Dissertations / Theses on the topic 'Talc'
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1
Arnoux, Francis, and Bernard Majza. "Contribution à l'étude géologique des gisements de talc du massif du Saint-Barthélémy (Ariège)." Université de Franche-Comté. UFR des sciences et techniques, 1986. http://www.theses.fr/1986BESA4000.
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Gallego, Jean-Christophe. "Elaboration d'hybrides organiques-inorganiques de structure de type phyllosilicate 2:1 et leurs applications." Mulhouse, 2008. http://www.theses.fr/2008MULH2999.
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Cette thèse décrit la synthèse et l'étude d'hybrides organique-inorganiques de type talc. La synthèse dont est inspiré ce travail a été décrite pour la première fois par Fukushima & Tani en 1995. Celle-ci est particulièrement attractive du fait des conditions de synthèse douce. Ainsi ce travail décrit la recherche des conditions optimales de synthèse sur l'exemple su N-phénylaminométhyl - TLH. Par la suite, nous décrivons la synthèse d'une large série d'hybrides organiques-inorganiques de structure de type talc. De nombreuses techniques de caractérisation sont ensuite employées pour décrire précisément la structure de ces matériaux. Enfin, le dernier chapitre illustre l'application comme renfort de ces matériaux hybridesThis thesis describes the synthesis and study of organic-inorganic talc like hybrid. The synthesis is inspired frome the work of Fukushima & Tani in 1995. This synthesis is particularly attractive because of soft conditions. Thus this work describes the search for optimum conditions of synthesis on the example N- phenylaminomethyl - TLH. Subsequently, we describe the synthesis of a wide range of organic-inorganic talc like hybrid. Many characterization techniques are then used to precisely describe the structure of these materials. The last chapter illustrates the application as a reinforcement of these hybrid materials
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Khan, Shahid Wahab. "Rheological properties of talc-filled polypropylene." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/7567.
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In this study polypropylene was modified by a range of talc (Mg3(OH)2Si4OlO) fillers. Three different types of surface modifiers were also used, two types of silanes (octyltriethoxysilane and y-aminopropyltriethoxysilane) and maleic anhydride modified polypropylene plus polyethylene wax as an external lubricant. A series of compounds were prepared in an APV twin screw compounder, based on talc addition level, morphology, particle size, surface coatings and coupling agents. The study showed that addition of talc to PP increases the shear viscosity and the blend system generally follows the power law in the shear rate range studied. The experimental values obtained with talc-filled PP were compared with theoretical data obtained from the Maron-Pierce type equation. It was found that theory predicts a higher value of relative viscosity for some talc fillers. A model equation is proposed for talc-filled PP that predicts accurately relative viscosity of the compound for different volume fractions of talc filler. PP-filled with talc having predominantly acicular particles (high surface area), shows a highest shear viscosity values, since high surface area fillers tend to increase the occluded polymer increasing the effective filler volume. The addition of a high level of coating decreasess hearv iscosity of the system,a ddition of a reactivec oupling systems lightly increasess hearv iscosity. Wall slip for unfilled PP was consistently evident. The slip velocity increases systematically with shear stress, but there is a critical value below which slip velocity was negligible. Addition of talc decreased the slip velocity at a given stress. A mechanism of slip has been proposed whereby a 'slip layer' on the die surface provides a sharp, low energy interface over which, at sufficiently high shear stress, the fluid PP can slip. A new empirical model has been proposed to predict the slip velocity of filled PP, as a function of talc volume fraction. PP filled with 10 % wt. talc having predominantly acicular particles, showed a higher slip velocity than PP filled with talc of other morphologies. It was observed that slip velocity increased by coating talc (either by use of coating or coupling agents) due to modification of velocity distributions in the flow channel. Extrudate swell increases with increasing shear rate for unfilled and talc-filled PP compounds. Inclusion of talc generally decreases the swell over the entire range of shearr ates studied,b ecauset he addition of talc to PP increasesth e shear/extensional modulus and thereby decreasede lastic strain recovery. No appreciablei nfluence of particle size on swell ratio was observed. Coating talc with octyltriethoxysilane produces higher swell relative to uncoated filled PP, and higher coating levels consistently produced higher swell values. However, coupling agent 7- aminopropyltriethoxsilane and maleic anhydride modified polypropylene both reduced the swell of the filled polymer system, with a more pronounced effect in extension than in shear. Swell decreased with an increase in capillary length-todiameter ratio and increased with increase in shear rate, (or shear stress) with or without coating/coupling agent. Addition of talc fillers delayed the onset of melt fracture and higher loadings of talc completely suppressed the melt fracture in the range of shear rate studied. Melt fracture for unfilled and filled PP has been studied and quantified by the frequency of the melt distortion. A mechanism for polymer melt fracture has been proposed to explain the results, based on the tensile failure of the material in extensional deformation. It was found that shear rate and die L/D ratio were the major causes of changesin severity of melt fracture for the unfilled and talc-filled compoundss tudied. However, talc morphology and particle size did not have significant effects on the severity of melt fracture.
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Amorim, Camila Almeida. "Efeitos da radiação ionizante nas propriedades de compósitos de poliamida 6 com dióxido de silício coloidal (AEROSIL®)." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-07122017-094709/.
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Os polímeros têm sido usados em áreas diferentes, como indústrias automotivas, eletrônicas e de construção civil. A poliamida 6 (PA 6) é um dos principais plásticos de engenharia com aplicações em diversas áreas produtivas, devido as suas propriedades térmicas, mecânicas e a estabilidade dimensional. O objetivo principal deste trabalho foi estudar a potencialidade do uso do dióxido de silício coloidal (SiO2) como carga em substituição ao talco, estudando o efeito da radiação ionizante em suas propriedades. O SiO2 é uma substância amorfa com baixa densidade que tem potencial para ser usado como carga mineral em substituição ao talco na matriz da resina de PA 6. Atualmente o talco é a carga mineral mais utilizada pelas indústrias, por isto vem sofrendo redução de suas reservas ao longo dos anos. Este estudo foi desenvolvido a partir da preparação de um \"masterbeach\" de PA 6 com SiO2. Posteriormente, este \"masterbeach\" foi fracionado em diferentes porcentagens em uma matriz de PA 6. Os corpos de prova das amostras foram processados em uma extrusora dupla rosca, injetados e irradiados no acelerador de elétrons para estudar o efeito da radiação ionizante no compósito de PA 6 com diferentes porcentagens de SiO2. Assim sendo, as propriedades destes compósitos foram analisadas e comparadas com as propriedades das amostras de PA6 com talco. Os resultados mostraram que a utilização do SiO2 como carga para a poliamida 6 é tecnicamente viável, uma vez que suas propriedades foram semelhantes ao compósito de PA 6 com talco. A irradiação dos compósitos estudados apresentou melhorias principalmente nas propriedades térmicas e mecânicas.Polymers have been used in different fields, such as automotive, civil construction and electronics industries. Polyamide 6 (PA 6) is one of the main engineering plastics with several productive applications areas. By the same token, there was an interest in improving their thermal, mechanical and dimensional stability properties. The main objective of this work was to study the potentiality of colloidal silicon dioxide such as filler. According to literature, SiO2 is an amorphous substance with low density. In addition, this material has the potential to be used as a mineral filler to replace the talc in the PA 6 resin matrix. Therefore, SiO2 load was compared to the mineral filler talc which is currently used by industries. Consequently, their reservations are decreasing all over the years. Indeed, these studies were developed from colloidal silicon dioxide with PA 6 the masterbatch elaboration. In addition, the masterbatch was fractionated in different percentages in a PA 6 matrix. It is important to emphasize that all samples were injected and irradiated by an electrons accelerator. Furthermore, the effect of ionizing radiation on the PA 6 composite in different SiO2 percentages was studied. In short, radiation interacts with the polymer by transferring energy to a polymer chain causing modifications that are interfering with its properties. Thus, the mechanical and thermal properties of these composites were measured. In this manner, the irradiation composite studied in that research brought improvements in the thermal and mechanical properties evaluated. In conclusion, results have shown that the use of colloidal silicon dioxide in polyamide 6 composite is technically feasible load to replace talc.
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Fiorentino, Brice. "Orientation cristalline de la matrice résultant de la déformation et des charges lamellaires dans des nanocomposites thermoplastiques." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10241.
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Cette étude s’inscrit dans le projet ANR Blanc COPIN qui a pour but de développer et de comprendre les nanocomposites à partir de nanoparticules inorganiques mélangées à un polymère semi-cristallin. L’innovation du partenaire du projet, Imerys, a été de synthétiser des particules de talcs à l’échelle nanométrique. Le talc étant connu pour ces effets nucléants, l’objectif est d’utiliser ces nanoparticules pour voir leur influence sur un matériau semi-cristallin et plus spécifiquement sur la cristallisation de ce dernier lorsqu’elles sont orientées. Différents talcs synthétiques ont été étudiés changeant au niveau de leur durée de synthèse ou encore de leur modification de surface. Pour cela, la première partie de cette étude a été de disperser le talc en utilisant ou non des modifications chimiques de surface ainsi que des compatibilisants afin d’obtenir le meilleur état de dispersion et de distribution des particules. Ces continuums d’interactions ainsi créés montrent une nette amélioration de l’état de dispersion mais aussi l’amélioration des propriétés telles que la tenue en température. Les parties suivantes ont concernées plus spécifiquement la cristallisation en convoitant d’expliquer comment les nanoparticules peuvent s’orienter lors de l’écoulement tel que le cisaillement, comment elles génèrent une orientation cristalline spécifique du à leur effet nucléant, quel est le mécanisme prépondérant de la cristallisation entre la nucléation par l’orientation de macromolécules ou la nucléation provenant des nanoparticules. Il a aussi été question de déterminer les morphologies cristallines des nanocomposites lors du cisaillementThis study is part of the ANR Blanc COPIN which aim is to develop and understand the nanocomposites from inorganic nanoparticles mixed with a semi-crystalline polymer. The innovation of the project partner, Imerys, was to synthesized talc particles at the nanoscale. Talc is known for his nucleating effects and the goal is to use these nanoparticles to see their influence on a semi-crystalline material. Several synthetic talcs were employed differing from the synthesis time and chemical surface modifications. For this, the first part of this study was to disperse the talc using or not chemical modifications of surfaces as well as compatibilizers to obtained the best dispersion state and particles distribution. These continuums interaction created show a real improvement in the dispersion but also of properties such as heat resistance. The following parties concerned more specifically the crystallization trying to explain how nanoparticles can be oriented during shear flow, what is the leverage of these talcs on the crystallization when it was oriented, how they generate a specific crystal orientation coming from their nucleating effect, which is the predominant mechanism of crystallization nucleation between the macromolecules orientations or the nucleation of nanoparticles. It was also a question of determining the resulting crystal morphologies
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Godfroy, Patrice. "Performance des mélanges polypropylène/talc/polyéthylène-octène." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0006/MQ42908.pdf.
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Godet, Laurence. "Broyage fin du talc par jets d'air opposés." Vandoeuvre-les-Nancy, INPL, 2001. http://www.theses.fr/2001INPL042N.
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Le talc est un minerai largement employé dans les industries des peintures, des polymères, du papier, de la céramique et des cosmétiques. Extrait des carrières, il doit être ftagmenté par différents broyeurs pour atteindre la distribution de tailles désirée et adaptée à son utilisation. Afin d'obtenir des particules microniques d'une haute pureté dont la distribution de tailles est resserrée, le. Talc est broyé sans contamination par jets d'air opposés et classifié par un classificateur pneumatique dans des broyeurs de type Alpine AFG. La stabilité de la distribution de tailles des particules pendant le procédé de broyage peut être suivie en direct en installant un granulomètre laser en ligne. Dans le cas du talc, le montage du graoulomètre laser s'effectue en dérivation de façon à disperser les particules de talc pour pouvoir suivre l'évolution de la taille lors de l'établissement du régime permanent. Lors du broyage en continu du talc par jets d'air opposés avec une vitesse de classification fixée, l'augmentation du débit d'alimentation conduit inéluctablement à l'engorgement, ce qui se traduit par l'augmentation de la taille du produit et une instabilité du régime du broyeur. Pour chaque vitesse de rotation du classificateur, il existe un débit d'alimentation optimal et donc une masse retenue optimale dans le broyeur permettant d'obtenir la plus grande finesse du produit. Par ailleurs, des essais en mode discontinu permettent de déterminer l'influence de la masse retenue dans le broyeur sur le broyage et sur les paramètres de broyage du talc. Ainsi, à partir de la fonction de sélection obtenue, il est possible de calculer la fonction de broyage, indicatrice du fragmentation du talc. Enfin, les courbes de partage du classificateur pour les différentes vitesses de classification sont utilisées dans la modélisation globale du procédé de broyage-classification. Il semble que les chaînes de Markov conviennent pour modéliser le régime permanent du procédé.
