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101	Bacterial cellulose nanowhiskers to enhance the properties of plastics and bioplastics of interest in food packaging Martínez Sanz, Marta 01 July 2013 (has links) El presente trabajo tiene por objetivo estudiar las aplicaciones de los nanocristales o ¿nanowhiskers¿ extraídos mediante hidrólisis ácida de celulosa bacteriana (BCNW) para el desarrollo de materiales poliméricos y biopoliméricos con propiedades mejoradas para su uso en aplicaciones de envasado de alimentos. En primer lugar se estudió y optimizó el proceso de extracción de BCNW. Se desarrolló un procedimiento de extracción con ácido sulfúrico, que permitió obtener nanocristales con elevada relación de aspecto y cristalinidad y al mismo tiempo, un elevado rendimiento de extracción. Este procedimiento comprende una posterior etapa de neutralización que resultó ser necesaria para garantizar la estabilidad térmica de los nanocristales. El siguiente paso consistió en la formulación de materiales nanocompuestos con propiedades mejoradas incorporando BCNW en diferentes matrices plásticas, en concreto copolímeros de etileno-alcohol vinílico (EVOH), ácido poliláctico (PLA) y polihidroxialcanoatos (PHAs). Mediante las técnicas de electroestirado y estirado por soplado se generaron fibras híbridas de EVOH y PLA con BCNW. La incorporación de BCNW en las disoluciones empleadas para producir fibras modificó significativamente sus propiedades (viscosidad, tensión superficial y conductividad) y por tanto, la morfología de las fibras se vio afectada. Además, se generaron fibras con propiedades antimicrobianas mediante la incorporación de aditivos, maximizando el efecto antimicrobiano con la adición de sustancias de carácter hidrofílico. Seguidamente, se produjeron nanocompuestos por mezclado en fundido y se desarrollaron técnicas de pre-incorporación de BCNW para evitar la aglomeración de los mismos no sólo en matrices hidrofílicas como el EVOH, sino también en matrices hidrofóbicas como el PLA. La dispersión óptima de BCNW resultó en una mejora de las propiedades mecánicas y de barrera de los nanocompuestos. También se estudió la modificación de la superficie de los nanocristales mediante copolimerización con poli(glicidil metacrilato) para mejorar la compatibilidad de BCNW con una matriz hidrofóbica como el PLA. Se incluyen además los primeros resultados obtenidos en cuanto a la producción de nanobiocompuestos sintetizados por microorganismos, que consisten en PHAs con diferentes contenidos de hidroxivalerato reforzados con BCNW. Por último, se desarrollaron películas con propiedades de alta barrera basadas en películas de BCNW recubiertas con capas hidrofóbicas. El recubrimiento mediante la deposición de fibras por electrospinning seguido de homogeneización por calentamiento garantizó una buena adhesión entre las diferentes capas, protegiendo así las películas de BCNW del efecto negativo de la humedad. / Martínez Sanz, M. (2013). Bacterial cellulose nanowhiskers to enhance the properties of plastics and bioplastics of interest in food packaging [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/30312 / TESIS / Premios Extraordinarios de tesis doctorales Bacterial cellulose Cellulose nanocrystals Cellulose nanowhiskers Cellulose Acid hydolysis Nanocomposites Nanotechnology Packaging Electrospinning Blow spinning Fibres Melt compounding Casting Biopolymers Biobased materials Polymeric materials Ethylene vinyl alcohol EVOH Poly(lactic acid) PLA Polyhydroxyalkanoates PHAs PHBV Coatings Hydrophobization Poly(glycidyl methacrylate) Surface modification Barrier properties Mechanical properties Antimicrobial properties Thermal properties
