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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.
31

A study of the colloidal stability of mixed abrasive slurries of silica and ceria nanoparticles for chemical mechanical polishing

Lin, Fangjian Unknown Date
No description available.
32

A fundamental study of bubble-particle interactions through zeta-potential distribution analysis

Wu, Chendi Unknown Date
No description available.
33

Waterflood and Enhanced Oil Recovery Studies using Saline Water and Dilute Surfactants in Carbonate Reservoirs

Alotaibi, Mohammed 2011 December 1900 (has links)
Water injection has been practiced to displace the hydrocarbons towards adjacent wells and to support the reservoir pressure at or above the bubble point. Recently, waterflooding in sandstone reservoirs, as secondary and tertiary modes, proved to decrease the residual oil saturation. In calcareous rocks, water from various resources (deep formation, seawater, shallow beds, lakes and rivers) is generally injected in different oil fields. The ions interactions between water molecules, salts ions, oil components, and carbonate minerals are still ambiguous. Various substances are usually added before or during water injection to enhance oil recovery such as dilute surfactant. Various methods were used including surface charge (zeta potential), static and dynamic contact angle, core flooding, inductively coupled plasma spectrometry, CAT scan, and geochemical simulation. Limestone and dolomite particles were prepared at different wettability conditions to mimic the actual carbonate reservoirs. In addition to seawater and dilute seawater (50, 20, 10, and 1 vol%), formation brine, shallow aquifer water, deionized water and different crude oil samples were used throughout this study. The crude oil/water/carbonates interactions were also investigated using short and long (50 cm) limestone and dolomite rocks at different wettability and temperature conditions. The aqueous ion interactions were extensively monitored via measuring their concentrations using advanced analytical techniques. The activity of the free ions, complexes, and ion pairs in aqueous solutions were simulated at high temperatures and pressures using OLI electrolyte simulation software. Dilute seawater decreased the residual oil saturation in some of the coreflood tests. Hydration and dehydration processes through decreasing and increasing salinity showed no impact on calcite wettability. Effect of individual ions (Ca, Mg, and Na) and dilute seawater injection on oil recovery was insignificant in compare to the dilute surfactant solutions (0.1 wt%). The reaction mechanisms were confirmed to be adsorption of hydroxide ions, complexes and ion pairs at the interface which subsequently altered the surface potential from positive to negative. Results in this study indicate multistage waterflooding can enhance oil recovery in the field under certain conditions. Mixed streams simulation results suggest unexpected ions interactions (NaCO3-1, HSO4-1, NaSO4-1 and SO4-2) with various activities trends especially at high temperatures.
34

Estudo das propriedades eletricas das hemacias utilizando pinça optica / Study of electrical properties of red blood cell using optical tweezers

Fernandes, Heloise Pockel 14 August 2018 (has links)
Orientadores: Maria Lourdes Barjas-Castro, Carlos Lenz Cesar / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-14T15:31:46Z (GMT). No. of bitstreams: 1 Fernandes_HeloisePockel_M.pdf: 11930391 bytes, checksum: ee8655790477f44b4f7a68132905dc0c (MD5) Previous issue date: 2009 / Resumo: A membrana eritrocitária contém proteínas e glicoproteínas imersas em uma bicamada lipídica que possui um comportamento viscoelástico. Algumas glicoproteínas contém ácido siálico, que é o principal responsável pelas cargas negativas na superfície da hemácia que quando em solução cria um potencial elétrico (Ç) repulsivo. A carga elétrica negativa da superfície eritrocitária influencia na distribuição dos íons da solução ao redor da célula formando uma dupla camada de íons. A primeira, conhecida como camada compacta de cargas ou "Stern" é formada por íons rigidamente ligados à hemácia e a segunda camada é composta por íons distribuídos difusamente e conhecida como camada difusa. O objetivo deste estudo foi medir o potencial zeta (Ç), a espessura da dupla camada das cargas iónicas (DLC) ao redor da hemácia, e a força de agregação eritrocitária com diferentes meios potencializadores da aglutinação utilizando pinça óptica. (...continua) / Abstract: The red blood cell (RBC) membrane contains proteins and glycoproteins embedded in a fluid lipid bilayer that confers viscoelastic behavior. Sialylated glycoproteins of the RBC membrane are responsible for a negatively charged surface, which creates a repulsive electric zeta potential (Z) between the cells.The compact layer of charge or Stern consists of ions rigidly bonded to the cell and the double layer includes ions diffusely distributed around the cell. The aim of this study was to measure the RBC double layer thickness of the charge (DLC) around the cell, zeta potential (Z) and cell aggregation force in agglutination potentiator solutions, using optical tweezers. (¿to be continue) / Mestrado / Mestre em Farmacologia
35