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AOUN, SALIM. "Biocatalyses avec l' chymotrypsine et la chloroperoxydase en milieu micellaire et supportees sur talc : interet de l'adsorption sur le talc." Toulouse 3, 1998. http://www.theses.fr/1998TOU30132.
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Au cours de cette etude, nous avons evalue les capacites catalytiques de deux enzymes, une protease l' chymotrypsine et une haloperoxydase la chloroperoxydase, en milieu micellaire et adsorbees sur des surfaces talqueuses. Au cours du premier chapitre, un rappel bibliographique a ete realise afin de mettre en evidence le role que peut jouer la structuration d'un milieu micellaire, a partir des reactivites de l' chymotrypsine et la chloroperoxydase. Nous avons decrit egalement l'influence de l'adsorption d'enzymes sur des supports solides, et compare les differents modes d'immobilisation. Un support original le talc sera presente. Dans le deuxieme chapitre, une etude de la reactivite de l' chymotrypsine a travers l'esterification d'un acide amine (n acetyl-l-tyrosine) dans un milieu micellaire constitue d'octanol-2, d'aot et de tampon a ete developpee. L'originalite de ce milieu se situe au niveau de la phase huileuse qui est en meme temps constituant de la microemulsion et nucleophile de la reaction enzymatique. Malheureusement, l'extension de ce processus d'esterification a la resolution d'alcools racemiques s'est averee negative. La chloroperxydase a ete egalement incorporee dans deux systemes micellaires differents afin d'evaluer ses capacites catalytiques. En absence d'ion halogenure, l'epoxydation d'alcenes n'est pas concluante car peu selective. Par contre, en presence d'ion bromure, l'halohydroxylation est quantitative et regioselective contrairement aux resultats obtenus en milieu aqueux. Enfin dans un dernier chapitre, nous avons etudie les interactions de la chloroperoxydase et de divers minerais de talc en vue d'obtenir des couples cpo-talc comme biocatalyseurs solides d'interet industriel. Nos divers travaux ont permis de montrer le role protecteur de certaines varietes de talc vis a vis de la chloroperoxydase. Une amelioration dans le processus d'halohydroxylation d'alcenes, notamment par l'accroissement des quantites de substrat et d'oxydant entrant en reaction, a ete proposee. Les mecanismes de ces biocatalyses, encore incertains, sont discutes et nos resultats s'inscrivent dans leur meilleure comprehension.
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Michot, Laurent. "Propriétés physicochimiques superficielles du talc et de la chlorite." Vandoeuvre-les-Nancy, INPL, 1990. http://www.theses.fr/1990INPL073N.
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Après avoir défini les produits de départ, on étudie les propriétés texturales, superficielles, structurales et rhéologiques de produits obtenus après broyage humide en présence de divers adjuvants organiques ou minéraux. L'analyse statistique des résultats se révèle discriminante vis-à-vis du milieu de broyage et du brut de départ mais ne permet pas d'établir de modèles d'évolution des paramètres. Une étude de l'évolution de la charge superficielle à l'aide de la micro électrophorèse et de la spectrométrie IRTF en réflexion diffuse permet de proposer un modèle représentant la surface du talc. L'évolution des propriétés texturales et structurales en fonction de l'intensité du broyage est étudiée. On s'intéresse également aux propriétés d'application des différents échantillons comme charge dans un polypropylène. Par analyse statistique, on est alors capable de proposer un modèle reliant les caractéristiques d'application à un certain nombre de paramètres physicochimiques aisément mesurables en laboratoire. On utilise une large batterie de techniques d'absorption de différents gaz simples à la surface du talc et de la chlorite. On observe une très forte affinité de l'azote pour la surface du talc. L'étude par spectrométrie de masse des espèces dégagées lors du dégazage du talc tend à montrer la présence en surface d'espèces azotées fortement liées. L'ensemble de ces résultats permet de proposer une nouvelle explication à l'hydrophobie naturelle du talc
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Karrad, Sahnoune. "Mélanges composites PEHD/PS/Talc : application au recyclage." Montpellier 2, 1995. http://www.theses.fr/1995MON20036.
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Temnov, D. E., and E. E. Fomicheva. "Electret Properties of Polyethylene Composite Films with Talc." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35636.
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The electret properties of polyethylene films with nanodimensional particles of talc have been investigated.
The stable of electret state of polyethylene was improved with the addition of talc. This result can be
explained by the fact that hydroxyl groups, which absorbs water, are locate on the peripheral area of talc
particles. Accordingly, number water molecules in the polymer volume become less, and, therefore, the
conductivity of a material should be decrease, and the stability of the electrets state should be increase.
The adding of talc in polyethylene leads to a new relaxation process, that it is visible on the spectra
thermally stimulated depolarization. The peak in this area can be associated with the process of accumulation
and relaxation of charge on the border of phases of polymer-filler.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35636
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Richard, Alain. "Automatisation d'une unité industrielle de séchage de talc." Grenoble : ANRT, 1985. http://catalogue.bnf.fr/ark:/12148/cb37595124j.
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Dumas, Angela. "Élaboration de nouveaux procédés de synthèse et caractérisation de talcs sub-microniques : de la recherche fondamentale vers des applications industrielles." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/3999/.
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Cette thèse s'inscrit dans le processus général d'innovation dans le domaine des matériaux composites. Financée par le projet ANR NANOTALC, elle a permis de réaliser des avancées considérables dans la procédure de production de nouvelles nanocharges minérales de type talc. Le procédé de synthèse du talc a été revisité dans le but de le rendre compatible avec des exigences industrielles en termes de rendement et d'efficacité. Ce procédé supplante les précédents en ce qu'il permet l'obtention d'un produit 100% talc avec un gain de temps et un gain de cristallinité tout en respectant quelques principes de la chimie verte. La caractérisation cristallochimique du nouveau talc synthétique a permis l'obtention de nouvelles signatures spectrales liées aux dimensions submicroniques, qui permettent par ailleurs de comprendre désormais certains comportements énigmatiques de poudres naturelles. Le talc synthétique issu de ce nouveau procédé se distingue de son homologue naturel par sa taille submicronique, sa pureté chimique et minérale mais aussi par son caractère hydrophile, caractère amplifié par l'abondance de bordures latérales porteuses de fonction silanols. Cette thèse retrace aussi les différentes techniques testées pour optimiser ce procédé et propose une nouvelle solution technique pour transposer la synthèse à une échelle semi-industrielleThis thesis takes part of the general process of innovation in the domain of composite materials. The funding by the ANR NANOTALC project allowed significant progress in the process of production of new talc-like mineral nanofillers. The talc synthesis process has been revised in order to achieve compatibility with industrial requirements in terms of performance and efficiency. This new process replaces the previous ones since it saves time, leads to a 100% talc product having a high crystallinity, in the respect of few principles of the green chemistry. The crystal-chemistry characterization of the new synthetic talc shows new spectral signatures related to nanoscale dimensions, which allow also understanding of some until now unexplained behavior of natural powders. The synthetic talc derived from this new process differs from its natural counterpart in its submicron size, its chemical and mineral purity and also in its hydrophilic character, which is enhanced by the abundance of particle edges bearing silanol functions. This thesis also describes the various techniques tested to optimize this process and provides a new technical solution for the implementation of the synthesis on a semi-industrial scale
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Yang, Song. "Épuration de minéraux silicatés : talcs de la société Talc de Luzenac : mécanisme de la flottation différentielle chlorite-dolomite-quartz." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL056N.
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L’objectif est de rechercher les moyens de valorisation de rejets talqueux ou de mélange de talc et de chlorite contenant de la dolomite ou du quartz. L’hydrophobicité naturelle du talc permet d'obtenir par flottation des concentrés enrichis en talc. Les résidus de cette opération contenant du talc, de la chlorite, de la dolomite, et du quartz sont commercialisable si l'on est capable d'éliminer les carbonates et le quartz. Cette séparation a été étudiée sur des phases pures en tube Hallimond et en micro cellule EMDEE. La mesure des temps d'induction et les résultats sur phases pures ont permis de définir les conditions optimales de flottation. Des essais en cellule de laboratoire ont confirmé les conclusions obtenues. Une étude plus fondamentale des phénomènes mis en jeu a été effectuée à partir de propriétés superficielles des phases pures et par l'étude de l'adsorption des différents réactifs
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Beuguel, Quentin. "Systèmes multiphasiques à base de nanoparticules de talc synthétique : relations procédé - structure - rhéologie." Thesis, Brest, 2015. http://www.theses.fr/2015BRES0046/document.
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L’incorporation de nanoplaquettes d’argile dans une matrice ou un mélange de thermoplastiques s’avère prometteur pour en améliorer les propriétés d’usage. Récemment, un procédé de synthèse hydrothermale a permis d’obtenir un hydrogel chargé de nanoplaquettes de talc, ouvrant des perspectives d’élaboration de nanomatériaux à base de talc, potentiellement concurrents de ceux à base d’argile modifié. La grande quantité d’eau, introduite dans les appareils de mise en œuvre à l’état fondu, conduit à une perte de matière minérale importante et à l’agrégation partielle du talc. Ces contraintes rendent obligatoire l’utilisation de la mini-extrudeuse, de faible capacité, pour élaborer ces systèmes multiphasiques innovants, comme les nanocomposites polyamide/talc synthétique ou les mélanges polypropylène/polyamide (PP/PA) chargés de talc synthétique. Dans une phase polaire, le talc synthétique présente une structure constituée majoritairement de nanoparticules, mais aussi d’agrégats formés lors du malaxage. Il a été montré qu’une polarité accrue de la phase polyamide facilitait la nanodispersion du talc synthétique. Dans le cas des mélanges chargés, le talc synthétique est préférentiellement localisé dans les nodules de PA. Pour un polyamide peu polaire, l’effet émulsifiant est amplifié, ce qui s’explique par la rupture des nodules au niveau de zones peu cohésives PA/talc synthétique. D’autre part, l’augmentation de la viscosité de la matrice PP entraîne une localisation partielle du talc synthétique à l’interface matrice/nodules.Les relations structure-rhéologie des systèmes binaires et ternaires ont été discutéesAddition of clay nanoplatelets within a thermoplastic matrix or immiscible thermoplastic blend usually improves final properties of materials. Recently, a hydrogel containing talc nanoplatelets has been obtained from hydrothermal synthesis, opening possibilities of development of talc based nanomaterials, which could rival the nanocomposites based on organically modified clay.The presence of large amount of water in the mixing chamber leads to significant losses of inorganic matter and to the presence of a few synthetic talc aggregates. These observations require the use of a twin screw mini-extruder which is appropriate to the elaboration of innovative multiphase materials, such as the synthetic talc/polyamide nanocomposites or the synthetic talc/polyamide/polypropylene blends.The structure of nanocomposites based on synthetic talc is mainly composed of nanometric entities, but also of a few micrometric aggregates. It has been shown that an increase of the polarity of the polyamide favours the dispersion of synthetic talc at nanometric scale.In the case of filled blends, the synthetic talc particles are preferentially located within PA nodules. The reduction of nodule size is explained by the breakup of nodules, due to numerous cohesion defects between synthetic talc nanoparticles and polyamide dispersed phase. Moreover, increasing polypropylene matrix viscosity leads to a selective localization of the synthetic talc at the nodule/matrix interface.Relationships between structure and rheology of binary and ternary systems have been discussed
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Venables, Richard Anthony. "Structure and properties of alkyltrimethoxysilane modified talc/polypropylene composites." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/10557.
