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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

Modificação quimica do amido de mandioca e estudo de sua aplicação em revestimento couche

Taparelli, Jesus Roberto 02 January 2005 (has links)
Orientador: Lucia Helena Innocentini Mei / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-04T05:33:53Z (GMT). No. of bitstreams: 1 Taparelli_JesusRoberto_M.pdf: 3122835 bytes, checksum: 2a962c8596eae20801290e744716b2cf (MD5) Previous issue date: 2005 / Resumo: Neste presente trabalho, foi estudada a grafitização de N-metilol acrilamida em amido de mandioca nativo, em meio aquoso, com proporções de 20, 30 e 40% em relação ao peso de amido, tendo como objetivo avaliar a aplicação técnica do produto resultante em formulações de tintas de revestimentos couché, aplicado sobre uma superficie de papel cartão. Estes novos polímeros, bem como o amido de mandioca e o amido de milho nativo, foram caracterizados por: (i) Análise Dinâmico-Mecânica (DMA), onde se conseguiu verificar moderadas modificações nas transições térmicas; (ii) Espectroscopia na região do Infravermelho(FT_IR); (iii) Microscopia Ótica (MO) e (iv) Microscopia Eletrônica de Varredura (MEV), onde percebeu-se mudanças morfológicas nos grânulos de amido modificado, que se apresentaram maiores que os do amido nativo. Para uma análise do comportamento destes polímeros em formulações de tintas de revestimentos couché, foi utilizado como referência padrão o látex de estireno-butadieno carboxilado, atualmente utilizado na indústria de papel, como ligante (ou resina) principal. Nas tintas de revestimentos couché desta tese, foram analisadas as aplicações feitas em papel cartão revestido, onde se utilizou para teste de imprimibilidade as seguintes análises: Pick teste seco; Pick teste úmido; alvura; teste de absorção superficial - K & N; brilho de impressão; rugosidade e absorção de óleo. Um bom revestimento deverá apresentar uma boa adesão à superficie do papel, evitando seu arrancamento do mesmo. Dos testes de arrancamento, todas as amostras dos revestimentos feitos com amido de mandioca, modificados com Nmetilol acrilamida, apresentaram excelentes resultados / Abstract: In this work, it was studied the graftization of native tapioca starch with of Nmethylol acrylamide (NMA) in aqueous media, at several proportions (20, 30 e 40%) relative to the starch weight, with the aim to evaluate the technical application of the product obtained in inks formulations used for finishing covering, applied over paper-card surfaces. The NMA and the native starch, as well as the starch derivatives, were characterized by: (i) Dynamic Mechanical Analysis (DMA), which showed mild modifications in the thermal transitions; (ii) lnfrared Spectroscopy (F_TIR); (iii) Oplical Microscopy (OM) and (iv) Electron Scanning Microscopy (SEM) which revealed morphological changes in the starch grains, being the modified starch grains bigger than those native. To analyze the behavior of these polymers in formulations of inks, used for finishing covering (known as couché paper card), it was utilized latex of styrene-butadiene - carboxylate as reference, current1yused as binder in the paper industry. For the paper card with the finishing covering it was utilized tests of printability as: dry pick test; wet pick test; whiteness; K and N test; shine of impression; roughness and oil absorption. In the printing process, the graphic ink used presents tacking that is responsible for a perpendicular force to the surface of the paper, which is able to peel its covering. The peeling tests done with the formulations modified with modified tapioca starch with Nmethylol acrylamide (NMA) presented very promising results / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química
2

Interfacial Adhesion Failure : Impact on print-coating surface defects

Kamal Alm, Hajer January 2016 (has links)
The aim of this work was to develop a solid knowledge on formulation effects controlling offset ink-paper coating adhesion and to identify key factors of the coating and printing process affecting it. Focus lay on comprehending the impact of pigment dispersant on ink-paper coating adhesion and ultimately on the print quality of offset prints. The work covers laboratory studies, a pilot coating trial designed to produce coated material with a span in surface chemistry and structure, and an industrial offset printing trial. The lab scale studies quantified ink-paper coating adhesion failure during ink setting with a developed laboratory procedure based on the Ink-Surface Interaction Tester (ISIT) and image analysis. Additional polyacrylate dispersant resulted in slower ink setting and reduced ink-paper coating adhesion, with a dependence on its state of salt neutralisation and cation exchange, mainly in the presence of moisture/liquid water. The industrial printing trial on pilot coated papers was designed to study how these laboratory findings affected full scale offset print quality. These trials confirmed the dispersant-sensitive effect on ink-paper coating adhesion, especially at high water feeds. Evaluation of prints from the printing trial resulted in two fundamentally different types of ink adhesion failure being identified. The first type being traditional ink refusal, and the second type being a novel mechanism referred to as ink-lift-off adhesion failure. Ink-lift-off adhesion failure occurs when ink is initially deposited on the paper but then lifted off in a subsequent print unit. In this work, ink adhesion failure by this ink-lift-off mechanism was observed to occur more often than failure due to ink refusal. Print quality evaluation of the industrial prints suggested that water induced mottle was caused by a combination of ink-surface adhesion failure, creating white spots on the print, together with variation in ink layer thickness due to emulsified ink. / <p>QC 20161019</p>
3

