The compaction behaviour of boehmite has been studied under isothermal conditions, with special emphasis devoted to hot pressing in the temperature range 300 to 600°C. The present work indicates that it is possible to produce a hard dense compact under certain conditions. However, the behaviour of the material during reactive hot pressing appears to be more complicated than can be explained by simple sintering or kinetic theories. To aid in understanding the mechanisms of compaction during a phase transformation, the behaviour of the system during reactive hot pressing was studied from a purely phenomenological point of view, a viscoelastic model. By using viscoelastic theory it is possible to relate ideal elastic and energy-absorbing or damping viscous parameters to the behaviour of boehmite during R.H.P. While the apparent compact density varied as a complex function of temperature, it was found that the overall compaction behaviour of boehmite could be adequately described by a second order linear differential equation, which in turn could be related to a combination of elastic (displacement sensitive) and viscous (strain rate sensitive) components. The viscous nature of the powder during R.H.P. reached a maximum value just before the boehmite to gamma transition (380 to 443°C), suggesting that strong particle interaction was occurring. It is anticipated that R.H.P. from 380 to 443°C will lead to the most favourable particle rearrangement for producing a hard gamma phase at 500°C. In producing the "hard phase" it was important to maintain a critical water concentration. Approximately 4% retained water was necessary for forming a hard dense compact. On the other hand in the presence of an excessive water vapor pressure, the unreacted boehmite powder appeared to transform directly to alpha alumina, resulting in a friable compact. Thus the need for maintaining the correct vapor pressure during R.H.P. is essential. Production of the "hard phase" material at 500°C appears promising as an intermediate step in producing strong translucent bodies upon subsequent sintering at 1000°C. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

A compressive creep study of cold compacted colloidal boehmite has been carried out during the dehydroxylation reaction. The creep tests were made as a function of temperature, applied stress and the relative density of the cold compact. The activation energy for creep has been found to be 9.1 ± 1.5 Kcal/mole. The total creep rate was due to the stress associated with the neck formation at the points of contact and the applied stress. The creep rate is proportional to the applied stress. The final form of the total creep rate equation is ė =[0.144 exp ( formula omitted )+2.2x10ˉ⁷σ] sec ˉ¹. Electron photomicrographs of fractured surfaces of deformed specimens revealed the presence of contact points in the aligned fibers, confirming the existence of the driving force for shrinkage. Equations relating the change in length and the strength of a compact with time have been tested with the experimental data, which indicated that the rate controlling mechanism may be volume diffusion for the creep process. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

The 53 million gallons (240,000 tons) of nuclear waste stored at the Hanford site comprises approximately 60% of the nation¡¯s legacy nuclear waste. Previously, processing of the saltcake phases of tank wastes dominated disposal efforts at Hanford. Interest is now being directed at the processing and pretreatment of the sludge phases of the waste. These sludges, consisting of complex combinations of insoluble metal compounds, present many challenges. This thesis deals with experimentation pertaining primarily to aluminum chemistry and the role it plays in pretreatment of Hanford waste sludge. Included is a statistical analysis of an inventory of components within Hanford tanks. A recipe was followed to produce a simulant sludge for further experimentation. The solubility of the aluminum species, gibbsite, thought to be the most common aluminum species in the Hanford tanks, was studied. In addition, the reaction by which gibbsite is transformed to a much less soluble phase, boehmite, was studied in depth. Gibbsite¡¯s transformation to boehmite begins at about 200 ¡ÆC, a temperature higher than that seen by Hanford tanks. However, recent literature suggests that it may be converted to boehmite at lower temperatures. A study of the rate of boehmite formation at temperatures ranging from 80 to 150 ¡ÆC using caustic concentrations of 1.5, 3, and 5 molal is reported. In such a way, the effects of both temperature and caustic loading on the rate of boehmite formation were sought. It was determined that boehmite formed readily at temperatures 120 ¡ÆC and higher. These data supplement existing aluminum chemistry knowledge and will increase the efficiency with which sludge pretreatment and disposal procedures are designed.