102	[pt] AVALIAÇÃO METROLÓGICA DA MEDIÇÃO DO MÓDULO DE ELASTICIDADE DE MATERIAIS POLIMÉRICOS PELA MICROSCOPIA DE FORÇA ATÔMICA, NO MODO PEAK FORCE TAPPING / [en] METROLOGICAL EVALUATION OF THE MEASUREMENT OF THE MODULUS OF ELASTICITY OF POLYMERIC MATERIALS BY ATOMIC FORCE MICROSCOPY, IN THE PEAK FORCE TAPPING MODE JUAN DAVID CAICEDO VASQUEZ 01 September 2020 (has links) [pt] Ao longo das últimas décadas, mais intensamente, a microscopia de força atômica (AFM) tem sido utilizada em atividades de pesquisa e desenvolvimento, notadamente para a caracterização de materiais. Não obstante os avanços e sofisticações da técnica, a determinação do módulo de elasticidade de materiais poliméricos continua sendo um desafio dada a complexidade de caracterização de materiais complexos, comumente gerando expressivo espalhamento nos resultados de medição. Esta pesquisa de mestrado apresenta mapeamentos da morfologia e medições do módulo de elasticidade de celulose comercial (fibras de bambu e de eucalipto) e lignocelulósico, referenciados a materiais poliméricos sintéticos já caracterizados (considerados como padrão). A microscopia de força atômica (AFM), no modo peak force tapping, alternativamente fundamentada no modelo Derajaguin-Muller-Toporo, DMT (que é o modelo incorporado no software da Bruker, fabricante do equipamento AFM) e no modelo JohnsonKendall-Robert, JKR (proposto neste trabalho, fazendo-se uso de um algoritmo Matlab), foi utilizada como técnica de medição do módulo de elasticidade dos materiais investigados. A partir dos ensaios realizados, foi possível avaliar o método de medição com base em critérios metrológicos e determinar o modelo de cálculo mais apropriado para a caracterização dos materiais investigados. Para os materiais padrão utilizados como referência, e cujos valores do módulo de elasticidade são informados pelos respectivos fornecedores (E igual 2,7 mais ou menos 0,1 GPa, para o poliestireno e E igual 1,8 GPa, para a poliamida), o modelo JKR mostrou-se mais adequado para fundamentar o cálculo do módulo de elasticidade. Enquanto o modelo JKR reproduziu o valor do fabricante com 6,3 porcento, para o caso do poliestireno (E igual 2,540754 mais ou menos 0,056 GPa) e com 12,5 porcento, para o caso da poliamida (E igual 1,680050 mais ou menos 0,041 GPa), o modelo DMT produziu resultados com desvios superiores a 50 porcento do valor de referência considerado como padrão. Fundamentado nesses mesmos modelos DMT e JKR, o trabalho avaliou o módulo de elasticidade de outros materiais, mais especificamente: (i) filme de celulose extraída do eucalipto; (ii) filme de celulose microfobrilada comercial; (iii) filme de celulose microfibrilada, depositada no laboratório pela técnica de ultrassom e (iv) amostras de bambu (Dendrocalamus Giganteus), extraídas da seção externa e interna do colmo d o bambu. Os resultados são discutidos em conformidade ao rigor metrológico dos componentes estocásticos e determinísticos da incerteza associada às medições realizadas, confirmando que a microscopia de força atômica (AFM), no modo peak force tapping se apresenta como técnica promissora para ser utilizada como ferramenta metrológica para a caracterização de materiais poliméricos na escala nanométrica. / [en] Over the past few decades, more intensely, atomic force microscopy (AFM) has been used in research and development activities, notably for the characterization of materials. Despite the advances and sophistications of the technique, the determination of the modulus of elasticity of polymeric materials remains a challenge given the complexity of characterizing complex materials, commonly generating significant spread in the measurement results. This research presents mappings of the morphology and measurements of the elasticity modulus of commercial cellulose (bamboo and eucalyptus fibers) and lignocellulosic, referenced to already characterized synthetic polymeric materials (considered as standard). Atomic force microscopy (AFM), in the peak force tapping mode, alternatively based on the Derajaguin-Muller-Toporo model, DMT (which is the model incorporated by Bruker in its AFM software) and the Johnson-KendallRobert model, JKR (proposed in this work, using a Matlab algorithm), was used as a technique for measuring the elasticity module of the investigated materials. From the tests performed, it was possible to evaluate the measurement method based on metrological criteria and determine the most appropriate calculation model for the characterization of the investigated materials. For the standard materials used as a reference, whose elasticity modulus values are reported by the respective suppliers (E equal 2.7 more or less 0.1 GPa, for polystyrene and E equal 1.8 GPa, for polyamide), the JKR model proved to be most suitable to support the calculation