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Ellis, Amy Clare. "The effect of hydrothermally generated talc upon fault strength." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/the-effect-of-hydrothermally-generated-talc-upon-fault-strength(f77b9984-f170-4fc0-86c4-9a23e9f158d4).html.
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At present there is no theory which describes fully observations of weakness and anomalous slip behaviour on many faults. Recent field studies upon such faults indicate that reactions which generate frictionally weak phyllosilicate minerals, including talc, may be significant. A series of experiments was carried out on a deionised water fluid medium triaxial deformation apparatus to investigate the effect of the syntectonic generation of talc upon fault strength and slip characteristics, where talc is produced by the reaction: lizardite + quartz → talc + H2O. Experiments to investigate reaction kinetics were performed on lizardite and Brazilian quartz powder samples. Talc is generated by this reaction within 72 hours under hydrothermal conditions between 350°C and 500°C and effective pressures of 5 to 50 MPa. Microstructural study shows porous talc overgrowths surrounding lizardite and quartz grains suggesting an armouring effect with progressive reaction. Constant displacement rate tests and subsequent stress relaxation tests were performed upon cylindrical samples of lizardite and Hodge quartzite saw-cut at 35° juxtaposed across the shear zone. Some samples were assembled with pure talc or lizardite gouge between the forcing blocks. Tests were carried out under hydrothermal conditions: 450 °C, 50 to 150 MPa effective pressure and 4.64 x 10-4 mm s-1 shear surface displacement rate. Some samples were deformed at once to assess frictional properties of the starting materials. Other samples were held at hydrothermal conditions for 72 hours prior to deformation, to allow the blocks and gouge to react to talc. Continued reaction to talc was expected during stress relaxation. All samples displayed stable sliding behaviour, with little strain hardening. Friction coefficients averaged from varied effective pressure tests were largely in line with previous studies. A strength contrast is shown between talc gouge (average µ=0.11) and talc grown as a thin veneer between lizardite and quartz forcing blocks, (average µ=0.22) which is likely to be due to asperity effects including the variable contiguity of the talc veneer. Lizardite gouge gives a value of µ=0.45, but when partially reacted to talc gives µ=0.23. This is significantly weaker despite representing perhaps less than 15% talc. Stress relaxation data initially shows similar behaviour for all sample geometries, with a temperature-controlled dominant deformation mechanism. Lizardite gouge with ongoing reaction to talc shows enhanced shear stress reduction at low strain rates (stress exponent falls from n=12 to n=5.5). This is ascribed to the effect of reaction via production of a weaker phase, leading to reduction of frictional strength and grain size, compaction and pressure solution effects. Pure lizardite gouge also shows a reduction in stress exponent to n=7.5, attributed to dissolution-precipitation of lizardite. Microstructural study shows that talc grows as a thin veneer along the quartzite forcing block indicative of localisation of deformation with foliated talc and recrystallised lizardite present within Riedel shear structures in the lizardite gouge. The talc veneers are deformed and may be subject to mechanical smearing, enhancing their contiguity. Results of this study highlight the significance of both mechanical smearing and incongruent pressure solution creep as potential mechanisms for weakening and aseismic creep-of particular interest is the rate of strength reduction versus the rate of reaction and whether this can be extrapolated fully to creep rates on the San Andreas Fault. Similar weak phases of hydrothermal origin have been identified by other studies and the contiguity of these phases is thought crucial to their impact upon weakness, and may be enhanced greatly by the joint effects of syntectonic reaction and mechanical smearing.
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Hauptstein, Anneliese Materials Science & Engineering Faculty of Science UNSW. "The effects of electron irradiation on the morphology, modification and microstructure of talc powder." Awarded by:University of New South Wales. School of Materials Science and Engineering, 2007. http://handle.unsw.edu.au/1959.4/27303.
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Electron irradiation may be a useful method for treating inorganic cosmetic powders such as talc for undesirable microorganisms if it can be established that no loss of quality or efficacy results as a consequence of the technique. A commercial electron accelerator was used to prepare bulk samples by exposure to electron irradiation under different conditions. A morphological characterisation of the control talc was carried out using microscopy techniques and focused on the particle size, shape and surface features of individual particles. Asperity dimensions vs. Roughness values were compared. Assessment of the bulk properties of the powders as a function of absorbed dose showed no serious impact on the quality or efficacy of the powder for cosmetic applications. The particle size and the level of dust expelled during impact were maintained. Changes to the surface chemistry of the irradiated powders were apparent from an increase in pH and water retention with increasing dose. Improvements to the fragrance retention occurred for both irradiated powders tested. Importantly a satisfactory microorganism level was achieved with the lowest absorbed dose level tested i.e. 5 kGy. Analysis of the crystallography did not show the development of a new phase. Mechanical testing using a slip-peel tester found an increase in the stick-slip behaviour occurred for the powder exposed to the highest absorbed dose only. Atomic force microscopy (AFM) testing of the lift-off force showed an increase in adhesion with increasing dose. Surface roughness increased with dose, while no change in elastic properties was found using nanoindentation suggesting the differentiating factor is due to surface features. Microstructural analysis used the transmission electron microscope (TEM). Voids were observed, which decrease in size, yet increase in number with increasing voltage. Prior to void development a loss of crystalinity is seen using electron diffraction. Explorative data analysis using factor analysis and Independent Component Analysis was performed on the void development data to discover the controlling mechanisms. Two distinct normally distributed populations were identified, each driven by 2-3 critical mechanisms. The distinct behaviour differences of the mechanisms may be utilised for characterisation of more complex properties of crystal microstructures.
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Gil, Medina Eva Maria. "Alignment and management of talc platelets in polypropylene matrix by the application of Shear Controlled Orientation Injection Moulding (SCORIM) technology." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309497.
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Oliveira, Pedro Paulo Martins de 1968. "Uso de membrana de poli (alcool vinilico) - PVAI como substituto pericardico : trabalho experimental." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/311521.
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Orientador: Orlando Petrucci JuniorTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: Introdução: Reoperações representam cerca de 20% das cirurgias cardíacas, quase na totalidade com esternotomia, onde há a formação de aderências entre o coração, esterno e estruturas adjacentes. Lesões das câmaras cardíacas e grandes vasos pela serra esternal ou na dissecção dessas estruturas resultam em aumento da morbimortalidade e do sangramento perioperatório. Vários autores propuseram o uso de substitutos pericárdicos biológicos e sintéticos na tentativa de diminuir o risco de acidentes nas reoperações, porém sem resultados consistentes em longo prazo. A membrana de poli (álcool vinílico) - PVAl reticulado formam um hidrogel bastante estudado como biomaterial, com boa biocompatibilidade e características favoráveis ao seu emprego como substituto pericárdico. Objetivo: Caracterizar a membrana de PVAl quanto à capacidade de absorção de água, calcificação e citotoxidade e estudar o comportamento biológico da mesma como substituto pericárdico. Metodologia: Foram utilizadas amostras da membrana de PVAl reticulada por irradiação e realizados ensaios de citotoxicidade em culturas de células VERO, da capacidade de absorção de água e de calcificação após o implante in vivo. Ratos da Raça Wistar foram divididos em quatro grupos: Grupo controle - pericardiotomia. Grupo Talco - colocação de talco sobre o epicárdio. Grupo PVAl - colocada membrana de PVAl circundando o coração. Grupo PVAl + Talco - colocado talco sobre o epicárdio e a membrana de PVAl circundando o coração. Após oito semanas foi realizada análise macroscópica e histológica dos corações. Avaliação estatística foi realizada com análise de variância (ANOVA) e teste de Dunnett com significância p<0,05. Resultados: A membrana de PVAl não apresentou citotoxicidade, sua capacidade de absorção de água foi de 42,4 ± 0,89% e mostrou valor médio de 0,00422± 0,00256% de cálcio da massa total do material analisado. Na análise macroscópica observou-se maior aderência no grupo Talco. Na análise histológica o grupo PVAl + Talco apresentou maior espessura epicárdica. Os grupos T e PVAl + Talco apresentaram maior número de células inflamatórias. Conclusão: A membrana não é citotóxica, apresentou boa capacidade de hidratação, a absorção de cálcio foi desprezível, não induziu formação de aderências pericárdicas, não provocou aumento da espessura epicárdica e não induziu aumento de migração de células de resposta inflamatória para o epicárdio, mostrando-se interessante para a aplicação desejada.
Abstract: Background: Cardiac surgery reoperations represent around 20% of all surgical procedures. The main incision is sternotomy and after the first operation there are adherences joining the heart, sternum and neighboring structures. Cardiac chambers and great vessels lesions caused by sternal saw increase morbidity and mortality as well as perioperatory bleeding. Several authors had tried pericardial replacement with biological or synthetic materials in order to decrease risks at reoperations, however with no significant results on long term. Polyvinyl alcohol (PVAl) is a well-known hydrogel, with good biocompatibility and favorable properties as a pericardium replacement. Objective: Describe the biological PVAl behavior as a pericardial replacement. Methodology: PVAl samples were reticulated by radiation. Cytotoxicity direct and indirect tests with VERO cells were performed. We tested absorption water capability and in vivo calcification. Wistar rats were divided in four groups: Control - pericardium abrasion; Talc - talc insertion surrounding the heart; PVAl membrane - PVAl surrounding the heart; PVAl + talc - talc and PVAl membrane insertion surrounding the heart. All animals were kept for 8 weeks and euthanized for study. Macroscopic and microscopic analyses were performed. Statistical analyses were performed with ANOVA and Dunnett post test. Results: The PVAl membrane showed no cytotoxicity. The water absorption capability was 42,4 ± 0,89%. The calcification test showed only 0.00422± 0.00256% of calcium in the total mass of analyzed material. Macroscopic analysis showed higher adherences in the talc group. Histological analysis showed higher epicardium thickness in the PVAl + talc group, higher inflammatory cells in the talcum and PVAl + talc groups. Conclusion: The PVAl membrane hasn't cytotoxicity. It has good water absorption capability and calcification was insubstantial. The membrane showed neither adherences formation nor inflammatory response ...Note: The complete abstract is available with the full electronic digital thesis or dissertations.
Doutorado
Pesquisa Experimental
Doutor em Cirurgia
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Abreu, Mariane Martim Sobrosa Passos de. "Preparação e caracterização de compósitos híbridos de talco e resina epóxi-anidrido." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/97/97134/tde-24032015-152637/.
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Neste trabalho foi realizado o estudo térmico, cinético e dielétrico durante a cura de um compósito constituído de uma matriz de resina epóxi-anidrido e de talco como carga modificadora das características dielétricas e mecânicas da matriz polimérica. Foram analisadas também as propriedades dinâmicas mecânicas e morfológicas dos compósitos completamente curados. O interesse na investigação das características térmicas, cinéticas e dielétricas visou encontrar correlação entre essas características e as propriedades dinâmicas mecânicas finais dos compósitos. Foram estudados os compósitos com diferentes concentrações de carga, variando de 0 a 10% m/m, utilizando as técnicas de calorimetria exploratória diferencial (DSC), de análise dielétrica (DEA), análise termomecânica dinâmica (DMTA) e análise por microscopia eletrônica de varredura (MEV). Os resultados da análise DSC foram analisados por método isotérmico (modelo de Sourour-Kamal modificado) e por método dinâmico (modelo isoconversional). Os resultados da análise da cura dos compósitos mostraram que a concentração da carga retarda o processo de cura, conforme observado pela análise dielétrica; a temperatura de transição vítrea do compósito curado apresentou valores mínimos nas concentrações de 7 e 10%, enquanto que a análise térmica dinâmica previu que a energia de ativação aumenta com o grau de conversão. Os resultados da análise termomecânica dinâmica mostraram o aumento no módulo de armazenamento a 25ºC de 2,1 GPa (0% talco) a 3,3 GPa (10% talco), indicando haver o efeito reforçador do talco sobre a matriz polimérica. As micrografias dos compósitos foram um excelente recurso para estudar suas morfologias e se correlacionam com os resultados cinéticos e mecânicos.In this work we performed the thermal, kinetics, dielectrical and morphological studies on the curing of a hybrid composite material composed of epoxy-anhydride matrix and talc as modifier agent of the dielectrical and mechanical properties of the polymer matrix. It also was studied the dynamic mechanical properties of the full-cured composite materials. This investigation aimed to correlate the thermal, kinetics, and dielectrical characteristics of the curing material with their final mechanical properties. Composite materials with different talc concentrations were studied in the range from 0% up to 10% w/w, employing the Differential Scanning Calorimetry (DSC), the Dielectric Analysis (DEA), Dynamic Mechanical Thermal Analysis (DMTA) and Microscopy Electron Scanning (SEM) techniques. The DSC experimental results were analyzed through the isothermal method (Modified Sourour-Kamal model) and the dynamic method (Isoconversional model). The cure analysis results of the composite specimens showed the talc acting as a cure retardant as observed from DEA results; the glass transition temperature of the full-cured composite materials showed minimum values at talc concentrations of 7 and 10%, while the dynamic thermal analysis predicted the activation energy is increasing with the conversion degree. The DMTA results exhibited the storage modulus at 25ºC increases from 2.1 GPa for the matrix without talc up to 3.3 GPa at 10% talc concentration composite, thus indicating the reinforcement role of the talc on the polymer matrix. The composites micrographs were an excellent resource for study their morphologies and for correlation of kinetics and mechanical results.