Elaboração e caracterização de filmes coacervados à base de gelatina/quitosana, gelatina/pectina e gelatina/goma arábica / Preparation and characterization of coacervates films on based gelatin/chitosan, gelatin/pectin and gelatin/gum arabic

Braga, Andréa Helena Ferreira, 1980- 09 October 2013 (has links)
Orientador: Carlos Raimundo Ferreira Grosso / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-23T08:09:57Z (GMT). No. of bitstreams: 1 Braga_AndreaHelenaFerreira_D.pdf: 2190091 bytes, checksum: 46376779b7866dd62ac05c2a6abc7be6 (MD5) Previous issue date: 2013 / Resumo: A eficiente combinação entre proteínas e polissacarídeos produz filmes biodegradáveis com melhores propriedades funcionais, a interação associativa entre os grupamento presentes na cadeia polimérica dos biopolímeros gera uma rede polimérica mais coesa e resistente. Esta associação, em geral, ocorre através das interações eletrostáticas entre os biopolímeros que é controlada pelas condições de pH, força iônica e proporção estequiométrica dos polimeros, entre outros parâmetros. O objetivo deste trabalho foi utilizar o método de coacervação na elaboração de filmes a base de gelatina-quitosana (GEL/QUI), gelatina-pectina (GEL/PEC) e de gelatina-goma arábica (GEL/GAR) com o intuito de promover maiores interações intermoleculares entre os biopolímeros, formando filmes mais resistentes mecanicamente e menos susceptíveis a ação da água. O desenvolvimento deste trabalho pode ser dividido em: 1-) Análise da solução filmogênica de GEL/QUI ou PEC ou GAR (em várias proporções estequiométricas): nesta etapa foi feito um estudo para definir o pH de coacervação para cada formulação utilizando o ?-potencial zeta. No pH de coacervação ocorre a máxima interação eletrostática entre os biopolímeros gerando carga elétrica neutra para a solução filmogênica (?-potencial zeta igual a zero), devido a neutralização da carga elétrica positiva (-NH4+) com a carga elétrica negativa (-COO-) dos biopolímeros. 2-) Elaboração dos filmes coacervados foi realizada em várias proporções estequiométricas no seu devido pH de coacervação. 3-) Caracterização dos filmes de acordo com o aspecto visual, propriedades mecânicas, permeabilidade ao vapor de água (PVA), solubilidade em água (SOL), umidade (UMI) e opacidade (Op). Análises complementares de difração de raio-X (DRX), espectroscopia de infravermelho (FTIR), microscopia eletrônica de varredura (MEV) e calorimetria diferencial de varredura (DSC) foram realizadas em alguns filmes. 4-) Seleção dos filmes: foi escolhida a proporção estequiométrica que produziu filmes com maior resistência mecânica, menor PVA e SOL. 5-) Concentração do material polimérico: na formulação selecionada foram testadas maiores concentrações de material polimérico (4, 6, 8 e 10%) com o intuito de reduzir o tempo de secagem dos filmes coacervados. Estes filmes foram novamente caracterizados (propriedades mecânicas, PVA, SOL e UMI). A concentração de material polimérica escolhida para prosseguir o estudo associou o menor tempo de secagem sem alterar a PVA e SOL dos filmes. 6-) Adição do plastificante: nesta etapa foi avaliado o tipo de plastificante (triacetina e glicerol) e a sua concentração (2,5, 5, 7,5, 10, 15, 20, 25 e 30g de plastificante/100g de material polimérico). Os filmes coacervados de GEL/QUI foram elaborados em pH alcalino (pH de coacervação entre 6,2-7,2) por combinar um polissacarídeo catiônico (QUI) com a GEL. Formulações com maior teor de GEL (10:1 e 20:1 de GEL/QUI) confere ao filme coacervado maior resistência à ruptura, flexibilidade e menor PVA. As análises de difração de raio-X e de FTIR evidenciam a presença de interações eletrostáticas atrativas entre as cadeias da gelatina e a quitosana. Ao comparar os filmes coacervados com os filmes compostos (sem ajuste de pH) verificou-se que o método de coacervação conferiu ao filme maior tensão na ruptura, menor PVA e menor SOL. Ao aumentar a concentração de material polimérico de 2% para 6% constatou-se redução pela metade do tempo de secagem, além de promover maior resistência a ruptura e menor PVA. Os