Polypropylene continues to be the mainstream choice thermoplastic for automotive applications. In many applications PP is filled with mineral fillers for improvement of properties. Biobased natural fillers or fibres are attractive materials to reduce the weight because of the low specific gravity of the biobased materials compared to the mineral fillers. Our group has done extensive research on the development of wheat straw fiber in thermoplastics in the past years. It is very important to understand the behaviour of single fillers on composites before studying the effects of mixing fillers or fibers (hybridization). The objective of this study is to evaluate and compare systematically the effects of wheat straw and mineral fillers in the polypropylene matrix. The study includes two types of wheat straw (WS) categorized based on their size (fine WS and medium WS) and three different types of natural minerals (Talc, Mica and Wollastonite). Three types of polypropylene (PP), Homopolymer PP, High Impact Copolymer PP and Homopolymer-Copolymer Blend PP, were investigated as the matrix. This study also evaluates the effect of combining two fillers (WS and mineral filler) in the hybrid composite. The fillers were formulated in three different percentages (20, 30 and 40wt %) and compounded via extrusion. Samples for all formulations were prepared by injection molding. The mechanical properties (flexural modulus and strength, tensile modulus and strength, impact strength), water absorption and density were measured. The properties of hybrid composites were evaluated by varying the amounts of two fillers at 10wt%-20wt%, 15wt%-15wt% and 20wt%-10wt% each, keeping the overall filler content constant at 30wt%. The effect of type of filler, filler size and filler content were critical in this work. The results obtained from this study indicated that filler type and filler content greatly influenced the mechanical properties and water absorption characteristics of the composites. The flexural modulus increased with increasing filler content. It was interesting to observe that though the impact strength decreased with the addition of fillers, increasing the filler content from 20 to 40 wt% did not affect the property. With respect to all fillers, wollastonite improved the mechanical properties significantly. Increasing the amount of WS content reduced the composite’s resistance to water absorption. Among mineral fillers, mica showed significantly higher percentage gain in weight with water absorption. Combination of fillers at varying percentages did not have any synergy effect on the mechanical behaviour of the composite. The percentage increase in weight with water absorption was observed to be increasing with increasing WS content in hybrid composites, but significantly lower than pure WS composites. The morphological study on WS composites revealed improved interaction of filler with homopolymer and polypropylene blend.

Polymeric depressant adsorption on the surface of talc was investigated using in situ Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) Spectroscopy. The polymeric depressants investigated were an unmodified polyacrylamide (Polymer-N) and a hydroxyl substituted polyacrylamide (Polymer-H), an unmodified dextrin (Dextrin WY) and a hydroxylpropyl substituted dextrin (HP Dextrin), and carboxymethyl cellulose (CMC). The main objectives of this study were to evaluate the thermodynamic properties of adsorption, the kinetics of adsorption and desorption, and the mechanisms driving adsorption. / Thesis (PhDApSc(MineralsandMaterials))--University of South Australia, 2007.

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.

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.

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.

(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. / 京都大学 / 0048 / 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 / Doctor of Agricultural Science / Kyoto University / DFAM