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Lebre, Cédric. "Elaboration et caractérisation de talcs synthétiques pour l'amélioration des propriétés physiques des matériaux composites industriels." Toulouse 3, 2007. http://thesesups.ups-tlse.fr/223/.
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La synthèse hydrothermale argileuse (150°C-550°C) est un moyen technique d'obtention de phases minérales de grande pureté à chimie contrôlée. Les pressions dans les réacteurs, le prix des produits interdisent la fabrication à l'échelle industrielle. Les procédés hydrothermaux développés dans cette étude ont montré la possibilité d'obtention de phases minérales argileuses de type talc en grande quantité (kg) à chimie parfaitement contrôlée, ayant des tailles granulométriques nanométriques à sub-microniques, tailles de particules sans concurrence avec celles des talcs naturels qui sont au minimum micronique. Le magnésium octaédrique a été substitué par du nickel et cobalt. Les produits obtenus sont colorés ainsi que les solutions solides entre les pôles Mg-Ni, Mg-Co et Ni-Co. Les paramètres température, pression, et temps de synthèse permettent de contrôler la taille des particules et la minéralogieThe hydrothermal synthesis of clays (150°C - 550°C) is a technical way to obtain mineral phases of high purity with controlled chemistry. Pressures in reactors and product costs forbid fabrication at industrial scale. Hydrothermal processes developed in this study have shown possibility to obtain mineral phases of clay, with a granulometric size from nanometric to submicronic. These sizes are unrivalled to natural talc's one which is at least micronic. Octahedral magnesium has been substitute by nickel and cobalt, which give coloration of products as well as solid solution Mg-Ni, Mg-Co and Ni-Co. Pressure, temperature, and synthesis duration are parameters which control size of particle and mineralogy
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Lobato, Emilio Marcus de Castro. "Determination of Surface Free Energies and Aspect Ratio of Talc." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35743.
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Microcalorimetric measurements and contact angle measurements were conducted to assess the surface chemistry of the mineral talc. The contact angles were performed on both flat and powdered samples and the results were used to determine the surface free energy components and parameters (SFEC) using the acid-base theory for solids, according to the van Oss-Chaudhury-Good approach. It was found that the surface hydrophobicity of talc increases with decreasing particle size up to a limit after which hydrophilicity (polarity) increases. The increase in hydrophobicity was attributed to the increase of the delamination of the lamellar talc particles. Delamination is a comminution mechanism that preferentially exposes talc's hydrophobic basal planes, while fracture is another mechanism that breaks the lamellae, rupturing covalent bonds thus exposing more hydrophilic edge surfaces. The decrease in hydrophobicity, beyond a given particle size, could be related to the prevail of fracture over delamination during grinding which generated more hydrophilic edge surfaces.
The flow microcalorymetry combined with thin layer wicking allowed the separate estimation of the SFEC at the basal plane and edge surfaces of talc. The results suggested that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic, which are in agreement with the crystal structure of the mineral.
The combination of two particle size distribution techniques, which are based on different physical principles, permitted the quantitative determination of the aspect ratio of highly anisometric particles, such as talc. The same trend obtained using flow microcalorimetry was observed for the evolution of the aspect ratio as a function of particle fineness, i.e. the fracture prevails over delamination after achieving a maximum aspect ratio value of about 35. The agreement between two distinct methods was considered rather encouraging.
Master of Science
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ARSEGUEL, DIDIER. "Interactions talc-enzyme : incidence sur les proprietes et les applications." Toulouse 3, 1992. http://www.theses.fr/1992TOU30281.
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Dans une premiere phase bibliographique, afin de mettre en evidence les consequences d'une immobilisation sur la structure et l'activite catalytique d'un biocatalyseur, nous avons decrit et correle les differents parametres impliques: proprietes de surface du talc, les forces responsables de la structuration proteique et les phenomenes de catalyse enzymatique en phase heterogene. Nous avons etabli un bilan des differentes techniques d'immobilisation envisageables. Dans une deuxieme phase, des donnees sur les interactions talc-enzyme ont ete obtenues par immobilisation de differentes categories d'enzymes: lipases, proteases, peroxydase de raifort native ou modifiee chimiquement sur differentes substances talqueuses: talc chlorite, talc chimiquement et thermiquement modifie. Nous avons developpe une technique de modification chimique d'enzyme et de visualisation (infra-rouge a transformee de fourier). Les proprietes catalytiques des enzymes natives et immobilisees ont ete determinees. Une ebauche de relation structure-activite a ete realisee par modelisation de l'adsorption des enzymes sur le talc. Dans une troisieme phase, une application a ete developpee. Elle concerne le couplage du talc a un systeme enzymatique de depollution d'eaux phenolees: peroxydase de raifort plus oxydant. Apres etude des differentes interactions des constituants du milieu: talc, enzyme, phenol, produits d'oxydation, nous avons optimise le systeme existant. Le nouveau procede de depollution a base de talc permet d'atteindre un taux de phenol residuel plus faible et une elimination facile et rapide des produits d'oxydation (polyphenols)
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Power, Matthew R. "Models for the genesis of industrial minerals in mafic and ultramafic rocks." Thesis, University of Exeter, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245925.
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Schmitt, Philippe. "Application de la chromatographie gazeuse inverse à la caractérisation de surface de talcs." Mulhouse, 1986. http://www.theses.fr/1986MULH0023.
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Lebre, Cédric Martin François. "Elaboration et caractérisation de talcs synthétiques pour l'amélioration des propriétés physiques des matériaux composites industriels." Toulouse (Université Paul Sabatier, Toulouse 3), 2008. http://thesesups.ups-tlse.fr/223.
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FALCÃO, Mariana Cavalcanti. "A sustentabilidade do destino turístico de Fernando de Noronha: uma análise a partir da abordagem do ciclo de vida de áreas turísticas e das dimensões da sustentabilidade." Universidade Federal de Pernambuco, 2010. https://repositorio.ufpe.br/handle/123456789/1197.
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Previous issue date: 2010Universidade Federal de Pernambuco
A finalidade dessa investigação foi analisar a sustentabilidade do destino turístico de Fernando de Noronha com base na abordagem do ciclo de vida dos destinos turísticos e dimensões da sustentabilidade. O arcabouço teórico consultado foi guiado pela discussão acerca do turismo e seus aportes conceituais, as limitações e potencialidades do modelo teórico Tourism Areas Life Cycle (TALC) além do debate teórica sobre a sustentabilidade e sua dimensões e a análise da sustentabilidade de uma localidade o que serviu de base para proposta de adaptação do TALC às dimensões da sustentabilidade. O estudo se caracteriza como um estudo de caso qualitativo tendo sido realizado no Arquipélago de Fernando de Noronha atual distrito administrativo do Estado de Pernambuco, região Nordeste do Brasil. Para coleta de dados foram realizadas entrevistas semi-estruturadas, análise documental e observação direta. Os principais resultados da pesquisa são: 1) adaptação do TALC às dimensões da sustentabilidade se faz possível uma vez identificada a lacuna existente no modelo teórico sobre a impossibilidade de traçar ações em direção ao desenvolvimento sustentável; 2) Em apenas 44 anos Fernando de Noronha atingiu quatro dos seis estágios do ciclo de vida possíveis e presencia no momento atual um momento de sobreposição dos indicadores das fases de desenvolvimento e consolidação; 3) O arcabouço teórico consultado possibilitou o estabelecimento de 14 indicadores e 43 critérios de análise para avaliação das dimensões da sustentabilidade; e 4) a dimensão política-institucional apresentou o melhor resultado comparado às outras dimensões analisadas. Por fim, a investigação aponta para um retrato positivo acerca da sustentabilidade de Fernando de Noronha, embora tenha que ser considerado os aspectos limitantes do desenvolvimento da atividade turística, conforme exposto nos resultados das seis dimensões da sustentabilidade avaliadas neste trabalho
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Garcia, Vidal Claudio Andres. "Molecular weight effects in guar gum adsorption and depression of talc." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44116.
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The effect of the molecular weight of guar gum on adsorption, talc depression, and stability of talc suspensions was studied. Four guar gum samples of different molecular weights in the range from 0.162 MDa to 1.4 MDa were used. It was also found that the intrinsic viscosities of the guar gum samples were independent of the type of background solution (NaCl, KCl, distilled water).
The adsorption density of the tested guar gum samples on talc was measured from the same background solutions at pH 9. The floatability of fine talc particles as well as their stability towards aggregation in the presence of guar gum were simultaneously determined so a direct relationship between talc depression and talc flocculation/dispersion by guar gum could be established. It was found that the effect of the molecular weight of guar gum on the adsorption density was negligible. No effect of the background electrolyte on guar gum adsorption was observed. All four guar gum samples were found to be equally strong depressants of talc flotation without any clear relationship with their molecular weights. It was determined that an adsorption density equal to about 20% of the complete surface coverage was sufficient to completely depress talc floatability. All guar gum samples also exhibited strong flocculating capabilities towards the talc particles at lower polymer dosages. As determined from turbidity data, higher molecular weight guar gum samples were more powerful flocculants than lower molecular samples. Most importantly, the strongest depression of talc flotation and the most pronounced flocculation of talc were found to occur at the same dosage. Higher doses of the polymers kept the talc particles completely depressed while simultaneously causing gradual steric redispersion of the mineral. The dispersing capabilities of the polymers were a function of the molecular weight, with the lower molecular weight samples bringing about stronger dispersion than higher molecular weight samples.
It was concluded that a high molecular weight guar gum would be the best depressant, since such a polymer would strongly depress the flotation of talc while minimizing talc dispersion and subsequent mechanical entrainment in the flotation concentrate.
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Corona, Juan Carlos. "An experimental investigation of the reaction glaucophane + 2 quartz = 2 albite + talc /." Diss., Online access via UMI:, 2005.
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Amini, Shahsavarani Arjang. "Improvement of the properties of novel bioplastics through reactive compatibilization." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/14566.
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Bioplastics are emerging as most promising materials to replace oil based thermoplastics particularly in packaging. Bioplastics can mitigate and address concerns about the negative role of plastics in the environment creating pollution and depleting resources hence bioplastics can enable an innovative approach toward addressing these issues. However, manufacturing of bioplastic is still costly and their mechanical and thermal properties require extensive development. Therefore there has been substantial interest to improve processing and properties of bioplastics to diminish the environmental impacts caused by continuous use of synthetic polymers of petroleum origin. In this research, Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV and Polybutylene succinate (PBS) composites and blends were developed to improve the properties of PHBV as the matrix polymer and hence produce a novel formulation for product development. Three approaches were studied in this work: The effect of talcum powder as a nucleating agent and reinforcing filler. The effect of oligomer chain extenders on miscibility, crystallinity, thermal and thermomechanical, mechanical and morphological properties of PHBV/PBS blends. The effect of acrylic core-shell impact modifier on crystallinity, thermal and thermomechanical, mechanical and morphological properties of PHBV were also evaluated. All the above scientific approaches have been studied. It was noticed that talc can change the sluggish crystallinity of PHBV. Talc enhances nucleation of PHBV in the composites which leads to a faster crystallization rate. The heat distortion temperature, crystallinity and the modulus of PHBV/talc composite were also increased. In the presence of the chain extender (CE) the miscibility conditions of PHBV/PBS blends were changed. The results were supported by calculation of the activation energies. The elongation at break and tensile strength of PHBV/PBS/Chain extender blends increased indicating miscibility change. The possible reaction mechanism between PHBV, PBS and CE are proposed and the results supported by using FTIR. Immiscibility results of the PHBV/PBS blends are supported by SEM images. Addition of the impact modifier to PHBV reduced the crystallization rate and prolonged crystallization time. It has been found that the shell of impact modifier (PMMA) is partially miscible with PHBV. The absorbed impact energy is improved by the impact modifier but the improvement was not as satisfactory as results noted for PLA. The SEM images showed the average fine dispersion of different sized particles inside the matrix.
