization of PVAl Acrylic Esters

Hynštová, Karolína January 2008 (has links)
The diploma thesis deals with a detailed study of he esterification reaction between PVAl and acrylic and methacrylic acids. Tha goal is to prepared PVAl-based macromers bearing (meth)acrylic moieties bound to PVAl macromolecular backbone. Attention will be paid especially to equlibrium establishing times and to the influence of reaction mixture composition on the properties of resulting products.
313

Pro tebe / For You

Butula Cichá, Marie January 2012 (has links)
Ten figurativ paintings from kitchen. Technology - acrylic on canvas.
314

Le glycérol comme base structurale de coeurs de dendrimères obtenus par addition d'oxa-Michael sur des dérivés acryliques / Glycerol as structural base of dendrimer cores obtained by oxa-Michael addition to acrylic compounds

Nadeau, Frédéric 13 October 2017 (has links)
Le glycérol est une molécule bio-sourcée, abondamment disponible, issue de la saponification des corps gras et de la transestérification des huiles végétales. Les travaux portent sur l'utilisation du glycérol comme base structurale de cœurs de dendrimère, en particulier par addition d'oxa-Michael sur des dérivés acryliques. La fonctionnalisation en surface de dendrimères par des motifs imidazolium est explorée afin d’obtenir un dendrimère liquide ionique (DLI) aux propriétés thermosensibles. Le chapitre bibliographique est consacré dans une première partie, aux méthodes de synthèse de dendrimère mettant en jeu des dérivés acryliques et à leurs applications et dans une seconde partie, aux travaux consacrés à l'addition oxa-Michael d'alcools sur des dérivés acryliques. Le deuxième chapitre porte sur les synthèses, à partir du glycérol, de la base structurale du cœur de dendrimère. La réaction d’acylation du glycérol par le chlorure d’acryloyle est présentée ainsi que les différentes constructions de dendrimères poly(estersulfure) à partir du triacrylate de glycérol. L’addition nucléophile du glycérol sur l’acroléine, l’acrylamide, des acrylates et l’acrylonitrile a été étudiée. Avec les acrylates, la réaction d'addition nucléophile est en compétition avec la réaction de transestérification, à l’exception de l'acrylate de t-butyle résistant en milieu basique. Avec l’acrylonitrile, la synthèse du 1,2,3-tricyanoéthylglycéryléther a pu être menée sans solvant, en 5 heures à température ambiante, en présence d’un catalyseur peu coûteux (la soude 4 mol %) avec un rendement de 88% et une pureté de 99% sans méthode de purification. Les intermédiaires de réaction mono- et di-cyanoéthylglycéryléther ont été caractérisés et ont permis un suivi cinétique de la réaction. La synthèse de dendrimères poly(amidoamine) à partir du 1,2,3-tricyanoéthylglycéryl éther fait l’objet du troisième chapitre : synthèse des générations G0 à G2,5, caractérisation des dendrimères. Des défauts de structure dus à une cyclisation intramoléculaire ont été mis en évidence par HRMS pour les générations entières et les dendrimères de demi-génération Gn+5 (n entier) sont purifiés par colonne chromatographique. Différentes voies de synthèse pour l’obtention d’un DLI à termini imidazolium sont présentées / Glycerol is a bio-based molecule, abundantly available, from the saponification of triglyceride and the transesterification of vegetable oils. The work described in this PhD thesis concerns the use of glycerol as structural base of dendrimer's core, in particular by oxa-Michael addition on acrylic derivatives. The surface functionalization of dendrimers by imidazolium units is explored in order to obtain an ionic liquid dendrimer (DLI) with thermosensitive properties. In the first part, the bibliographic chapter presents the methods of dendrimers synthesis involving acrylic derivatives and their applications and, in a second part, the work introduces the oxa-Michael addition of alcohols to acrylic derivatives. The second chapter deals with the synthesis of the structural base of the dendrimer core from glycerol. The reaction of acylation of glycerol with acryloyl chloride is presented as well as the various constructions of poly(estersulfide) dendrimers from glycerol triacrylate. The nucleophilic addition of glycerol to acrolein, acrylamide, acrylates and acrylonitrile has been studied. With the acrylates, the nucleophilic addition reaction is in competition with the transesterification reaction, with the exception of t-butyl acrylate, resistant in basic medium. With acrylonitrile, the synthesis of 1,2,3-tricyanoethylglycerylether was carried out without solvent in 5 hours at room temperature in the presence of an inexpensive catalyst (4 mol% sodium hydroxide) in a yield of 88% and purity of 99% without purification method. The mono- and di-cyanoethylglycerylether reaction intermediates were characterized and allowed kinetic monitoring of the reaction. The synthesis of poly(amidoamine) dendrimers from 1,2,3-tricyanoethylglycerylether is the subject of the third chapter: synthesis of generations G0 to G2,5 and characterization of dendrimers. The defects in the structure due to intramolecular cyclization have been demonstrated by HRMS for generations Gn and the half-generation dendrimers Gn+5 (n=0, 1, 2) were purified by chromatographic column. Several routes of synthesis for the synthesis of DLI with imidazolium termini are presented
315