of the modulus of elasticity. While the JKR model reproduced the manufacturer s value with 6.3 percent, for the case of polystyrene (E equal 2.540754 more or less 0.056 GPa) and with 12.5 percent, for the case of polyamide (E equal 1.680050 more or less 0.041 GPa), the DMT model produced results with deviations greater than 50 percent from the reference value taken as standard reference values. Based on these DMT and JKR models, the work evaluated the elasticity module of other materials, more specifically: (i) cellulose film extracted from eucalyptus; (ii) commercial microfiltered cellulose film; (iii) microfibrillated cellulose film, deposited in the laboratory by and ultrasound technique and (iv) samples of bamboo (Dendrocalamus Giganteus), extracted from the external and internal section of the bamboo stem. The results are discussed in accordance with the metrological rigor of the stochastic and deterministic components of the uncertainty associated with the measurements performed, confirming that the atomic force microscopy (AFM), in the peak force tapping mode, presents itself as a promising technique to be used as a metrological tool for the characterization of polymeric materials at the nanoscale. [pt] METROLOGIA [pt] MODELO JKR [pt] MODELO DMT [pt] MICROSCOPIA POR FORCA ATOMICA [pt] MATERIAIS POLIMERICOS [pt] CELULOSE [pt] BAMBU [en] METROLOGY [en] JKR MODEL [en] DMT MODEL [en] ATOMIC FORCE MICROSCOPY [en] POLYMERIC MATERIALS [en] PULP [en] BAMBOO
103	Технология производства кузова вездехода, предназначенного для эксплуатации в условиях Крайнего Севера : магистерская диссертация / The technology of production of the body of an all-terrain vehicle designed for operation in the Far North Ворухайлов, И. С., Vorukhailov, I. S. January 2018 (has links) В данной магистерской диссертации произведен обзор и анализ наземных транспортных средств, в частности колесных вездеходов на шинах сверхнизкого давления, получивших наиболее широкое распространение на территориях Крайнего Севера. Выявлены характерные особенности и условия эксплуатации автомобильного транспорта в арктической части РФ. На основании полученной информации разработана концепция вездехода на шинах сверхнизкого давления, наиболее адаптированного для использования в северных широтах. Исходя из предложенной конструкции, составлен технологический процесс изготовления и последующей сборки кузова данной колесной машины. Определены необходимые конструкционные материалы, используемые при производстве кузова вездехода. / In this master's dissertation, a survey and analysis of land vehicles, in particular wheeled all-terrain vehicles on ultra-low pressure tires, which have been most widely used in the Far North. The characteristic features and conditions of operation of motor transport in the Arctic part of the Russian Federation are revealed. Based on the information received, was developed the concept of an all-terrain vehicle on ultra-low pressure tires, most adapted for use in the northern latitudes. Proceeding from the proposed design, was compiled the technological process of manufacturing and subsequent assembly of the body of this wheeled vehicle. The necessary structural materials used in the manufacture of the body of an all-terrain vehicle are determined. ВЕЗДЕХОД КОЛЕСНАЯ МАШИНА ШИНЫ НИЗКОГО ДАВЛЕНИЯ КРАЙНИЙ СЕВЕР СНЕГОБОЛОТОХОД БОЛОТОХОД КУЗОВ РАМА КОМПОНОВКА ПОЛИМЕРНЫЕ МАТЕРИАЛЫ MASTER'S THESIS CROSS-COUNTRY VEHICLE WHEELED VEHICLE LOW-PRESSURE TIRES FAR NORTH ALL TERRAIN VEHICLE SWAMP BODY FRAME CONFIGURATION THE DESIGN OF THE CAR COMPOSITE MATERIALS POLYMERIC MATERIALS
104	Synthesis and characterization of a greener poly(vinyl acetate) adhesive / Syntes och karakterisering av ett ”grönare” PVAc-lim Zhang, Xiuting January 2023 (has links) To produce a greener adhesive is always an issue of concern to the commercial market and global environment. The environmental request for producing greener and bio-based adhesives leads to an increased awareness of replacing fossil-based components in adhesives with bio-based alternatives. Consequently, many researchers try to graft polymers from natural materials and some achievements have been made. In this work, an improved procedure to graft vinyl acetate (VAc) from chitosan (CS) is