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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.
1

Synthesis Of Oil Based Hyperbranched Resins And Their Modification With Melamine Formaldehyde Resins

Karakaya, Ceylan 01 August 2005 (has links) (PDF)
In this research hyperbranched resins containing fatty acid residues like alkyds were synthesized. Dipentaerythritol which has six hydroxyl groups was used as the core molecule, and it was transesterified with (i) castor oil, and (ii) a mixture of castor oil and linseed oil at 240&deg / C in the presence of sodium hydroxide as catalyst. The resulting molecule, in either case, was then esterified with dimethylol propionic acid at 140&deg / C in the presence of p-toluene sulfonic acid as catalyst. Melamine-formaldehyde resin was synthesized to be used with the synthesized hyperbranched resins, and it was successfully modified by all hyperbranched resins at a ratio of 3:1. FTIR spectroscopy was used to characterize the hyperbranched resins and the thermal properties were determined by DSC. DSC showed that the hyperbranched resins decomposed between 315-345&deg / C. The viscosity of the resin that was synthesized by using only castor oil was 3.0 Pa.s and by using 50% linseed oil it was 1.0 Pa.s. When reacted with dimethylol propionic acid, the former&rsquo / s viscosity increased to 7.0 Pa.s, and the second&rsquo / s viscosity increased to 3.7 Pa.s. The hyperbranched resins showed excellent adhesion, gloss, flexibility, and formability. The mixture of hyperbranched resin plus melamine-formaldehyde resin samples had higher hardness values but lower gloss, adhesion and bending resistance values than the hyperbranched resins, and they had good impact and abrasion resistances.
2

Comparison of Properties of Pine Scrim Lumber Made from Modified Scrim

Leng, Weiqi 12 May 2012 (has links)
In this study southern pine scrim was treated with low molecular weight melamine formaldehyde (MF), phenolic formaldehyde (PF), and furfuryl alcohol (FA) at different loadings and formed into 25-mm thick panels. Mechanical, dimensional and biological properties were evaluated. Results showed that samples treated with 5 percent MF had the highest MOE, MOR and work to maximum load values (15.3 GPa, 54.2 MPa and 25.4 KJ/m3, respectively), while those treated with 10 percent MF had the highest internal bond and edgewise toughness values of 390 kPa and 12 N•m, respectively. With respect to dimensional stability, samples treated with 20 percent FA had the lowest swelling value (ASE = 36.8 percent), and the lowest water absorption value (27.5 percent). Dynamic swelling test revealed much higher ASE value (> 45 percent) for furfurylated samples. As for termite resistance, both untreated and treated samples had little weight loss (1.10-1.56 percent), high visual rating (8-9.3/10), and 100 percent mortality in laboratory test.
3

Porous Polymeric Monoliths by Less Common Pathways : Preparation and Characterization

Elhaj, Ahmed January 2014 (has links)
This thesis focuses on my endeavors to prepare new porous polymeric monoliths that are viable to use as supports in flow-through processes. Polymer monoliths of various porous properties and different chemical properties have been prepared utilizing the thermally induced phase separation (TIPS) phenomenon and step-growth polymerization reactions. The aim has been to find appropriate synthesis routes to produce separation supports with fully controlled chemical, physical and surface properties. This thesis includes preparation of porous monolithic materials from several non-cross-linked commodity polymers and engineering plastics by dissolution/precipitation process (i.e. TIPS). Elevated temperatures, above the upper critical solution temperature (UCST), were used to dissolve the polymers in appropriate solvents that only dissolve the polymers above this critical temperature. After dissolution, the homogeneous and clear polymer-solvent solution is thermally quenched by cooling. A porous material, of three dimensional structure, is then obtained as the temperature crosses the UCST. More than 20 organic solvents were tested to find the most compatible one that can dissolve the polymer above the UCST and precipitate it back when the temperature is lowered. The effect of using a mixture of two solvents or additives (co-porogenic polymer or surfactant) in the polymer dissolution/precipitation process have been studied more in depth for poly(vinylidine difluoride) (PVDF) polymers of two different molecular weight grades. Monolithic materials showing different pore characteristics could be obtained by varying the composition of the PVDF-solvent mixture during the dissolute­ion/precipitation process. Step-growth polymerization (often called polycondensat­ion reaction) combined with sol-gel process with the aid of porogenic polymer and block copolymer surfactant have also been used as a new route of synthesis for production of porous melamine-formaldehyde (MF) monoliths. In general, the meso- and macro-porous support materials, for which the synthesis/preparation is discussed in this thesis, are useful to a wide variety of applications in separation science and heterogeneous reactions (catalysis).
4