filmes coacervados de GEL/PEC e GEL/GAR foram elaborados em pH ácido (pHcoacervação igual a 4,0 e 4,5-5,0, respectivamente), isto ocorre devido a interação do grupo carboxil (-COO-) dos polissacarídeos aniônicos com o grupo amina (-NH4+) da GEL, já que a proteína encontra-se carregada positivamente somente em pHs abaixo do seu ponto isoelétrico - pI (pI da GEL 4,8-5,2). Para filme coacervado de GEL/PEC, somente a solução filmogênica contendo 20:1 de GEL/PEC apresentou-se homogênea e com em condição de coacervação (pHcoacervação=4,0). O espectro de FTIR do filme coacervado de GEL/PEC (20:1) mostrou que o grupo carboxil da PEC pode estar interagido com o grupo amina da GEL gerando novos grupamentos amida (1630 e 1530 cm-1). A incorporação do glicerol foi mais eficiente na matriz polimérica da GEL/PEC do que a triacetina, isto foi comprovado pela análise visual e pela difração de raio-X. Filmes coacervados de GEL/GAR apresentaram-se coesos, uniformes e homogêneos. Filmes coacervados com alto teor de GEL mostraram-se mais resistentes e flexíveis e menos solúveis em água do que as formulações com menor teor de GEL (1:1 e 2:1 de GEL/GAR), resultados confirmados pelas análises de FTIR, DSC e DRX. O método de coacervação formou filmes mais resistentes mecanicamente e a ação da água do que nos filmes não coacervados (sem ajuste de pH). O aumento da concentração do material polimérico de 2 para 6% reduziu o tempo de secagem do filme de GEL/GAR (10:1) pela metade sem alterar suas propriedades funcionais. Todos os filmes coacervados de GEL/QUI, PEC ou GAR, de modo geral, apresentaram o mesmo comportamento frente a a adição do plastificante. A adição do glicerol foi mais eficiente devido sua melhor incorporação na matriz polimérica produzindo filmes coacervados mais flexíveis, mais resistentes, com menor PVA e mais transparentes do que os filmes coacervados contendo triacetina. Os resultados apresentados neste trabalho confirmam a eficiencia do método de coacervação em melhorar a compatibilidade, e consequentemente, intensificando a interação eletrostáticas entre a proteína e o polissacarídeo. Isto reflete diretamente nas propriedades funcionais dos filmes coacervados, pois a maior interação entre os biopolímeros promove a formação de uma rede polimérica mais densa e coesa, gerando filmes com maior TR, menor PVA, menor ELO e em alguns formulações mais resistentes a ação da água (menor SOL) / Abstract: The efficient combination of proteins and polysaccharides produces biodegradable films with improved functional properties; the associative interaction between the groupings present in the polymer chain of biopolymers generates a more cohesive and resistant polymer network. This association generally occurs through electrostatic interactions between the biopolymers which is controlled by the conditions of pH, ionic strength and stoichiometric ratio of polymers, among other parameters. The aim of this study was to use the coacervation method in developing films based on gelatin-chitosan (GEL/QUI), on gelatin-pectin (GEL/PEC) and on gelatin-gum arabic (GEL/GAR), in order to promote greater intermolecular interactions between biopolymers, forming mechanically stronger films and less susceptible to the action of water. The development of this work can be divided into: 1-) Analysis of the film solution GEL/QUI or PEC or GAR (in various stoichiometric ratios): in this step a study was done to determine the pH of coacervation for each formulation using ?-zeta potential. At pH of coacervation occurs maximum electrostatic interaction between biopolymers generating a neutral electric charge for filmogenic solution (? - zeta potential of zero), due to neutralization of the positive charge (-NH4+) with negative charge (-COO-) of biopolymers. 2-) Development of coacervated films was held in various stoichiometric ratios in its proper pH of coacervation. 3-) Characterization of films according to the visual appearance, mechanical properties, permeability to water vapor (PVA) water solubility (SOL), humidity (UMI) and opacity (Op). Complementary analyzes of X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differencial scanning calorimetry (DSC) were performed in some films. 