PUSHING THE BOUNDARIES OF CONCENTRATED DISPERSIONS, High Solids Content Bimodal Latex for Paper Coating Applications

Pacheco de Moraes, Raul 07 August 2012 (has links)
New processes for the production of polymeric dispersions with high solids content and low viscosity were developed, investigated and characterized. The specifications required for the desired application of paper coating, which constitutes one of the major innovative aspects of this thesis, requires in average particle sizes smaller than 200 nm. This particle size is significantly smaller than obtained in previous work in this area. The main objective of this project was to increase the solids content of existing products from ~50 to ~60 wt% while keeping the viscosity at low levels (< 1200 mPa•s at 20 s-1). In order to produce high solids content latexes with low viscosity, bimodal particle size distributions were resorted to. To obtain highest packing fraction, the small particle size population should be about 7 times smaller than the large particles, bringing the size of the small particles to less than 30 nm. Modified (micro)emulsion processes were developed in order to produce small particle size latex with reduced surfactant concentration and increased solids content. The large particle population was developed using a semi-batch emulsion polymerization process, simulating a product that is commercially available (~52 wt% solids content and viscosity of ~500 mPa•s at 20 s-1). To increase the solids content of this product up to 60 wt%, a second population of small particles was created using two approaches. In the first approach, the small particles were generated in situ using the modified (micro)emulsion approaches developed previously. This process resulted in latexes of ~ 60% solids content and viscosities lower than 500 mPa•s at 20 s-1. In the second approach, the second population of particles was created by the addition of seeds by using small cross-linked particles as pseudo inert-fillers. This process resulted in products with ~58% solids and viscosities lower than 1400 mPa•s at 20 s-1. The slightly decreased solids content and increased viscosity relative to the previous approaches is due to the difficulty in producing cross-linked seeds with particle sizes smaller than 30 nm at an acceptable concentration, causing deviations from ideal conditions. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2011-05-03 13:58:44.22
4

Oxydation par voie humide catalytique d’effluents industriels : catalyseurs métaux nobles supportés / Catalytic wet air oxidation of industrial wastes : noble metal supported catalysts

Grosjean, Nicolas 18 February 2010 (has links)
L’industrie produit de grandes quantités d’effluents aqueux qu’il convient de traiter. Des traitements alternatifs aux procédés biologiques doivent être développés pour certains effluents toxiques et/ou non biodégradables. L’oxydation en voie humide catalytique repose sur l’action de l’oxygène sur les polluants en phase aqueuse à haute température et haute pression. Préalablement à cette étude, des catalyseurs au Ru ou Pt supportés sur ZrO2 ou TiO2très actifs et très stables pour l’OVHC de polluants modèles et de quelques effluents réels ont été développés. Ce travail a examiné ces catalyseurs sur d’autres effluents réels : un effluent provenant d’une unité de production de membranes contenant du glycérol et du DMF, uneffluent de sauce de couchage provenant de l’industrie papetière et un concentrât de lixiviatde décharge. Les catalyseurs se sont révélés très actifs et stables pour la minéralisation du glycérol, mais une forte lixiviation a été observée lors de l’OVHC du DMF du fait de la présence d’amines. L’oxydation de l’effluent de sauce de couchage permet de minéraliser la charge organique, facilitant le recyclage de la charge minérale, avec une amélioration accrue de la biodégradabilité du surnageant en présence des catalyseurs. Enfin, l’ajout de catalyseurs lors de l’OVH du concentrât de lixiviat de décharge permet d’améliorer sa minéralisation et d’éliminer totalement les ions ammonium / Industries produce huge volumes of effluents which need to be treated before disposal.Alternative treatments to the more classical biological techniques are required in the case oftoxic and/or non biodegradable effluents. The wet air oxidation (WAO) and catalytic wet airoxidation (CWAO) are based on the reaction of an oxidant (oxygen) with the pollutants in aqueous phase at high temperature and pressure. Ru or Pt catalysts supported on zirconium and titanium oxides were previously shown to be highly active and stable in the CWAO of awide range of model compounds and real complex effluents. These catalysts were evaluated in the CWAO of problematic effluents: one containing glycerol and DMF, one paper coatingslip effluent and one concentrated landfill leachate. The catalysts showed high activity and stability in the CWAO of glycerol, while the metal leached upon DMF CWAO due to the presence of amines. WAO leads to the partial mineralization of the organic load in paper coating slip, allowing an easy separation recycling of mineral pigments, with an improved biodegradability of the supernatant with the use of a catalyst. The use of a catalyst upon landfill leachate WAO leads higher COT conversion and complete ammonia elimination

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