Síntesis, caracterización y aplicaciones de microcápsulas de aceite esencial de naranja (Citrus sinensis) en tejidos 100 % algodón / Síntese, caracterização e aplicações de microcápsulas de óleo essencial de laranja (Citrus sinensis) em tecidos 100 % algodão

Soares Rossi, Wagner 11 April 2022 (has links)
[ES] La tecnología de microencapsulación se ha utilizado en áreas como farmacología, medicina, ingeniería y diseño. Centrado en el área de la ingeniería, más específicamente, la selección de materiales y el desarrollo de productos, el carácter simbólico, perceptivo y funcional se puede combinar para el diseño de productos innovadores. Mediante la tecnología de microencapsulación se combinan una amplia gama de materiales de núcleo y membrana, más específicamente en la área textil, la aplicación de microcápsulas puede proporcionar el desarrollo de tejidos y materiales funcionales con propiedades específicas. En este contexto, este trabajo se propone verificar las condiciones y analizar la síntesis de microcápsulas de aceite esencial de naranja (Citrus sinensis) y estudiar su comportamiento cuando se aplica a tejidos de algodón. Para la síntesis de microcápsulas de membrana polimérica de melamina-formaldehído con núcleo de aceite esencial de naranja (Citrus sinensis) se utilizó el método de polimerización in situ. El aceite esencial de naranja se caracterizó por cromatografía de gases, espectroscopia infrarroja por transformada de Fourier, termogravimetría, las microcápsulas sintetizadas se caracterizaron por espectroscopia infrarroja por transformada de Fourier, termogravimetría, microscopía electrónica de barrido y haz de iones enfocado. Las microcápsulas poliméricas con núcleo de aceite esencial de naranja sintetizadas se aplicaron al tejido algodón mediante tres métodos diferentes (impregnación, pulverización y estampación). Después de la aplicación sobre el tejido de algodón, se realizón prueba de frote, pruebas de lavado y prueba de actividad antibacteriana en laboratorio para estudiar el comportamiento de las microcápsulas sobre el sustrato. La caracterización de las muestras de tejido con las microcápsulas aplicadas, antes y después de las pruebas de durabilidad, se realizó mediante microscopía electrónica de barrido y espectroscopía infrarroja por transformada de Fourier. Al finalizar se sistematizaron los procedimientos, condiciones y parámetros para la polimerización in situ así como la aplicación de microcápsulas poliméricas con núcleo de aceite esencial de naranja (Citrus sinensis) en tejido 100 % algodón, avanzando en el estudio de la selección de materiales para aplicación en textiles que se puede utilizar para el desarrollo de productos innovadores. Los resultados mostraron que se produjo la microencapsulación del aceite esencial de naranja volátil y que las microcápsulas aplicadas al tejido de algodón presentan actividad antibacteriana y resistien quince ciclos de lavado utilizando la norma ISO 105 C06: 2010. / [CA] La tecnologia de la microencaspulació s'utilitza en àrees com farmacologia, medicina, enginyeria i disseny. Centrat en l'àrea de l'enginyeria específicament, la selecció dels materials i el desenvolupament de productes de caràcter simbólic, perceptiu i funcional es pot combinar per al disseny de productes innovadors. Mitjançant la tecnologia de la microencapsulació es combinen una àmplia gamma de materials de nucli i membrana, més específicament en l'àrea tèxtil, l'aplicació de microcàpsules pot proporcionar el desenvolupament de teixits i materials funcionals amb propietats específiques. En aquest context, aquest treball es proposa verificar les condicions i analitzar la síntesi de microcàpsules d'oli essencial de taronja (Citrus sinensis) i estudiar el seu comportament quan s'aplica als teixits de cotó. Per a la síntesi de microcápsules de membrana polimèrica de melanina-formalheid amb nucli d'oli essencial de taronja (Citrus sinensis) s'ha utilitzat el mètode de polimeritzacio in situ. L'oli essencial de taronja es va caracteritzar per cromatografia de gasos, espectroscòpia infraroja per transformada de Fourier, termogravimetria, les microcàpsules