proposed and significant improvements were made regarding the increased Tg and water resistance. The achieved monomer conversion of VAc was ~97 %, and it was confirmed that chitosan-graft-poly(vinyl acetate) (CS-g-PVAc) could be used as a wood adhesive. The adhesive exhibited competitive properties to commercial PVAc wood adhesive. In the produced CS-g-PVAc, ~17 % of the fossil-based content of VAc could be replaced with bio-based chitosan, indicating an increased sustainability. At the same time there is no residual monomer during pressing, which avoid to pollute environment and hurt human. Compared to commercial PVAc, which has Tg at ~28 ℃, the Tg of CS-g-PVAc is ~42 ℃ At the same time, the water resistance of PVAc adhesive was successfully increased. poly(vinyl acetat)-ympad kitosan grönt lim Bearbetnings-, yt- och fogningsteknik Textile, Rubber and Polymeric Materials Textil-, gummi- och polymermaterial Polymer Technologies Polymerteknologi
105	Characterization of Fiber Orientation and Weld Line Effects in Reinforced Plastics with Reduced CO2eq Emissions Tolf, Anders, Johannesson, Markus January 2022 (has links) With increasing emphasis and regulations on the environmental footprint in industries, the integration of reduced carbon dioxide equivalent (CO2eq) plastic materials is desirable. Fiber-reinforced plastic materials mechanical properties differ with varying fiber orientations. Similarly, the welding line phenomenon, commonly present in more complex injection molded parts, decreases the mechanical performance. This thesis aims to experimentally investigate tensile behavior on reduced CO2eq reinforced plastics in different fiber orientations and weld line configurations. Ten materials with reduced CO2eq are investigated, the types of materials are as follows: PA6 (Polyamide6), PP (Polypropylene), and PA6/PP blend materials. Both short fiber-reinforced polymers (SFRP) and long fiber-reinforced polymers (LFRP) are investigated. The screening resulted in three selected materials for further investigation: one recycled PA6, one bio-based PA6/PP, and one alternative PP. The further investigation involves tensile testing in the five directions and three weld line configurations with non-standardized geometry specimens punched out from an injection molded plate with controlled fiber orientation. Two types of uniform fiber orientation plates are manufactured for the testing conditions, one with holes for weld line testing and one without for testing of orientation. The evaluated fiber orientations are 0° (fibers parallel to load direction), 22.5°, 45°, 67.5°, and 90° (fibers transverse to load direction). The weld line configuration consists of three consecutive holes with 96.5, 146.5, and 196.5 mm distances from the gating system. Three weld line test specimens are generated from each plate, they are denoted W1, W2, and W3 from their respective distance from the gating system, with W1 being closest to the gate. Optical microscopy of fiber orientation and failure modes for the test specimens are performed to investigate and validate the testing conditions. Varying fiber orientation was found to greatly affect the stress-strain behavior in all four materials investigated. The tensile strength was reduced from longitudinal to transverse fiber orientation, with the most significant reduction near flow direction. High variations were present for the brittle materials supposedly from their weakness to stress concentrations. Strain tended to increase from the lowest at 0° to the maximum at 45°, from which it again decreased to a mid-value at 90° for all materials. The weld line strength reduced significantly for the brittle materials, whereas the ductile materials experienced a much smaller reduction. The three weld line cases failed at similar stresses, while having different stiffness. Fiber-reinforced plastics GFRP Experimental Uniaxial tensile test Uniform fiber orientation plate Tensile strength Fiber orientation Weld line Fracture analysis Microscopy Textile, Rubber and Polymeric Materials Textil-, gummi- och polymermaterial Applied Mechanics Teknisk mekanik Composite Science and Engineering Kompositmaterial och -teknik Other Materials Engineering Annan materialteknik