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Orellana, Ronald Vargas. "Avaliação das propriedades mecânicas de um silicone de cura acética com adição de silicato de magnésio." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/23/23144/tde-02012008-122236/.
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Os silicones requerem várias caraterísticas e requisitos para seu uso na confecção de próteses faciais, principalmente, referente a textura da pele; para alcançar essa meta devem ser adicionados outros materiais. O objetivo deste trabalho foi avaliar as propriedades mecânicas de um silicone nacional RTV. de cura acética, disponível no mercado, adicionando silicato de magnésio (talco). O material foi estudado em seu estado original e com acréscimo de 10% e 20% de silicato de magnésio. Foi submetido a testes de alongamento de ruptura, resistência à tração ou tensão de ruptura e de resistência ao rasgamento. Após a avaliação individual dos corpos de prova, obteve-se uma média total de cada grupo e submeteu-se a estudo comparativo frente aos resultados obtidos por meio de análise de variância (ANOVA) e teste de Tukey. O silicone em estado original mostrou-se mais resistente ao alongamento. O silicone com adição de 10 % de silicato de magnésio modificou suas propriedades mecânicas e obteve maior resistencia à tração. O silicone com adição de 20 % de silicato magnésio obteve maior resistência ao rasgamento. O silicone em que foi adicionado 10 % de silicato de magnésio de maneira geral obteve os valores mais significativos nas três propriedades testadas, o que indica que adicionando mais de 10 % diminui as propriedades mecânicas gradualmente, tornando-se inversamente proporcionais.The silicones request many characteristics and requirements for the use in the making of facial prostheses. To reach that objective other materials should be added. The aim of this work was to evaluate the mechanical properties of a national acetic cure silicone RTV, available in the market, adding silicate of magnesium (talc). The material was studied in your natural state and with increment of 10% and 20% of silicate of magnesium. It was submitted to tests of elongation and break, tensile strength and tear strength. After the individual evaluation of the specimens, it was obtained measured total of the each group and submitted to study comparative front to the results obtained through variance analysis (ANOVA) and Tukey test. The silicone in been original it showed to be more resistant to the elongation. The silicone with addition of 10% of silicate of magnesium modified your mechanical properties and obtained larger tear resistance. The silicone with addition of 20% of silicate magnesium obtained larger resistance to the tear strength. The silicone in witch it added 10% of silicate of magnesium in general obtained the more significant values in the three tested properties; that means that the increment of more than 10% lesses the properties gradually, becoming inversely proportional.
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Bailey, Lynn Marie. "An unusual diamond-bearing talc schist from the Dachine area of French Guiana." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ37937.pdf.
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Charnay, Clarence. "Formulation de suspensions concentrées de talc : physico-chimie des interfaces et analyses rhéologiques." Montpellier 2, 1999. http://www.theses.fr/1999MON20186.
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La mise en suspension de particules de talc implique la formation d'une interface solide-liquide, dont il est necessaire de controler les proprietes rheologiques pour obtenir un systeme qui presente le meilleur compromis entre les proprietes d'ecoulement et de stabilite vis a vis de la sedimentation. La repartition des surfaces hydrophile et hydrophobe est un parametre important, bien que rarement caracterise, pour decrire l'interface talc-solution aqueuse. Nous nous sommes proposes d'etudier le rapport de ces surfaces en utilisant les techniques d'adsorption de molecules sondes, cation organique et tensioactifs cationiques et anioniques. A partir de considerations geometriques qui reposent sur l'analyse des resultats relatifs a l'adsorption, et sur la forme des agregats adsorbes, nous avons developpe une methode originale permettant la mesure des aires des surfaces hydrophiles et hydrophobes de nos echantillons. Une etude rheologique des suspensions aqueuses de talc-chlorite en regime permanent et dynamique est ensuite proposee pour optimiser le choix des agents dispersants. Les caracteristiques physico-chimiques de la surface des particules de talc sont a l'origine de leur agregation. Aux faibles cisaillements, les suspensions presentent un comportement de type pseudo-plastique a contrainte seuil caracteristique d'un amas infini. Les proprietes rheologiques des suspensions montrent que l'energie d'adhesion des particules est faible ce qui confirme l'agregation par des interactions hydrophobes. Afin de disperser les particules de talc et augmenter la fraction massique des suspensions, l'utilisation de polymeres de type polyacrylate est une voie privilegiee. La dispersion des particules se traduit alors par une diminution de la viscosite et par la disparition des proprietes thixotropes et viscoelastiques des suspensions. La derniere partie de cette etude concerne la recherche d'une formulation optimale qui vise a limiter la sedimentation des particules tout en conservant une bonne coulabilite sous cisaillement. L'emploi de polymeres associatifs capables de former un gel physique dans la suspension au repos permet de pieger les particules de talc et de bloquer la sedimentation.
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Guillon, Didier. "Etude de la réticulation d'un mastic polyester de réparation de carrosserie : amélioration de la ponçabilité du talc et accroisement de la résistance au vieillissement du mastic." Toulouse, INPT, 2005. http://www.theses.fr/2005INPTA001.
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La formulation d’un mastic de carrosserie est complexe et présente un taux élevé de talc indispensable à une bonne ponçabilité du produit fini. Malheureusement, peu de talcs sont vraiment ponçables et la méconnaissance des paramètres influents nécessite une évaluation de la charge lamellaire. Le durcissement du mastic chargé est comparé à celui du polyester non chargé. L’effet auto-catalytique de la réaction est observé dans les deux types de mastic. Des techniques d’analyse IR de ce mastic ou de sa poudre poncée sont établies ou améliorées pour suivre sa réticulation et quantifier ses insaturations résiduelles. L’influence de quatre talcs et d’une calcite est étudiée : une corrélation entre la vitesse de réaction inférieure, une bonne ponçabilité et une faible dureté est démontrée. L’observation de la cinétique de réticulation plus lente des charges ponçables est mise à profit pour améliorer la ponçabilité du talc. Parmi cinq solutions d’amélioration évaluées, trois sont efficaces dans les conditions testées diminution du taux de peroxyde, ajout de retardateur et flottation du talc) et deux inefficaces (ajout d’inhibiteur et de résine souple). La validation par le marché de la seconde option efficace est en cours, les deux autres étant validées. 11 000 tonnes par an de talc pourraient être valorisées à un prix de 230 euros/t et permettrait de réduite un stock actuellement inutilisé de plus de 100 000t. Cette étude démontre aussi l’influence de certains talcs sur le vieillissement du mastic et, en particulier, un phénomène d’apparition de « mousse blanche » jusque là inexpliqué et maintenant attribué à une polymérisation intempestive du styrène. Une forte remontée de liquide est constatée dans plusieurs formules et l’analyse IR démontre la présence très majoritaire de résine et de styrène. Une nouvelle série de vieillissement est en cours pour évaluer la résistance à la température de ces masticsA bodyfiller formulation is complicated and shows a high talc level absolutely necessary to provide a good sandability of the putty. Unfortunately, only some talcs are sandable and parameters influencing this property are unknown. A former talc evaluation is therefore essential. The curing reaction of the filled putty is compared to the unfilled polyester’s one. A gel effect in the reaction is observed in both products. IR analysis protocols suitable for the putty or for its sanded powder are created or improved to follow up the curing reaction and to quantify its residual double bonds. The influence of some talcs and one calcite is studied : a correlation between a lower speed curing, a good sandability and a low hardness is shown. The observation of the lower curing speed of sandable fillers is used to improve the sandability of talcs. Among five options to improve sandability, three are efficient (reduction of the peroxide level, retarding agent addition and talc floatation) and two others are not (addition of an inhibitor or a flexible resin). Market validation of the second efficient option is in progress while two others are already validated. 11 000 tons per year of talc could be valorised at a selling price about 230euros/t and would help to reduce a 100 000 tons stock of unused talc. This study shows also the influence of some talcs on the thermal ageing of the putty, as well as a “white foam” appearance phenomenon unexplained until now and found to be an undesired styrene polymerisation. A deep liquid/filler separation is observed with some of the evaluated formulations and IR analysis shows the liquid part is mainly based on styrene and polyester resin. A new set of thermal ageing trials is in progress to evaluate the thermal resistance of these putties
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Terra, Ricardo Mingarini. "Análise de resultados clínicos e radiológicos de dois métodos de pleurodese com talco em pacientes com derrame pleural maligno recidivante." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5156/tde-25032009-092144/.
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Introdução: A pleurodese com talco é o método mais popular para controle sintomático do derrame pleural maligno recidivante. A administração intrapleural do talco pode ser por videotoracoscopia ou dreno de tórax e qual o melhor método é uma questão controversa. Ainda que a expansão pulmonar seja um dos principais critérios de sucesso do procedimento, suas características pós-pleurodese ainda são pouco estudadas. Objetivo: Avaliar a expansão pulmonar após dois diferentes métodos de pleurodese com talco (dreno de tórax ou videotoracoscopia) em pacientes com derrame pleural maligno recidivante, considerando a evolução radiológica, diferença entre os métodos e correlação com desfecho clínico. O objetivo secundário foi comparar ambos os métodos quanto a: efetividade clínica, segurança, qualidade de vida e sobrevivência. Método: Estudo prospectivo randomizado que incluiu 60 pacientes (45 Mulheres, 15 Homens, idade média: 55,2 anos) com derrame pleural maligno recidivante entre janeiro de 2005 e janeiro de 2008. Os pacientes foram alocados em dois grupos: videotoracoscopia com insuflação de talco (VT) ou instilação de talco por dreno de tórax (DT). A expansão pulmonar imediata e a evolução da expansão pulmonar foram avaliadas através de tomografias de tórax obtidas nos primeiros 7 dias, 1, 3 e 6 meses após a pleurodese, as quais foram analisadas por dois observadores independentes. Efetividade clínica (considerada como ausência de necessidade de novos procedimentos pleurais durante o seguimento), complicações, tempo de drenagem e de internação hospitalar e qualidade de vida (questionários gerais e específicos) foram também analisados. A análise estatística foi realizada através dos testes de Qui-quadrado e Fisher para as variáveis categóricas e Mann-Whitney para variáveis contínuas não paramétricas. A sobrevivência foi analisada através do método de Kaplan- Meier e o teste de log-Rank para foi usado para identificar fatores que interferissem na sobrevida. Os resultados dos questionários de qualidade de vida foram avaliados através de ANOVA de duplo-fator. Resultados: Não houve diferença significativa entre os grupos nas variáveis clínicas préoperatórias. A expansão imediata total (>90%) foi observada em 27 (45%) pacientes e foi mais freqüente no grupo VT (60 vs. 30%, p=0.027). Durante o seguimento, 71% dos pacientes estudados tiveram melhora ou ao menos mantiveram a expansão pulmonar observada na 1ª tomografia, fato que ocorreu de forma semelhante entre os grupos (p=0,58). Novos procedimentos pleurais foram necessários em 9(15%) pacientes (5 recidivas no grupo VT e 4 no grupo DT, p=0.999). Não foram encontradas diferenças entre os grupos quanto a: complicações, tempo e de internação. A análise dos questionários de qualidade de vida revelou resultados semelhantes para ambos os grupos. A expansão pulmonar imediata não se correlacionou com recidiva radiológica, recidiva clínica ou complicações (p= 0.60, 0.15 e 0.20, respectivamente). A sobrevida após ambos os procedimentos foi semelhante, porém a ocorrência de recidivas foi um fator relacionado a sobrevida mais curta (p=0,02). Conclusão: Expansão pulmonar imediata parcial foi freqüente, particularmente no grupo DT. Contudo, manutenção do quadro radiológico e até melhora radiológica ocorreram na maioria dos casos. Não foi encontrada correlação entre expansão pulmonar imediata e desfecho clínico neste estudo.Introduction: Talc pleurodesis is the most popular method to control recurrent malignant pleural effusion symptoms. Two methods may be used to deliver talc into the pleural space: videothoracoscopy or talc slurry through a chest tube ; which is the best method is still controversial. Although lung expansion is the most accepted pleurodesis outcome variable, its features are poorly studied. Objective: To analyze and compare radiological lung expansion after talc pleurodesis performed either by videothoracoscopy or chest tube and correlate it with clinical outcome. Secondary endpoints evaluated were: clinical efficacy, safety, quality of life and survival. Methods: Prospective randomized study that included 60 patients (45 Female, 15 Male, mean age: 55,2 years) with recurrent malignant pleural effusion, between January, 2005 and January, 2008. They were enrolled into two groups: videothoracoscopic talc poudrage (VT) and talc slurry through a chest tube (TS). Lung expansion was evaluated through chest CT scans obtained in the first 7 days and 1, 3 and 6 months after pleurodesis. All examinations were revised by two independent observers. Clinical efficacy (considered as lack of new procedures during follow up), complications, drainage duration, hospital stay and quality of life (general and specific questionnaires) were also analyzed. Categorical variables were compared with the Chi-Square test or Fisher´s exact test for small samples. Mann-Whitney test was used to compare continuous non parametric variables. Survival curves were calculated according to the Kaplan-Meier method and Log-rank test was used to identify factors that could interfere with survival. Double factor ANOVA was used to compare quality of life questionnaires results. Results: No significant difference in pre-procedure clinical variables was observed between groups. Postoperative lung expansion was total (>90%) in 27 (45%) patients and was more frequent in VT group (60% vs. 30%, p=0.027). During follow-up 71% of the patients showed unaltered or improved lung expansion and lung expansion evolution was similar in both groups (p=0.58). Nine (15%) patients needed new pleural procedures (5 recurrences in VT group and 4 in DT group, p=0.999). No statistical difference was found between groups regarding complications, drainage time and hospital stay. Quality of life questionnaires were evaluated but no difference between study arms was observed. There was no correlation between initial lung expansion and clinical recurrence, radiological recurrence or complications (p = 0.60, 0.15 and 0.20, respectively). No difference in survival between study arms was observed, but a shorter survival was observed in patients that developed clinical recurrence (p=0.02). Conclusion: Immediate partial lung expansion was a frequent finding and was more frequent in TS group. However, maintenance of the radiological image and even radiological improvement occurred in most cases. No correlation between immediate lung expansion and clinical outcome was found in this study
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Poirier, Mathilde. "Fonctionnalisation et cristallochimie de talcs synthétiques submicroniques." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30237.