4-) Selection of films: it was chosen a Stoichiometric ratio which produced films with higher mechanical strength and lower PVA SOL. 5-) Concentration of polymeric material: higher concentration of polymeric material (4, 6, 8, and 10% ) were tested in the selected formulation in order to reduce the drying time of the coacervated films. These films were further characterized (mechanical properties, PVA, SOL and UMI). The concentration of polymeric materials chosen for further study associated the lowest drying time without changing the SOL and PVA films. 6-) Addition of plasticizer: In this step the type of plasticizer (triacetin or glycerol) and its concentration was evaluated (2.5, 5, 7.5, 10, 15, 20, 25 and 30g plasticizer/100g polymeric material). The coacervated films GEL/CHI were prepared at alkaline pH (pH of coacervation between 6.2-7.2) by combining a cationic polysaccharide (QUI) with GEL. Formulations with higher content of gel (10:1 and 20:1 GEL/QUI) gave the coacervated film higher tensile strength, flexibility and less PVA. The analysis of X- ray diffraction and FTIR showed the presence of attractive electrostatic interactions between the chains of gelatin and chitosan. Comparing coacervated films with composite films (without pH adjustment) it was found that the coacervation method gave the highest film tensile strength, lower PVA and lower SOL. By increasing the concentration of polymeric material from 2% to 6% a reduction by half of the drying time was found promoting a greater resistance to breakage and lower PVA. The coacervate films GEL/PEC and GEL/GAR were prepared in acidic pH (pH of coacervation equal to 4.0 and 4.5 to 5.0, respectively), this occurs due to interaction carboxyl group (-COO-) of anionic polysaccharides with amino group (-NH4+) of GEL, since the protein is positively charged at pHs only below its isoelectric point - pI (pI of 4.8 to 5.2 GEL). To coacervate film GEL/PEC, only film solution containing 20:1 GEL/PEC appeared homogeneous and in condition coacervation (pH of coacervation = 4.0). The FTIR spectrum of the coacervated film GEL/PEC (20:1) showed that the carboxyl group of the PEC may have been interacted with the amino group generating new clusters of GEL amide (1630 and 1530 cm-1). The incorporation of the glycerol was more efficient in the polymer matrix of GEL/PEC than triacetin. It was confirmed by visual analysis and by X -ray diffraction. Films coacervated GEL/GAR presented themselves cohesive, uniform and homogeneous. Coacervated films with high gel content were more resistant and flexible and less soluble in water than the formulations with lower content of gel (1:1 to 2:1 GEL/GAR), which was confirmed by analysis of FTIR, DSC and XRD. The coacervation method formed films more mechanical and water resistant than in the non coacervated films. (without pH adjustment). Increasing the concentration the polymeric material from 2 to 6 % reduced the drying time of the film GEL/GAR (10:1) by half without altering their functional properties. All coacervated films GEL/QUI, PEC or GAR, in general, showed the same behavior in addition of plasticizer. The addition of glycerol was more efficient because of its better incorporation into the polymer matrix coacervated producing more flexible films, tougher, with less PVA and more transparent than coacervated films containing triacetin. The results presented here confirm the efficiency of the coacervation method to improve the compatibility, thus intensifying the electrostatic interaction between protein and polysaccharide. This highly reflects in the functional property of coacervated films, since the bigger interaction among biopolymers promotes the formation of more dense and united polymeric net, generating films with higher TR, smaller PVA, less ELO in some formulations and more resistant to the action of water (less SOL) / Doutorado / Consumo e Qualidade de Alimentos / Doutora em Alimentos e Nutrição
36