Ces travaux portent sur la précipitation de boehmite AlOOH, qui est le précurseur de l’alumine γ – Al2O3, support catalytique utilisé dans de nombreux procédés de raffinage. Le contrôle de la porosité de ces particules est crucial afin de minimiser les limitations par transfert de matière et de chaleur et d’améliorer la performance des catalyseurs. La porosité de l’alumine provient en partie de l’étape de précipitation de boehmite. Elle est conservée du fait de la topotacticité de la transformation boehmite - alumine. La boehmite est obtenue par précipitation de sels d’aluminium. L’effet des paramètres physico-chimiques, tels que la température et le pH, sur les propriétés du matériau a été largement étudié dans la littérature. Cependant, peu d’études ont permis la mise en évidence des phénomènes régissant l’agrégation durant le procédé de précipitation. L’objectif de cette étude est de comprendre et de quantifier les paramètres de précipitation influençant l’agrégation de la boehmite au cours de sa synthèse. La précipitation de la boehmite a été réalisée dans deux types de dispositifs de précipitation. Le dispositif double-jets, utilisé à l’échelle industrielle, induit des conditions non-homogènes de sursaturation et de fraction volumique en particules, tant temporellement que spatialement. La deuxième méthode de précipitation de boehmite utilise des pré-mélangeurs (Hartridge-Roughton et Y), dans lequel le micro-mélange et la sursaturation initiale sont finement contrôlés. La sursaturation a été calculée au cours de la précipitation sur la base du modèle thermodynamique de Pitzer. Celle-ci est significativement plus importante dans le dispositif pré-mélangeur. L’effet des paramètres opératoires a été mis en évidence sur les propriétés texturales de la boehmite via des caractérisations ex situ (DRX, adsorption-désorption d’azote par méthode BET, cryo-MET). Les matériaux issus du dispositif double-jets présentent une porosité d’autant plus aérée que la sursaturation est faible, et il existe une valeur seuil de sursaturation au-delà de laquelle la porosité n’est plus impactée par ce paramètre, comme c’est le cas dans le dispositif pré-mélangeur. Dans ce cas, aucun autre paramètre opératoire n’affecte la texture du matériau. Ces résultats mettent en évidence des mécanismes d’agrégation dépendant directement de la sursaturation. Des techniques de caractérisation originales ont par ailleurs été mises en place afin de suivre la dynamique de l’agrégation. L’analyse par diffusion multiple de la lumière a permis de mettre en évidence des cinétiques d’agrégation différentes, directement corrélées à la porosité, et ce avant les étapes de filtration-lavage-séchage. Une analyse fine des états d’agrégation a été réalisée in situ par SAXS à rayonnement synchrotron. Cette étude a permis de proposer différents scénarii des mécanismes d’agrégation. Il apparaît que les fibres de boehmite s’agrègent de manière beaucoup plus aérée à faible sursaturation. Une porosité visée pourrait ainsi être obtenue par un contrôle fin de la sursaturation. Enfin, une première approche de modélisation par bilan de population a été développée afin de décrire les processus de formation des fibres et d’agrégation secondaire. / This work focuses on the precipitation of boehmite AlOOH, which is the precursor of alumina γ – Al2O3, used as catalyst support in many refining processes. The control of the porosity of these particles is crucial to minimize the limitation by mass and heat transfer, and improve catalysts performance. Alumina porosity mainly comes from precipitation step. It is conserved due to the topotacticity of boehmite – alumina transformation. Boehmite is obtained by precipitation of aluminum salts. The effect of physical and chemical parameters, such as temperature and pH, on the material properties has been extensively studied in the literature. However, few studies allowed the identification of the phenomena governing aggregation during the precipitation process. The objective of this study is to understand and quantify the precipitation parameters influencing boehmite aggregation, dynamically. The precipitation of boehmite was performed in two types of precipitators. The double-jet device, used at industrial scale, has non-homogeneous conditions of supersaturation and particle volume fraction, both temporally and spatially. The second boehmite precipitation method uses micro-mixers (Hartridge-Roughton and Y), wherein the micro-mixing and initial supersaturation are finely controlled. Supersaturation was calculated during the precipitation on the basis of Pitzer thermodynamic model. This one is significantly higher in the micro-mixing device. The effect of process parameters has been highlighted on boehmite textural properties via ex situ characterizations (XRD and nitrogen adsorption-desorption by BET method, cryo-TEM). Materials resulting from double-jet device develop loose porosity especially for low supersaturations. There is a supersaturation threshold value beyond which the porosity is fixed, as is the case in micro-mixer device. In this case, no other process parameter affects material texture. These results highlight aggregation mechanisms directly dependent on supersaturation. Original characterizations techniques have also been put in place to monitor aggregation dynamically. Multiple light scattering analysis allowed highlighting different aggregation kinetics, directly correlated to the porosity, before filtering, washing and drying steps. A detailed analysis of aggregations states was performed by synchrotron radiation SAXS in situ. This study allowed proposing different aggregation mechanisms scenarios. It appears that boehmite fibers aggregate in a much looser way at low supersaturation. Targeted porosity could thus be obtained by fine control of supersaturation. Finally, a first approach of population balance modeling has been developed to describe fibers formation and aggregation process.