Användning av den vattenbaserade emulsionspolymeren för utveckling avspecifika egenskaper hos tegel och betong: syntes och karakterisering / Application of the Water-based Emulsion Polymer for Development of SpecificProperties of Brick and Concrete: Synthesis and characterization

Nasr, Shahab January 2022 (has links)
Improvement properties of building materials are essential. In this dissertation thesis, the main concern had been on synthesizing a new resin to improve the properties of concrete and brick. Solvent-based polymers have been used for many years to improve the quality of building materials. In contrast to solvent-based polymers, water-based emulsion polymers are one of the available solutions that have been used to improve the quality of building materials. Several advantages can be enumerated for water-based emulsion polymers such as lower volatile organic compounds (VOC), easier application, lower carbon dioxide emissions in the production, and fossil resource preservation. Water-based emulsion polymers are synthesized from simple homopolymers to copolymers with various monomers and additives. In this research, the synthesis and characterization of water-based acrylic styrene emulsion copolymer had been the main concern. Acrylic monomers could develop the qualities such as thermoplasticity, water solubility, and a longer lifespan of the polymer, while styrene monomers will impart water resistance and stiffness properties. In this research, the first step had been the synthesis of a water-based emulsion copolymer. Furthermore, considering the importance of biodegradability of the synthesized copolymer, the research followed by the replacement of ingredients such as emulsifiers with higher biodegradability characteristics with eco-friendly by-products, i.e. reducing the microplastic hazards. As a result, the copolymer could be decomposed better, and consequently, problems with the release of microplastics will be reduced. The synthesized water-based acrylic styrene emulsion copolymer was characterized by FTIR, DSC, and TGA. The FTIR results confirmed successful emulsion polymerization of acrylic styrene copolymer. DSC results confirmed the formation of an amorphous thermoplastic type of copolymer with a single glass transition temperature. The TGA result also confirms a single decomposition temperature. The film formation was carried out using a film applicator to evaluate the film formation properties. The substitution of the superseded emulsifiers (both anionic and nonionic) did not alter the characteristics of the synthesized copolymer, while some of the qualities such as water absorbance of the dried copolymer are improved (a water absorption test was carried out). To improve the quality of both synthesized emulsion copolymers (with conventional and superseded emulsifiers), the nanocomposite of the emulsion copolymer was prepared (Cloisite 30B at a concentration of 0.2 to 1 %). The synthesized nanocomposite showed better water resistance in the coating application in contrast with emulsion copolymer. The next stage of the research has been concentrated on the application of the synthesized water-based emulsion copolymer to building materials (concrete and brick). The synthesis copolymer has been applied as a coating on the surface of the concrete and bricks. Moreover, the synthesis copolymer was used as one of the ingredients in the mixture of the concrete. The promising results for the coating improved when the synthesis polymer was modified with nanoparticles (Cloisite 30B at a concentration of 1 % weight of the latex). Incorporating the synthesized copolymer in the mixture of concrete caused decreasing in the density of concrete by 4 % ( via air voids formation mechanism). However, water absorption was improved when synthesized copolymer was mixed with the concrete. The synthesized copolymer and the nanocomposite is a suitable coating for the concrete and brick. Furthermore, this copolymer is a suitable water-based coating with improved properties in building materials.
316