Structuration par voie colloïdale de nanopoudres de boehmite à partir de systèmes mixtes organique/inorganique / Structuration by colloidal way of nanopowders boehmite from organic/inorganic hybrid systems

Belounis, Fahouzi 02 July 2015 (has links)
La recherche s’appuie pour une grande part sur le développement de nanomatériaux. Ceux-ci constituent, en effet, les matières premières des nanosciences et ouvrent à l’industrie des perspectives extrêmement larges. Le développement des céramiques nécessite une grande maîtrise des procédés d'élaboration qui permettent d'obtenir des microstructures appropriées à l’élaboration de matériaux denses pour différentes applications par exemple biomédicales. Les évolutions récentes concernent les matériaux hybrides et bio-inspirés ; les problèmes de mise en forme et de structuration multi-échelles de ces derniers incitent au développement de nouveaux procédés telle que l’approche nouvelle dite ascendante (bottom-up) consistant à fabriquer un matériau à échelle microscopique voir macroscopique à partir de ses particules nanométriques.Dans ce contexte, les travaux de cette thèse ont pour objectif de faciliter, par l’intermédiaire d’une modification de surface, la mise au point d’une technique de mise en forme originale pour l’élaboration de céramiques issues d’un matériau nanométrique de type oxyde: la granulation par coagulation. Nous nous sommes intéressés au cas d’une nanopoudre de boehmite (AlO(OH)). Cependant, cette poudre nanométrique de boehmite présente de multiples instabilités en suspension. En effet, cette poudre est soumise à de fortes gélifications en fonction du pH et à basse concentration. Il est nécessaire dans ce cas pour obtenir une suspension stable de modifier les propriétés de surface. En conséquence, une partie de ces travaux est consacrée à la fonctionnalisation de surface par des organosilanes. Cette modification de surface n’est cependant qu’une étape à l’obtention d’une particule hybride constituée d’un cœur de boehmite et d’une couche polymérique. En réalité, le greffage d’organosilane à la surface permet de créer un pont entre la partie centrale inorganique et la partie externe organique constituée de latex pouvant se lier à l’organosilane utilisé (le MPS).Le matériau hybride boehmite-MPS-latex ainsi obtenu peut être utilisé dans une nouvelle technique de mise en forme colloïdale inspirée de la granulation par hétérocoagulation. En milieu aqueux, la polarité opposée des charges de surfaces de deux entités différentes conduit à l’hétérocoagulation en suspension. La coagulation observée dans cette thèse, met en relation deux particules identiques possédant chacune, les deux charges opposées à leur surface. Le principe de la granulation consiste à induire, sous l’effet d’un mouvement de rotation des échantillons, la coalescence des agglomérats en forçant leurs surfaces à interagir par contacts réciproques. En sélectionnant la formulation, la coalescence conduit à l'élaboration d'objets sphériques homogènes en taille et en forme. / Research in this field is multidisciplinary and relies largely on the development of nanomaterials. These are, in fact, the raw materials of nanoscience and open to industry extremely broad prospects. In the field of material sciences, nanostructured materials, among them nanostructured ceramics have grown considerably in recent years. Development of ceramic requires a mastery of production processes that achieve appropriate microstructures in the development of dense materials for various applications such biomédicals. Recent developments include hybrid and bio-inspired materials; the problems of shaping and multi-scale structure of these encourage the development of new processes such as the new so-called bottom-up approach of manufacturing and make macroscopic material from its nanoparticles. In this context, the work of this PhD aim to facilitate, through surface modification, the development of an original layout technique for the development of ceramics from a material nano-oxide type: granulation coagulation. We were interested in the case of a boehmite nanopowder (AlO(OH)). However, this nanoscale boehmite powder has many instabilities in suspension. Indeed, the powder is subjected to strong gelation as function of pH and at low concentrations. It is necessary in this case to obtain a stable suspension by modifying the surface properties. Accordingly, a part of this work is devoted to surface functionalization by organosilanes. This surface modification, however, is only one stage to obtain a hybrid particle comprised of a heart of boehmite and a polymeric layer. In reality, the grafting organosilane (MPS) at the surface permit to create a bridge between the inorganic core and organic outer part consists of latex. The boehmite-MPS-latex hybrid material thus obtained can be used in a new colloidal shaping technique inspired by heterocoagulation granulation. In aqueous medium, the opposite polarity of the charges of the surfaces of two different entities leads to heterocoagulation in suspension. Clotting observed in this thesis, connects two identical particles with each, the two charges opposite to the surface. The principle of the granulation is to induce, under the effect the rotational movement, the coalescence of the agglomerates by forcing their surfaces to interact by mutual contact. By selecting the formulation, coalescence leads to the development of homogeneous spherical objects in size and shape.
37