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Le talc synthétique est un matériau à fort intérêt industriel du fait de sa taille submicronique, de sa large surface spécifique (> 300 m²/g), et de ses propriétés hydrophiles, qui lui offrent un large éventail d'applications dans des secteurs industriels variés (polymères, cosmétiques, papiers, peintures, médecine, ...). Dans cette thèse, les potentialités d'adsorption du matériau ont été testées vis-à-vis de différents composés organiques et/ou inorganiques à propriétés physico-chimiques souhaitées (composés colorés et/ou fluorescents, nanoparticules métalliques), afin d'élaborer de nouvelles charges minérales fonctionnelles et innovantes (e.g. talcs synthétiques fluorescents). Les résultats montrent que le matériau présente une forte capacité à adsorber les composés testés, qui est bien supérieure à celle de son homologue naturel de taille pluri-micronique. La recherche des mécanismes d'adsorption se produisant à l'interface "minéral - adsorbat" a par la suite conduit à étudier de plus près la cristallochimie du talc synthétique non fonctionnalisé, en utilisant plusieurs méthodes de caractérisation comme la Diffraction des Rayons (DRX), la spectroscopie de Résonance Magnétique Nucléaire (RMN), ou bien encore la spectroscopie d'Absorption des Rayons X (XAS). Outre le fait que de grandes avancées ont été faites sur la caractérisation cristallochimique des particules, les résultats majeurs montrent que les minéraux synthétiques ne doivent pas être regardés de la même manière que les minéraux naturels, du fait de leur taille nanométrique qui engendre obligatoirement une perturbation des signaux observés. Les résultats montrent notamment que les méthodes de caractérisation qui sont classiquement utilisées en DRX pour calculer les distances inter-réticulaires ne doivent pas être appliquées sur les nanomatériaux du fait du faible empilement des particules suivant l'axe cristallographique c*. Il faut pour cela faire appel à des méthodes de simulation numériques pour déterminer les valeurs des distances inter-réticulaires réelles. De la même manière, les résultats montrent que les signaux RMN sont également impactés par la taille nanométrique des particules du fait d'une différenciation des signaux provenant du cœur des particules, de ceux provenant des surfaces externes des particules. Ces résultats ont été mis en évidence en combinant une approche expérimentale par RMN à une approche théorique par DFT (Density Functional Theory).[;;;]Synthetic talc is a material of great industrial interest because of its submicronic size, its large specific surface area (> 300 m²/g), and its hydrophilic properties, offering a wide range of applications in the fields of polymers, cosmetics, papers, paints, or medecine. In this thesis, the adsorption capacity of the material was tested towards different organic and/or inorganic compounds of desired physicochemical properties (coloured and/or fluorescent compounds, metallic nanoparticles), to elaborate new mineral fillers with functional and innovative characteristics (e.g. fluorescent synthetic talc particles). The results show that synthetic talc particles possess a much higher adsorption capacity towards organic and inorganic compounds, compared to natural plurimicron-sized talc particles. Research on the adsorption mechanisms occuring at the " mineral - adsorbate " interface was followed by the study of the crystal-chemistry of the material, using a combination of several characterization techniques such as X-Ray Diffraction (XRD), Nuclear Magnetic Resonance spectroscopy (NMR), or X-Ray Absorption spectroscopy (XAS). Beyond the fact that a great progress was made on the overall crystal-chemistry of the particles, the main results show that " synthetic minerals " should not be considered in the same way as " natural minerals " due to their nanometric size which necessarily disturbed the observed signals. As an example, the methods conventionally used in XRD to determine the interplanar spacings should not be applied on nanomaterials because of their very low particle stacking and numerical simulations shall be used instead. Similarly, our study shows that NMR signals are also impacted by the nanometric size of the particles because of a spectral differentiation of the signals coming from the bulk of the particles versus the ones coming from the external surfaces of the particles. These results were highlighted by combining an experimental NMR approach and a theoretical DFT (Density Functional Theory). Those external surfaces, which contain crystalline defects, are probably responsible for the high adsorption capacity of the material, and may explain some of the crystallogenesis processes that have been observed by XAS spectroscopy. To conclude, nano-sized lamellar synthetic materials represent a great tool to investigate the surface crystal-chemistry of natural minerals, as they revealed new contributions which were previously undetectable in larger-sized minerals
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Etcheverry, Bernard. "Adhérence, mécanique et tribologie des revêtements composites NiP - Talc multifonctionnels à empreinte écologique réduite." Phd thesis, Toulouse, INPT, 2006. http://oatao.univ-toulouse.fr/7549/1/etcheverry1.pdf.
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Cette étude porte sur la caractérisation des propriétés de revêtements à matrice Ni-P chargés en particules de talc à empreinte écologique réduite. Les réponses locales des revêtements bruts ou traités thermiquement, soumis à des sollicitations thermomécaniques statiques et dynamiques, ont été obtenues par nano- et -microdureté, microtraction, nanorayage et essais tribologiques. La dureté et la rigidité augmentent après un traitement thermique de cristallisation à 420°C (précipitation de Ni3P). Un traitement à plus haute température (T>600°C) diminue par survieillissement ces caractéristiques. Le traitement à 420°C améliore l'adhérence des revêtements et leur cohésion quelle que soit la teneur en talc. Des essais tribologiques ont été réalisés à température ambiante et à 600°C. A température ambiante, les revêtements NiP-talc traités ont un très bon comportement à l'usure. A 600°C, les mécanismes de dégradation sont nettement intensifiés et affectent les échantillons et les frotteurs.
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Parseval, Philippe de. "Etude minéralogique et géochimique du gisement de talc et chlorite de Trimouns (Pyrénées, France)." Toulouse 3, 1992. http://www.theses.fr/1992TOU30184.
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Le gisement de talc et chlorite de trimouns s'est forme par l'alteration hydrothermale de roches variees. Les minerais a talc pur proviennent de la transformation de dolomies et ceux a chlorite magnesienne predominante sont issus de roches silico-alumineuses (micaschistes et pegmatites). L'etude mineralogique definit la nature et composition des mineraux dans les differentes zones d'alteration, notamment les mineraux accessoires neoformes dans les minerais (fluorapatite, sphene, rutile. . . ). L'etude geochimique des diverses lignees d'alteration precise le comportement des elements majeurs, traces et des terres rares. On montre que les terres rares legeres passent en solution lors de l'alteration et precipitent sous forme de mineraux divers (allanite, bastnaesite,. . . ) dans les dolomies au toit du gisement. Les mecanismes de la transformation des micas en chlorite sont etudies par microscopie electronique en transmission haute resolution dans le cas de l'alteration de pegmatites en chloritites. Le phenomene de dissolution-recristallisation caracterise la transformation muscovite-chlorite et deux mecanismes de transformation a l'etat solide ainsi que des phenomenes de dissolution-recristallisation sont mis en jeu dans le cas de la transformation de phlogopite en chlorite. L'analyse par spectrometrie mossbauer de minerais chloriteux et talqueux montre que fe#3#+ occupe les sites tetraedriques des chlorites et du talc et que fe#2#+ est dans les sites octaedriques des chlorites. La distribution de ce fe#2#+ est differente en fonction de l'origine (pegmatitique ou micaschisteuse) du minerai chloriteux. L'etude des inclusions fluides precise les conditions de formation (320c, 2. 5 kbar) et definit deux types de fluides a h#2o (co#2) de salinite elevee (20 a plus de 30% de sels: cacl#2, nacl, mgcl#2,. . . ). Ces resultats permettent de modeliser la transformation de dolomite en talc et de proposer un schema d'ensemble des modalites de formation du gisement
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Berthaud, Daniel. "Analyse fonctionnelle d'une usine de traitement de talc et intégration d'un outil de supervision." Nancy 1, 1992. http://www.theses.fr/1992NAN10157.
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L'automatisation et l'informatisation des systèmes de conduite de processus industriels entrainent la centralisation des organes d'affichage et de commande sur des consoles graphiques. La surface réduite de ces principes d'affichage, ainsi que les limites du raisonnement humain, soulèvent des problèmes d'intégration de ces nouveaux modes de conduite. Dans une première partie, ce mémoire présente les différentes activités et les différentes tâches de l'operateur humain en salle de contrôle, ainsi que son comportement décisionnel face aux différentes situations auxquelles il se trouve confronté lors de la conduite de procédés. La fin de ce chapitre est consacrée à l'étude des outils d'assistance à l'operateur en salle de contrôle et a leurs différents modes d'intégration dans les systèmes de supervision. Ce travail porte aussi sur les problèmes d'interfaces graphiques homme-machine et énonce une démarche de conception de synoptique, ainsi que les règles de création et d'animation des images. Dans une troisième phase, une étude d'une usine minéralurgique par la méthode SADT (structured analysis and design technique) détermine les besoins informationnels nécessaires à la conduite centralisée de cette unité de fabrication. Le quatrième chapitre décrit la mise en place d'un système de supervision dans l'usine précédemment étudié, en appliquant au mieux l'ensemble des règles définies dans les deux premiers chapitres
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Amirabadi, Seyedshahabaldin. "Characterization of PLA-Talc films using NIR chemical imaging and multivariate image analysis techniques." Master's thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/29853.