106	Preventing fatal effects of overworking : Product design solution Adawi, Rahim January 2018 (has links) “Overworking to death” is a phenomenon that has been noticeable in developing countries. The cause of death is mainly through ischemic strokes. While the victims’ occupations differed, they all shared a common characteristic, being positioned in a sedentary work, ranging from IT workers to doctors. This project’s aim was to develop a product that prevented or decreased the strokes that derived from sedentary overwork. This was mainly tackled by preventing one of the three causes of developing blood props, slowed blood flow. In order to gather rich data of the phenomenon, a qualitative study was conducted in China, during two months. By doing an extensive structured sampling, information rich data could be gathered during a short period of time. Data were derived from observations, questionnaires and an interview, which then was interpreted to customer needs and the final product specification. The final product became a trouser with an in built dynamic compression mechanic, that can compress the veins mostly during sitting activities, in order to prevent blood stasis. The compression mechanic works like the Chinese finger trap; compressing the calves while sitting and stretching the legs forward. It is made only out of polysaccharides fibres; cotton and corn. / "Guolaosi" eller död från överarbete är ett fenomen som i regel uppkommer bland utvecklingsländer. Dödsorsaken är huvudsakligen genom stroke. Offrens yrken varierar allt från professorer, IT-arbetare till läkare. De delar dock en sak gemensamt; att arbeta under långa perioder stillasittande. Projektets mål var att utveckla en produkt som minskar dödliga följderna av sedentära överarbete, genom att förebygga en av de tre orsakerna för att utveckla blodproppar; saktad blodström. Målgruppen var då kineser av de yrken som hade tidigare drabbats av fenomenet. För att samla informationsrika data om fenomenet genomfördes en kvalitativ studie i Kina under två månader. Genom att göra en omfattande strukturerad provtagning kunde informationsrika data samlas under en kort tidsperiod. Fältstudien bestod av observationer, frågeformulär och en intervju, som då tolkades till kundbehov och eventuellt produktspecifikationen. Den slutliga produkten kom att bli ett par byxor med en inbyggd dynamisk komprimeringsmekanism, som kan komprimera venerna under sittande aktiviteter, för att förhindra saktad blodström. Kompressionsmekanismen fungerar som den kinesiska fingerfällan. Den komprimerar blodkärlen medan personen sitter och sträcker benen framåt. Produkten är konstruerad på så sätt att den kan tillverkas endast av polysackariders tråd, från bomull och majs. Vilket är lämpligt för Kinas lokala resurser. stroke DVT overworking karoshi guolaosi prolonged inactivity sedentary death product design China Sweden Sida MFS field study trouser pants sampling observation questionnaire interview blood circulation stasis cardiovascular disease cotton corn agenda 2030 Chinese finger trap textile fibre yarn soil erosion muscle pump mechanism gradual compression stockings GECS PECS pressure distribution blood clot veins therapy stool chair PE PTS economy class syndrome methodology plastic sample concept sketch stroke DVT överarbete karoshi guolaosi förlängd inaktivitet stillasittande död produkt design Kina Sverige Sida MFS fältstudie byxa byxor provtagning observation frågeformulär intervju blodcirkulation stasis kardiovaskulär sjukdom bomull majs agenda 2030 kinesisk fingerfälla textil fiber garn jord erosion muskel pump mekanism gradvis komprimering strumpor stödstrumpa tryck kraft GECS PECS tryckfördelning blod blodproppar vener terapi pall stol PE PTS ekonomi klass syndrom metodik plast prov koncept skiss Design Design Pharmacology and Toxicology Farmakologi och toxikologi Occupational Therapy Arbetsterapi Cardiac and Cardiovascular Systems Kardiologi Environmental Sciences Miljövetenskap Medical Ergonomics Medicinsk ergonomi Textile, Rubber and Polymeric Materials Textil-, gummi- och polymermaterial Composite Science and Engineering Kompositmaterial och -teknik Medical Materials Medicinska material och protesteknik

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