Studies on the microbial production of acrylic acid

Dalal, Rajen Kantilal January 1980 (has links)
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nutrition and Food Science, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 201-212. / Rajen Kantilal Dalal. / M.S.
317

Stability of linoleic acid and its reactivity with bone cement components / Stabilitet av linolsyra och dess reaktivitet med bencementkomponenter

Ayyachi, Thayanithi January 2021 (has links)
Akrylbaserat bencement är den gyllene standarden vid ryggförstärkningsförfaranden. Modifiering av akrylbencement med linolsyra har resulterat i attraktiva egenskaper vilka möjliggör lättare hantering för kirurger och minskar efterföljande komplikationer såsom närliggande ryggradsfrakturer. Även om de attraktiva egenskaperna hos linolsyramodifierat bencement är kända är ännu förståelsen för hur linolsyra påverkar egenskaperna outforskade. Som en komponent i bencement måste linolsyra steriliseras innan den används i bencement. Det finns emellertid oro för att autoklavsterilisering av linolsyra orsakar nedbrytning. Dessutom är det oklart vad som händer med linolsyra i härdat bencement över tid. I detta examensarbete utvärderades steriliserad och osteriliserad linolsyra. Linolsyra blandades med olika komponenter som finns i bencementet såsom aktivator, initiator, monomer och inhibitor, i närvaro och frånvaro av lösningsmedel. De efterföljande förändringarna studerades genom 1H NMR och UV-VIS. Resultaten visade att linolsyra bryts ned av sterilisering och oxidation. Oxidationen av linolsyra berodde på sterilisering, temperatur, lösningsmedel och mängden syrexponering. Det bekräftades genom 1H NMR och UV-VIS att linolsyra reagerade (steriliserad och osteriliserad) med aktivatorn, initiatorn och monomeren. Dessa reaktioner kan minska tillgängligheten av komponenterna för in situ-polymerisation av monomeren, och därmed förändra bencementens egenskaper, vilket i sin tur bidrar till lättare hantering under förstärkningsförfarandet och reducerar intilliggande ryggradsfrakturer efter operation. / Acrylic bone cement is the gold standard in vertebral augmentation procedures. Modification of acrylic bone cement using linoleic acid has resulted in attractive properties that enable convenient handling by surgeons and reduce follow-up complications such as adjacent vertebral fractures. Even though the attractive properties of linoleic acid-modified bone cement are acknowledged, the understanding of how it imparts those properties remain unexplored. As a component in bone cement, linoleic acid needs to be sterilized before its use in bone cement. However, there are apprehensions whether autoclave sterilization of linoleic acid causes degradation. In addition, it is unclear what happens with linoleic acid in hardened bone cement over time.  In this thesis, sterilized and unsterilized linoleic acid were evaluated alone and treated with different components of the bone cement such as activator, initiator, monomer, and inhibitor, in the presence and absence of solvent, and the ensuing changes were monitored through 1H NMR and UV-VIS. The results showed that linoleic acid degraded due to sterilization and oxidation. The oxidation of linoleic acid depended on sterilization, temperature, solvent, and the amount of oxygen exposure. As confirmed through 1H NMR and UV-VIS, linoleic acid (sterilized and unsterilized) reacted with the activator, initiator, and monomer. These reactions could reduce the availability of the components for the in-situ polymerization of the monomer, thus altering the properties of the bone cement including convenient handling during the operation and reduced adjacent vertebral fractures post the operation.
318

Synthesis of Hybrid Latexes and Polymerization Kinetics of Functional Latexes

Bas, Serkan 03 September 2009 (has links)
No description available.
319

Stabilized Metal Nanoparticle-Polymer Composites: Preparation, Characterization and Potential Applications

Anyaogu, Kelechi Chigboo 03 November 2008 (has links)
No description available.
320

Oxygen and Carbon Dioxide Permeability of EEA/PEO Blends and Microlayers

Pethe, Vishwas Vyankatrao January 2008 (has links)
No description available.

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