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L’emballage joue un rôle important dans l’industrie alimentaire afin de maintenir la qualité des produits le plus longtemps possible. Les films de polymère sont largement utilisés dans l’emballage alimentaire et sont attrayants pour leurs propriétés exceptionnelles. Puisque les polymères à base de pétrole apportent des préoccupations environnementales, les polymères biodégradables tel que le PLA sont étudiés plus intensivement depuis quelques années considérant leurs propriétés écologiques. L’application de films renforcés permet, comparativement aux films simples, d’atteindre des fonctions spécifiques et d’améliorer leurs propriétés tel que l’étanchéité aux gaz. Toutefois, puisque la structure de ces films est plus complexe, le contrôle de qualité de ces derniers est plus difficile. Dans l’industrie, des méthodes hors-ligne sont très souvent utilisées pour effectuer le contrôle de qualité des films produits. Le contrôle est nécessaire puisque la variabilité de la matière première ainsi que le changement des conditions opératoires amènent des modifications qui changent considérablement les propriétés du film. Par conséquent, une inspection en temps réel ainsi qu’un contrôle des films de polymère est nécessaire sur la ligne de production afin d’obtenir un contrôle de qualité s’approchant de l’analyse en temps réel. Un système d’imagerie proche infrarouge (NIR) rapide et non-destructif est proposé pour caractériser les films biodégradables d’acide polylactique contenant du talc produits par extrusion-soufflage et utilisés pour l’emballage. Le but ultime est d’utiliser le système pour faire un contrôle de qualité sur la ligne d’extrusion ainsi qu’après le post-traitement termique, soit le recuit. Un ensemble d’échantillon de film de PLA contenant différentes concentrations en talc ont été fabriqués. Ces derniers ont ensuite été soumis à différentes conditions de recuit. Des images NIR ont été collectées avant la caractérisation des propriétés physiques et mécaniques ainsi que l’étanchéité aux gaz. Des techniques d’imagerie multivariées ont été appliquées aux images hyperspectrales. Celles-ci ont montré que la quantité de talc peut être déterminée et que l’information du spectre NIR permet de prédire les propriétés du film. Dans tous les cas, la méthode proposée permet de déterminer les variations dans les propriétés du film avec une bonne précision.Food packaging plays a great role in the food industry to maintain food products quality as long as possible. Polymer films are widely used in food packaging and also attract attention because of their outstanding advantages. Since petroleum-based polymers are known to cause environmental concerns, biodegradable polymers like PLA were studied more intensively in recent years due to their environmentally friendly properties. The application of reinforced films exceeds simple ones in achieving specific functions and enhancing their properties such as barrier properties. Since the films structures are more complex, quality control is more challenging. In industry, off-line methods are vastly used for quality control of the produced films while variability in raw materials and processing conditions substantially change the film specifications. Consequently, real-time inspection and monitoring of polymer films is needed on the production line to achieve a real-time quality control of the films. A fast and non-invasive near-infrared (NIR) imaging system is proposed to characterize biodegradable polylactic acid (PLA) films containing talc, and produced by extrusion film-blowing for packaging applications. The ultimate goal is to use the system for quality control on the extrusion line, and after a post-processing via thermal treatment (annealing). A set of PLA-talc films with varying talc contents were produced and submitted to annealing under different conditions. NIR images of the films were collected after which the samples were characterized for their physical, mechanical, and gas barrier properties. Multivariate imaging techniques were then applied to the hyperspectral images. It is shown that various talc loadings can be distinguished, and the information contained in the NIR spectra allows predicting the film properties. In all cases, the proposed approach was able to track the variation in film properties with good accuracy
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Villiéras, Frédéric. "Étude des modifications des propriétés du talc et de la chlorite par traitement thermique." Vandoeuvre-les-Nancy, INPL, 1993. http://docnum.univ-lorraine.fr/public/INPL_T_1993_VILLIERAS_F.pdf.
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Les conséquences d'un traitement thermique entre 400 et 1100°C sur les propriétés du talc et de la chlorite du gisement de Trimouns (Pyrénées, France) ont été étudiées par analyse thermique, diffraction des rayons X, spectroscopie IRTF, UV-visible, RPE, RMN, et par adsorption de gaz. Ces analyses ont permis de déterminer les mécanismes de réaction de la chlorite, les propriétés physico-chimiques des poudres calcinées aux différentes températures ainsi que les modifications de comportement en présence de minéralisateurs
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Micoud, Pierre. "Etude par RPE de l'influence du talc sur le vieillissement UV du polypropylène industriel." Toulouse 3, 2005. http://www.theses.fr/2005TOU30267.
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L'influence du talc sur le vieillissement UV du polypropylène (PP) industriel a été étudiée par Résonance Paramagnétique Électronique (RPE), à différentes températures d'irradiation et d'observation. Une synthèse bibliographique a été effectuée sur les corrélations structures-propriétés dans ces matériaux et sur les études de la photo-oxydation du polypropylène par RPE afin de présenter les divers niveaux d'organisation du PP et la nature des principaux radicaux d'oxydation. Le travail expérimental concerne l'analyse de l'évolution du comportement à l'oxydation des composites en fonction du temps d'irradiation et de la durée post irradiation. Les travaux effectués ont montré que la nature du talc et le taux de charge influent sur l'oxydation des composites PP-talc, notamment sur les proportions des différents radicaux d'oxydation piégés dans les composites. Le dégazage des "compounds" a permis de faire évoluer la recombinaison des radicaux d'oxydation et de proposer une limitation de la diffusion de l'oxygène sous l'effet d'une plus grande compacité des chaînes. Par ailleurs, l'évolution temporelle des radicaux, après l'arrêt de l'irradiation, a permis de mettre en évidence que l'oxygène atmosphérique joue un rôle primordial lors de l'oxydation des composites pendant les périodes d'obscurité. In fine, l'étude des spectres RPE à différentes températures a permis de jouer sur les cinétiques des réactions d'oxydation-recombinaison des radicaux et de mettre en évidence que les rapports d'oxydation de tous les échantillons deviennent équivalents au voisinage de la température de transition vitreuse du polypropylèneThe influence of talc on the industrial polypropylene UV ageing has been studied by Electron Spin Resonance (ESR), at different irradiation and observation temperatures. The bibliographic synthesis on the structures-properties correlations in these materials and on the studies of the polypropylene photo-oxidation by ESR gives an insight on the different organization levels and on the nature of main oxidation radicals. The experimental work is focused on the composites oxidation behaviour evolution with irradiation time and post irradiation duration. Results obtained are showing that the nature of the talc and the reinforcement ratio have an influence on the oxidation of the PP-talc composites, notably on the radicals proportion trapped inside composites. Modifications of oxidation and recombination reactions obtained by the devolatilisation of compounds have been interpreted by an oxygen diffusion restriction probably due to a bigger macromolecules compaction. Moreover, the evolutions with time of radicals after the irradiation stop have shown that the atmospheric oxygen plays a key role on the composite oxidation during the darkness periods. Finally, the study of ESR spectra at different temperatures has been used to modify the kinetic of oxidation-recombination reactions and demonstrate that oxidation ratio became equivalent around the polypropylene glass transition temperature
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Arnoux, Francis Majza Bernard. "Contribution à l'étude géologique des gisements de talc du massif du Saint-Barthélemy, Ariège." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37595639z.
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Etcheverry, Bernard Petit Jacques-Alain. "Adhérence, mécanique et tribologie des revêtements composites NiP - Talc multifonctionnels à empreinte écologique réduite." Toulouse : INP Toulouse, 2007. http://ethesis.inp-toulouse.fr/archive/00000431.
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Boutin, Alexandre. "Etude des conditions de formations du gisement de talc-chlorite de Trimouns (Ariège, France)." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30158/document.
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Le gisement de talc-chlorite de Trimouns est situé dans le massif nord-pyrénéen du Saint Barthélémy (Ariège, France). Il est l'objet d'une attention particulière pour ses ressources minérales exceptionnelles (tant par la qualité que l'abondance), et pour sa position stratégique dans l'histoire géologique des Pyrénées. Le but de cette étude est de caractériser les conditions de formation du gisement et de les intégrer dans le contexte géologique régional. Pour aborder cette problématique nous avons choisi trois grands axes d'étude : 1) au moyen de l'analyse cartographique et structurale, nous procédons à une description de la géométrie du gisement, et nous proposons une histoire des relations entre minéralisation et déformation ; 2) à l'aide d'analyses thermométriques via plusieurs méthodes, nous cherchons à définir quelle est l'histoire thermique enregistrée dans les différentes unités du gisement ; 3) avec des datations in situ sur un large panel de minéraux, nous positionnons des repères temporels sur plusieurs objets géologiques afin de dater le ou les épisodes minéralisateurs sur Trimouns. Les résultats obtenus expriment le caractère polyphasé du gisement, et ce pour les trois axes d'études suivis, déformation, thermicité et âge de la minéralisation. Les travaux sur les structures montrent que la minéralisation principale scelle une déformation probablement varisque, minéralisation qui se forme elle-même en contexte dynamique et qui est à son tour déformée. L'étude thermique met en évidence que la ou les minéralisations sont associées à un ou plusieurs événements froids, et qu'une empreinte thermique chaude est préservée dans les roches du toit et du mur du gisement. Les résultats géochronologiques montrent que la formation du talc et des chlorites à Trimouns est polyphasée et associée à une succession d'événements métasomatiques. L'Albien est l'évènement hydrothermal majeur mais des épisodes plus anciens sont enregistrés au Jurassique à Trimouns, voire au Permien dans d'autres gisements du massif et de l'ouest de la chaîne des Pyrénées. La synthèse de nos travaux nous permet de proposer un modèle de la formation du gisement de talc-chlorite de Trimouns. Ce modèle s'inscrit dans un contexte géodynamique extensif post-varisque que l'on peut mettre en relation avec les phénomènes extensifs pré-orogéniques pyrénéens du Crétacé (120-85 Ma). Ce contexte pré-orogénique est associé à l'exhumation du manteau, source probable du magnésium nécessaire à la formation du gisement. Nos travaux montrent également que le massif du Saint Barthélémy, et possiblement d'autres massifs nord pyrénéens semblables, ne sont pas des massifs "simplement" varisques mais qu'ils ont pu être profondément affectés par les évènements du cycle alpinThe Trimouns talc-chlorite deposit is located in the north Pyrenean Saint Barthelemy massif (Ariège, France). This deposit is remarkable in its minerals' quality and quantity as well as for its strategic position in the Pyrenees geological history. This study aims at understanding the formation conditions of the talc-chlorite deposit and at integrating them in the alpine pre-orogenic context. To this, we focus on three main themes : 1) Using geological and structural mapping studies, we describe the rocks and their organization as to estimate how much variscan and alpine orogenies affected them. 2) With thermometric analyses using different methods, we seek to define what is the thermal history recorded in the different units of the deposit. 3) Using in-situ dating on a wide range of minerals, we locate temporal references on various geological objects to document hydrothermal events. Achieved results demonstrate the polyphase caracteristics of the deposit, in the three focal areas used : deformation, thermal approach, and geochronology. Structural analysis shows that the mineralisation seals an other deformation, probably of the variscan period. This mineralisation is also formed in a dynamic context and then deformed as well. The thermal study highlights that mineralizations are associated with one or more cold events, and a hot thermal foot-print is preserved in the footwall and the hanging wall of the deposit. Dating results show that the formation talc and chlorite in Trimouns is multiphase, associated with succession of metasomatic events. The Albian event is the major hydrothermal event but older episodes are recorded in Jurassic at Trimouns and in Permian in other fields on the west-ern Pyrenees. The synthesis of our works allows us to propose a model of the formation of the Trimouns talc-chlorite deposit. This model is part of a post-Variscan extensive geodynamic context that can be related to the Pyrenean extensive pre-orogenic phenomena during Cretaceous period (120-85 Ma). This pre-orogenic context is associated with mantle exhumation, likely source of magnesium necessary for the formation of talc. Our studies also show that the Saint Barthelemy massif and possibly other similar north Pyrenean massif are not "simply" Variscan but have been deeply affected by the events of the Alpine cycle
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Boulingui, Jean-Eudes. "Inventaire des Ressources en Argiles du Gabon et leurs Utilisations Conventionnelles ou non dans les régions de Libreville et de Tchibanga." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0309/document.