Les solides divisés, ou poudres, sont très utilisés dans de nombreux secteurs industriels. Dans l'industrie pharmaceutique les poudres peuvent être granulées et/ou comprimées pour la mise en oeuvre de formes galéniques solides et elles peuvent également être dispersées pour formuler des suspensions buvables par exemple. En cosmétique, le mélange des poudres ou la mise en suspension sont des étapes cruciales pour certains produits. Le secteur agro-alimentaire génère et formule de nombreux produits sous la forme de solides divisés. Dans le domaine des peintures, la dispersion des pigments dans la phase liquide est primordiale. Dans ces différents cas, les interactions interfaciales solide-solide et solide-liquide régissent très fortement les différents procédés industriels. C'est le cas de la dispersion d'une poudre dans un liquide qui est fortement influencée par l'énergie interfaciale entre la poudre et le liquide, composante directement liée à la tension de surface du liquide et l'énergie de surface de la poudre par l'intermédiaire de l'angle de contact (équation de Young). Dans cette étude, la dispersion de talc, hydrophobe, largement utilisé dans l'industrie notamment papetière, est étudiée dans une phase aqueuse. Afin de modifier les interactions solide-liquide (et solide-solide), la surface du talc est modifiée par enrobage à sec avec de la silice nanométrique hydrophobe (Aérosil® R972). Pour cela, deux dispositifs d'enrobage ont été utilisés : un mélangeur à haut cisaillement (Cyclomix®) et un broyeur à billes planétaire (BBP). L'objectif de ce travail est d'étudier l'influence des modifications des interactions solide-liquide sur la dispersibilité des particules. Les modifications de surface des particules enrobées ont été analysées par la méthode de la goutte posée, par montée capillaire, par chromatographie gazeuse inverse (CGI) et par sorption dynamique de vapeur (DVS). Ces modifications ont ensuite été mises en parallèle avec la vitesse de dispersion des particules dans l'eau. Des relations ont été établies entre la vitesse de dispersion des particules et le travail d'adhésion particules / eau. En plus des interactions solide-liquide, le passage dans les appareils d'enrobage modifie d'autres paramètres du talc comme sa densité, sa rhéologie, sa flottabilité etc., autant de paramètres modifiant également sa dispersibilité. Enfin, la puissance d'agitation de la phase aqueuse est un paramètre également étudié. / Powder technology concerns the phenomena encountered in industrial processes involving divided solids. Such processes are found in the pharmaceutical, cosmetics, and food industries (where many products are based on powders; tablets, granules, suspensions), and in the paint industry where solid pigments are dispersed in liquids. In particular this thesis examines the dispersion of powders in liquids which depends strongly on the interactions between solids and liquids and can be assessed by the solid-liquid interfacial energy. This energy is directly linked to the surface tension of the liquid and the surface energy of the solid through the contact angle in the Young equation. The contact angle is used to calculate the work of adhesion between a powder and a liquid and characterises the wettability of the powder. Talc powder, mainly used in paper industry, is used in this study. The surface of talc powder has been modified by dry coating with hydrophobic nano-silica (Aerosil® R972) using two different devices: a high shear mixer (Cyclomix®), and a planetary ball mill. The aim being to observe the effect of surface modification on the wettability and surface energy of coated talc particles and the effect of these surface energy changes on the dispersability of particles. Different parameters have been considered: the concentration of hydrophobic silica, the duration of processing without silica and with 3 % silica. Surface modifications have been assessed using the sessile drop method, capillary rise, inverse gas chromatography (IGC) and dynamic vapour sorption (DVS). This study shows that not only the surface wettability is modified by the treatment of particles in the coating devices, but also their physical characteristics such as their bulk density, their rheology, their buoyancy and thus their dispersibility. Finally, a study is made of the effect the stirring power of the aqueous phase on the dispersibality of talc powders coated with different concentrations hydrophobic silica.