sintetitzades es caracteritzaven per espectroscopia infraroja per transformada de Fourier, termogravimetria, microscòpia electrònica d'escombrat i feix d'ions enfocat. Les microcàpsules polimèriques amb nucli d'oli essencial de taronja sintetitzades s'han aplicat al teixit de cotó mitjançant tres mètodes diferents (impregnació, pulverització i estampat). Després de l'aplicació sobre el teixit de cotó, s'ha realitzat prova de trot, prova de llavat i prova de activitat antibacteriana en laboratori per a estudiar el comportament de les microcàpsules sobre el sustrat. La caracterització de les mostres de teixit amb microcàpsules aplicades, abans i després de les proves de durabilitat, s'ha realitzat mitjançat microscòpia electrònica d'escombrat i espectroescòpia infraroja per transformada de Fourier. Al finalitzar la sistematització dels procediments, condicions i paràmetres per a la polimerització in situ així com l'aplicació de microcàpsules polimèriques amb nucli d'oli essencial de taronja (Citrus Sinensis) en teixit de cotó 100%, avançat en l'estudi de la selecció de materials per a l'aplicació en tèxtil que es puga utilitzar en el desenvolupament de productes innovadors. Els resultats han demostrat que s'ha produït la microencapsulació del oli essencial de taronja volàtil i que les microcàpsules aplicades al teixit de cotó presenten activitat antibacteriana han resistit quinze cicles de llavat utilitzant la normativa ISO 105 C06:2010. / [EN] Microencapsulation technology has been used in areas such as pharmacology, medicine, engineering and design. Focused on the engineering area, more specifically, material selection and product development, the symbolic, perceptive and functional character can be combined for the design of innovative products. Through microencapsulation technology, a wide range of core and membrane materials are combined, more specifically in the textile area, the application of microcapsules can provide the development of fabrics and functional materials with specific properties. In this context, this work proposes to verify the conditions and analyze the synthesis of microcapsules of orange essential oil (Citrus sinensis) and study their behavior when applied to cotton fabric. For the microcapsules synthesis of melamine-formaldehyde polymeric membrane with orange essential oil core (Citrus sinensis), the in situ polymerization method was used. The orange essential oil was characterized by gas chromatography, Fourier transform infrared spectroscopy, thermogravimetric, the synthesized microcapsules were characterized by Fourier transform infrared spectroscopy, thermogravimetric, scanning electron microscopy and focused ion beam. The polymeric microcapsules with an orange essential oil core synthesized were applied to cotton fabric by three different methods (impregnation, spraying and screen printing). After application on the cotton fabric, friction tests, washing tests and antibacterial activity tests were performed in the laboratory to study the behavior of microcapsules on the substrate. The characterization of fabric samples with the applied microcapsules, before and after the durability tests, was performed by scanning electron microscopy and infrared spectroscopy by Fourier transform. At the end, the procedures, conditions and parameters for in situ polymerization as well as the application of polymeric microcapsules with an orange essential oil core (Citrus sinensis) in 100 % cotton fabric were systematized, advancing the study of the selection of materials for application in textiles that can be used for the development of innovative products. The results showed that microencapsulation of the volatile orange essential oil occurred and that the microcapsules applied to the cotton fabric showed antibacterial activity and resisted fifteen washing cycles using the ISO 105 C06: 2010. / Soares Rossi, W. (2022). Síntesis, caracterización y aplicaciones de microcápsulas de aceite esencial de naranja (Citrus sinensis) en tejidos 100 % algodón [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/182096 / TESIS

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