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Les matériaux et minéraux argileux, abondent au Gabon. Les travaux pionniers révèlent la présence d’argiles rouges dans la série barrémienne de l’Agoula et d’argiles rouges à violettes dans la série néocomienne de Ndombo. Les argiles constituent une ressource précieuse et abondante qui a été largement valorisée tant en constructions traditionnelles de terre crue qu'en terre cuite en divers endroits du pays. Les présentes recherches sont initiées pour inventorier les ressources en différentes argiles facilement accessibles au Gabon, et dédiées à sélectionner des gisements à potentiel applicatif, selon la nature des argiles. Ce travail a été réalisé dans les régions de Libreville et de Tchibanga. Les échantillons prélevés font l’objet d’analyses macroscopique, microscopique, chimique, structurale et superficielle. Des essais de formulation font l’objet d’applications dans les domaines des briques, tuiles et celui des réfractaires. La croissance démographique de la République Gabonaise engendre une demande importante en divers matériaux locaux qui satisfassent les besoins de la vie courante. L’accent est mis sur les applications relatives aux terres cuites : briques, tuiles et carreaux. Des zones d'intérêt à potentiel économique sont identifiées. Les argiles de la région de Libreville, riches en kaolinites et illite sont intéressantes pour des applications en terre cuite. La caractérisation des propriétés minéralogiques des roches argileuses, est réalisée dans le but d'identifier les usages industriels les plus intéressants. Les caractérisations et les tests d’applications, identifient des matières premières pour la construction, la céramique, mais aussi dans bien d'autres domaines comme la pharmacologie (galénique), la papeterie, la cosmétique, l’agro-alimentaire, le caoutchouc, la peinture, le génie civil, le génie de l’environnement. Comme dans tous les pays d’Afrique Centrale, le développement durable passe inéluctablement par une maîtrise des ressources locales. La caractérisation fine des argiles du crétacé de Libreville est réalisée par : diffraction des rayons X, spectrométrie infrarouge à transformée de Fourier, microscopie électronique à balayage, détermination de la capacité d’échange cationique, granulométrie, analyses chimiques, indice de plasticité, test de céramique. Selon la diffraction des rayons X, ces argiles sont à kaolinite, et/ou illite et montmorillonite, quartz, ± muscovite, ± microcline, ± hématite, ± rutile, ± anatase. L’observation en Microscopie Electronique à Balayage et le traitement à l’Ethylène Glycol ou chauffé à 550°C analysé en DRX confirme la présence prépondérante de ces minérauxMaterials and clayey minerals abound in the Gabon. The pioneers works reveal the presence of red clays in the barrémian series of Agoula and red clays with violets in the neocomian series of Ndombo. Clays constitute a precious and plentiful resource which was widely beneficiated as well in traditional constructions of green clays as in terra-cotta in diverse places of the country. The present researches aim at inventorying the resources in various clays easily accessible in Gabon, and in the study of selection of deposits with application potential, according to the nature of clays. This work is carried on in the regions of Libreville and Tchibanga. The collected samples are the object of macroscopic, microscopic (tiny), chemical, structural and superficial analyses. Trials of formulation are the object of applications in the domains of bricks, tiles and refractories. The population growth of the Gabonese Republic generates a demand in diverse local materials satisfying the needs for the current life. The emphasis is put on the applications concerning terra-cottas: bricks, roof tiles and floor tiles. Zones of interest with economic potential are identified. Clays of the region of Libreville, rich in kaolinites and illite are interesting for applications in terra-cotta. The characterization of the mineralogical properties of the clayey rocks is realized with the aim of identifying the most interesting industrial uses. Characterizations and tests of applications, identify raw materials for the construction, the ceramic, but also in many other domains as pharmacology (galenic), paper industry, cosmetics, food-processing industry, rubber, paint, civil engineering and environment engineering. As in all the countries of Central Africa, the sustainable development passes inevitably by a control of the local resources. The fine characterization of clays of the Cretaceous of Libreville is realized by: X-ray Diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, determination of the cation exchange capacity, particle size analysis, chemical analyses, plasticity index, ceramic tests. According to the X-ray diffraction, these clays are mixtures of kaolinite, and/or illite and montmorillonite, quartz, ± muscovite, ± microcline, ± hematite, ± rutile ± anatase. The observation in Scanning Electron Microscopy and the treatment with Ethylène Glycol or heating at 550°C in XRD confirms the dominating presence of these minerals
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Santos, Sinara de Fátima Freire dos. "OTIMIZAÇÃO DO PROCESSO DE PURIFICAÇÃO DE BIODIESEL POR LAVAGEM A SECO "DRY WASHING"." Universidade Federal do Maranhão, 2010. http://tedebc.ufma.br:8080/jspui/handle/tede/914.
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The present work has the objective to purify the babassu and soy biodiesel using as adsorbent bentonite clay and talc, under monitoring by measurements of dielectric constant, index of acidity and humidity test. Initially, it was determined the quality of babassu oil and soy through physic-chemical, then was synthesized methylic and ethylic biodiesel. The talc and bentonite adsorbents were characterized for their surface area, pore diameter, MEV, XRD and FTIR. During the purification of biodiesel was used some percentages of adsorbent (0.5, 1, 2, 3 and 4% for 50 g of biodiesel) and adsorption times of 20, 30, 60, 90 and 120 min, under constant agitation and ambient temperature, the results were compared with the process of washing with acidified water, by monitoring with measurements of dielectric constant, acidity index and humidity test. The evaluation of the purification of biodiesel by dry washing, monitored by dielectric constants, got better answers than the process of washing with acidified water, with lower values of dielectric constant around 4.0% of adsorbent and 120 min of adsorption time .In relation to the index of acidity and the humidity test, samples of purified biodiesel with the adsorbent are in accordance with the specifications of the National Agency of Petroleum, Natural Gas and Biofuels (ANP). Therefore, it is considered that the methodology for dry washing, as well as monitoring by dielectric constant, is feasible as a method of purification and monitoring, respectively, using as references the results of conventional purification process.
O presente trabalho tem o objetivo de otimizar as condições do processo de purificação a seco de biodiesel, utilizando como adsorvente a bentonita e o talco, sob monitoramento por medidas de constante dielétrica, índice de acidez e teor de umidade. Inicialmente, foi determinada a qualidade dos óleos de babaçu e soja através de testes físico-químicos, em seguida foi sintetizado o biodiesel metílico e etílico. Os adsorventes foram caracterizados por adsorção de nitrogênio, microscopia eletrônica de varredura, difração de raios-X e infravermelho. Durante a purificação do biodiesel utilizou-se várias percentagens de adsorventes (0,5, 1, 2, 3 e 4% por 50 g de biodiesel) e tempos de adsorção de 20, 30, 60, 90 e 120 min, sob agitação constante e temperatura ambiente, os resultados foram comparados com o processo de lavagem com água acidificada, através do monitoramento com medidas de constante dielétrica, índice de acidez e teor de umidade. A avaliação da purificação do biodiesel por lavagem a seco, monitorada por constantes dielétricas, obteve respostas melhores que o processo de lavagem com água acidificada, com menores valores de constante dielétrica em torno de 4,0 % de adsorvente e 120 min de tempo de adsorção. Em relação ao índice de acidez e o teor de umidade, as amostras de biodiesel purificadas com os adsorventes, estão de acordo com as especificações da Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP). Portanto, considera-se que a metodologia por lavagem a seco, bem como, o monitoramento por constante dielétrica, é viável como método de purificação e monitoramento, respectivamente, usando como referências os resultados obtidos do processo de purificação convencional.
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Howe, Harriet. "The effect of solid solution on the stabilities of selected hydrous phases during subduction." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/the-effect-of-solid-solution-on-the-stabilities-of-selected-hydrous-phases-during-subduction(c1c440aa-e51c-49e3-beda-558bd2b1cc4a).html.
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Previous studies on complex chemical systems, approximating enriched ultramafic compositions, have shown that the stability fields of certain phyllosilicate minerals may be shifted through solid solution. This project focuses on three hydrous phases predicted to play an important role in water transfer and storage during subduction. Talc, and at higher pressures the 10 A phase, are expected form in enriched abyssal peridotite within the cold interior of a lithospheric slab, whilst the sodic amphibole eckermannite is expected to be present in the overlying hydrated basalt. Multi-anvil and piston cylinder press experiments in the FeO-MgO-SiO2-H2O (FMSH), NaO-MgO-Al2O3-SiO2-H2O (NMASH), and MgO-Al2O3-SiO2-H2O (MASH) systems have sought to determine the effect of solid solution on the stability on talc and the 10 A phase, with comparison to the end-member MgO-SiO2-H2O (MSH) system. The reaction talc + H2O = 10 A phase has been bracketed in the MSH system at 4.8 GPa/560 ˚C and 5 GPa/640 ˚C, confirming the estimated reaction position from Pawley et al. (2011). Previously unknown values for the entropy and enthalpy of formation of the 10 A phase have been calculated as DeltaHf = -6172.02 kJ and DeltaSf = 320.075 JK-1. At 2 GPa talc containing 0.48 apfu Fe2+ breaks down in the divariant field talc + anthophyllite + quartz + H2O from ~550 ˚C, initiating talc dehydration at temperatures ~270 ˚C lower than in the MSH system. At 4 GPa Fe-bearing talc breaks down in the divariant field talc + enstatite + coesite. A run at 5.2 GPa and 555 ˚C produced 10 A phase containing 0.48 apfu Fe2+. Between 575 ˚C and 600 ˚C at 6.5 GPa phase reversal experiments bracketed the initiation of Fe-bearing 10 A phase dehydration in the divariant field 10 A phase + enstatite + coesite + H2O, corresponding to a reduction in thermal stability of around ~100 ˚C compared to the end-member. The relative positions of the talc and 10 A phase dehydration reactions suggest the latter is able to accommodate greater Fe substitution, and is therefore more stable in the FMSH system. The assemblages 10 A phase + enstatite + coesite + jadeite and 10 A phase + enstatite + pyrope + coesite, were synthesised in the NMASH and MASH systems, respectively. Compositional analysis indicates that the 10 Å phase in these samples contains < 1 weight % Al2O3, with negligible Na. This suggests that Al3+ substitution in talc and the 10 Å phase is unlikely to exert the same stabilising effect observed in a number of other phyllosilicates. Eckermannite was produced in further NMASH experiments at 6.2 GPa. Compositional and structural analysis indicates near-full A-site occupancy and a composition close to that of the end-member, deviating through a minor binary exchange towards Mg-katophorite. This exchange is proposed to stabilise eckermannite to high pressures, beyond previously published limits for sodic amphibole stability. Updated stability fields for talc, the 10 Å phase, and eckermannite were applied to a thermal model for subduction. This predicts that 10 Å phase containing 0.48 apfu Fe2+ may be stable to depths of ~260 km, compared to ~280 km for the end-member. With increasing pressure and temperature Fe-bearing 10 Å phase will dehydrate across a depth range, resulting in either total de-volatilisation, or transfer to other stable high pressure hydrous phases enabling the transport of water to the deeper regions of the mantle.
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Yoshikawa, Shinichi. "Effects of adding foreign particles on crystallization and physical properties of fat-based products." Kyoto University, 2016. http://hdl.handle.net/2433/216160.
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(1) Yoshikawa, S., Kida, H. & Sato, K. Promotional effects of new types of additives on fat crystallization. J. Oleo Sci. 63(4), 333–345, © 2014 Japan Oil Chemists’ Society, Tokyo., (2) Yoshikawa, S., Kida, H. & Sato, K. Fat crystallization with talc particles is influenced by particle size, concentration, and cooling rate. Eur. J. Lipid Sci. Technol. 117(6), 858–868, © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim., (3) Yoshikawa, S., Kida, H., Matsumura, Y. & Sato, K. Adding talc particles improves physical properties of palm oil-based shortening. Eur. J. Lipid Sci. Technol., DOI: 10.1002/ejlt.201500283 (in press), © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Kyoto University (京都大学)
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新制・論文博士
博士(農学)
乙第13044号
論農博第2837号
新制||農||1044(附属図書館)
学位論文||H28||N5008(農学部図書室)
33036
(主査)教授 松村 康生, 教授 裏出 令子, 教授 安達 修二
学位規則第4条第2項該当