Ces travaux de thèse ont porté sur le développement de nouveaux engrais à relargage contrôlé grâce à la mise en œuvre d’un procédé de mechanosynthèse à partir de mélanges contenant des composés lamellaires soit naturels (montmorillonite, talc et chrysotile) soit synthétiques (les Hydroxydes Doubles Lamellaires (HDL) à base de Mg, d’Al et de Fe) et de monohydrogénophosphate de potassium. Ce sel est déjà utilisé en agriculture en tant que fertilisant conventionnel. Toutefois sa forte solubilité en solution aqueuse induit des pertes importantes lors de l’épandage via des procédés de lixiviation, de volatilisation ou encore de fixation dans les sols, limitant ainsi l’efficacité des nutriments pour les plantes. Il est alors nécessaire d’en utiliser des quantités excessives pour observer une efficacité en agriculture. Aussi la principale alternative est de contrôler l’apport en éléments venant d’une part du sel soluble mais également des constituants chimiques des matrices lamellaires impliquées. Une telle approche pourrait réduire les coûts en permettant une fertilisation accrue tout en en diminuant la solubilité des ions impliqués. La méthode utilisée consiste à broyer les réactifs ensemble en modifiant les conditions de broyage utilisées. Afin d’évaluer les modifications structurales induites par le broyage, les échantillons obtenus sont caractérisés à l’aide de différentes techniques de caractérisation du solide, en fonction des éléments chimiques impliqués. La diffraction des rayons X (PXRD), la microscopie électronique à balayage couplé avec un analyseur (SEM-EDX) et les méthodes spectroscopiques SSNMR, FTIR, RAMAN, RPE…) se sont avérées pertinentes pour réaliser le suivi des réactions de mechanosynthèse et mettre en évidence une amorphisation des matrices précruseurs et éventuellement la formation de nouvelles phases cristallisées. La microscopie montre sytématiquement une modification importante de la taille des particules avec perte de la morphologie des matériaux précurseurs et parfois apparition de nouveaux cristaux de forme bien définie ayant une composition chimique différente. Grâce à la spectroscopie RMN à l’état solide il est possible de mettre en évidence de fortes modifications de l’environnement chimique après mechanosynthèse, suggérant la formation de composés métastables impliquant des cations métalliques issus des phases lamellaires, du phosphore et de l’oxygène. Les composés obtenus ont ensuité été étudiés dans des conditions de relargage mettant en évidence des propriétés de realargage contrôlé quelle que soit la matrice lamellaire précurseur impliquée dans le procédé. La vitesse de relargage des nutriments est influencée par la nature et la composition chimique de la matrices de départ, sachant qu’en fonction de leur composition chimique des produits différents peuvent être formés. / The present work describes the development of slow release fertilizers from the mechanochemical activation of of natural (montmorillonite, talc, chrysotile) and synthetic (Layered Double Hydroxides (LDH) MgAl and MgFe) lamellar matrix mixtures with potassium monohydrogen phosphate. This salt is used in agriculture as a conventional fertilizer and is highly soluble in aqueous solution, which implies large losses due to leaching processes, volatilization or even fixation in the soil, limiting the efficiency of the nutrients for the plants. Due to these characteristics, there is a need to apply large quantities of these products in agriculture. Therefore, the main idea is to control the supply of both the elements coming from the soluble salt as well as the constituting elements of the lamellar matrices. Such approach could reduce costs with exacerbated fertilization, potentiating the use of the products and decreasing the solubility of the ions involved. The methodology used basically consists of the milling of the reagents varying the processing conditions. For the characterization of the samples, several techniques were used according to the nature of the compounds involved. Particularly, PXRD, SEM / EDX and spectroscopic (SSNMR, FTIR, RAMAN, EPR…) techniques proved to be highly efficient for the monitoring of the mechano-chemical reaction, and to highlight the amorphization of the precursors and/or the formation of a distinct crystalline phase. SEM/EDX showed after the mechanochemical activation the changes in particle size, the disappearance of precursor morphologies, and the formation of particles with distinct morphologies and different chemical composition. Using solid state NMR measurements significant changes in the chemical environments involved were evidenced, suggesting the formation of metastable compounds between metal cations from the lamellar matrices, phosphorus and oxygen, as well as other possible compounds as products. After the mechanochemical reaction, in the nutrient release assays, the slow release behavior was observed for all the matrices analyzed. The release rate can be influenced by the chemical composition of the starting matrices, since each matrix can produce similar and distinct products, for example, SiO2 from natural clays which is not possible in the LDH products.

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 alpin. / The 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.

This thesis is focused at possibilities of preparation and characterization of XRD-amorphous delaminated and dehydroxylated talc phase – meta-talc, which can have its potential application and a starter material for a preparation of magnesium-silicate analogues of geopolymers. Changes in structure and morphology of talc ore were observed during this work. For the purposes of this research, two various talc ores – chloritic and dolomitic were examined. Whole process of meta-talc preparation was examined with whole scale of instrumental techniques such as X-ray diffraction, simultaneous thermogravimetric a differential thermal analysis, infrared spectroscopy, scanning electron microscopy or laser analysis of particle size. Meta-talc can be obtained via mechanochemical activation of talc ore with subsequent calcination. Mechanochemical treatment lead to destruction of original crystal structure and breaking of original bonds, i.e. the product of this treatment was almost amorphous and delaminated. Most of hydroxyl groups were converted to molecules of water which remained adsorbed or coordinated in ore structure. These molecules were removed during calcination step.