Coagulation and size fractionation studies on pulp and paper mill process and wastewater streams

Leiviskä, T. (Tiina) 05 January 2010 (has links)
Abstract This thesis aims to increase our knowledge about the characteristics of chemical pulp process and wastewaters and how problematic substances, e.g. wood extractives, could be removed effectively and selectively by coagulation–flocculation with either internal or external water treatment. Characterization was performed by investigating kraft pulp bleaching filtrates, as well as wastewater, before (influent) and after (effluent) the activated sludge treatment by means of a range of chemical analyses and by carrying out size fractionation studies. Cationic polyelectrolytes were used to purify oxygen stage bleaching filtrate, and charge analyses (zeta potential, charge quantity) were carried out in order to understand the coagulation phenomenon. In activated sludge treatment, the enhancement of particle removal, either by filtration or using a chemical in the primary clarifier, would lead to savings in aeration costs and result in a more stable process. Microfiltration already with a large pore size (8 µm) removed 30–50% of the wood extractives from the influent. Separate treatment stages for certain wastewater fractions, e.g. debarking plant effluent, would ensure cost-efficiency. After the activated sludge process, the wood extractives were present as particles (18%) and < 3 kDa fraction (82%). β-sitosterol occurred only in particles in the effluent. The release of harmful components into the environment could be decreased by microfiltration (e.g. 0.45 µm) of the final effluent or using a chemical in the secondary clarifier. Interestingly a huge increase in BOD was realized in the 3 kDa fraction of both influent and effluent, which indicated the presence of toxic substances in the larger fractions. After passing the effluent into the water system, there might be a similar jump in the BOD because the effluent is diluted many-fold. This would contribute to the formation of areas with an oxygen deficit. In the coagulation–flocculation studies, effective and selective removal of wood extractives (92%) from the oxygen stage filtrate was obtained with a cationic polyelectrolyte of medium molecular weight and medium charge density at 72 °C and pH 5–6. The multimodal zeta potential distribution gave more information than the average zeta potential. Aggregation of colloidal particles occurred when only one zeta potential was observed. The number of different zeta potentials diminished with decreasing pH and after exceeding a certain polyelectrolyte dosage level.
38

Novel interfacial adsorption properties of collagenous polypeptides and their interactions with model surfactants

Rodriguez Rius, Maria Angeles January 2013 (has links)
The interfacial adsorption and bulk properties of a collagenous polypeptide derived from chicken eggshell membranes, the 40 KDa polypeptide, and its mixtures with common low molecular weight (LMW) surfactants, SDS, DTAB and C10E8, have been studied for the first time using surface tension, ζ-potential, foam observations and neutron scattering techniques. The biopolymer has been shown to act as an effective biosurfactant by lowering the surface tension of water below the values commonly achieved with conventional LMW surfactants, i.e. γ = 32 ± 1 mN/m. This capability is maximized at its isoelectric point, pH ~5, and addition of NaCl does not have a major impact upon adsorption. On its own, the 40 KDa polypeptide lacks the ability to foam. When mixed with cationic and anionic surfactants, a positive synergy is observed at low concentrations of both materials that exceeds the expectations from the individual components due to the formation of polypeptide/surfactant complexes with high surface activity and high ability to foam and foam stability. At these concentrations, maximum interfacial adsorption is achieved. The synergy is observed in spite of the type of charges present in the surfactant polar head. However, under the conditions studied, there is a difference in behaviour in regards to colloidal stability and surface film formation between the mixed solutions with the anionic SDS and the cationic DTAB. The non-existence of the synergy in the surface adsorption profile of the mixtures of the polypeptide with the non-ionic surfactant C10E8, as obtained via the plate method, suggests that electrostatic interactions are necessary for this strong synergy to act. ζ-potential has been used to prove the electrostatic nature of the synergy. Specular neutron reflection and SANS measurements offered an insight into the complex size and structure. The 40 KDa polypeptide thus offers a promising alternative to the use of high amounts of LMW surfactants in a range of products in which low surface tension and/or high and stable volumes of foams are needed, by combining small amounts of polypeptide and an ionic surfactant. This could be exploited by industries which have an interest in nanoparticle formation such as personal care or pharmaceutical companies. However, further work is needed to fully characterize these interactions.
39

Noncovalent Functionalization of Latex Particles using High Molecular Weight Surfactant for High-Performance Coatings

Zheng, Lei 20 August 2019 (has links)
The expected outcome of this project is to develop a general strategy to functionalize dispersions, by noncovalent adsorption of HMW surfactants, ultimately for applications such as hydrophobic coatings with high hiding power and hardness, improved mechanical properties via pigment-latex interactions, improved substrate adhesion or improved freeze-thaw stability. So far, we have produced poly (methyl methacrylate-co-butyl acrylate) latexes in the presence of HMW surfactants via emulsion polymerization and demonstrated stronger adsorption of HMW surfactants on particle surface than sodium dodecyl sulfate (SDS). In addition, we have developed surfactant-free latexes, poly (methyl methacrylate-co-butyl acrylate-co-methacrylic acid), as models for post functionalization with high molecular weight surfactants. The successful transfer of surfactants onto particle surface from liquid crystals was indicated by the increase in zeta potential and confirmed via chemical shifts variation in 1H NMR spectra. Additionally, the HMW surfactants were used for dispersing hydrophobic inorganic particles, such as hydrophobic carbon black, in aqueous phase, providing an indication of the general applicability and versatility of our approach.
40

Vysokohodnotné síranové pojivo na bázi odpadních surovin / Waste material based high-performance sulphate binders

Hájková, Iveta Unknown Date (has links)
The topic of this dissertation was the preparation of a high-quality sulphate binder based on secondary raw materials. For this purpose, the work was primarily focused on the laboratory preparation of beta gypsum from the selected industrial gypsum, the design of the technological process of production and its verification by pilot tests. In the next step, the thesis dealt with the modification of beta gypsum by a selected set of liquefiers. In addition to commercial dehumidifiers, the possible beta casting of beta gypsum was tested by increasing the zeta potential of the gypsum suspension. At the end, a complete complex of construction products was developed based on laboratory and semi-prepared beta plasters, consisting of gypsum plasters, mastics, gypsum premix and small plaster casts.

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