No description available.

In this study, organic-inorganic hybrid materials were prepared from polyurethane and boehmite. It was achieved by polymerizing monomers in the presence of functional nano-particles of boehmite with cyanate groups. The produced polyurethane organic-inorganic hybrid materials with enhanced mechanical properties were used for coating applications. Plate-like boehmite nano-particles were produced by hydrothermal process from aluminum hydroxide which was first ground in a high energy ball-mill, and then, processed hydrothermally under pressure and high temperature in a reactor. The surface morphology and crystal structure of boehmite were investigated by Scanning Electron Microscopy and X-Ray Diffraction analyses, respectively. The molecular structures of boehmite particles were investigated by Fourier Transform infrared spectroscopy. Furthermore, Brunauer-Emmett-Teller analysis and Photon Correlation Spectroscopy analysis were carried out to determine the surface area and the size of particles. Then, plate-like boehmite nano-particles were functionalized by the reaction of their hydroxyl groups with 1,6-hexamethylene diisocyanate and 4,4&rsquo / -methylene diphenyl diisocyanate. Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Differential Thermal Analysis-Thermal Gravimetric Analysis, and elemental analysis were performed for both functionalized and non-functionalized particles to confirm the functionalization of the particles. The polyester polyol used in the production of polyurethane was synthesized from 1,4-butanediol and adipic acid (PE-PO-1), and phthalic anhydride (PE-PO-2). Molecular structure of the polyester polyols was confirmed by Fourier Transform Infrared Spectroscopy analysis and molecular weight of the polymers were determined by end group analysis. Then, the produced functionalized nano-particles and polyester polyols were used for producing polyurethane organic-inorganic hybrid materials. Furthermore, polyurethane polymer and polymer-nonfunctionalized boehmite organic-inorganic hybrids were also synthesized for property comparison. Hardness, impact resistance, scratch resistance, abrasion resistance, and gloss property of the samples were determined. It was observed that mechanical properties of organic-inorganic hybrid materials improved significantly. The hardness of the PU produced with PE-PO-1 increased from 82 to 98 Persoz, and the hardness of the PU produced with PE-PO-2 increased from 52 to 78 Persoz when one weight percentage functionalized boehmite was used. The impact resistance of the coatings was found to depend on the type of the polyols used in PU but not in the inorganic component. Therefore PE-PO-2 used PU has higher impact resistance than PE-PO-1 used PU. Scratch resistance of the coatings improved from 2B to 2H when using functionalized boehmite. Abrasion resistance of PUs produced with PE-PO-1 increased from 2 to 10 l/micrometer and abrasion resistance of PUs produced with PE-PO-2 increased from 12 to 20 l/micrometer by addition of functionalized boehmite.

L'objectif de ces travaux de thèse a été de développer un système de protection anticorrosion sur alliages d'aluminium 2024 en combinant le procédé sol-gel à la technique de dépôt par électrophorèse (ou EPD). Dans cette optique, nous nous sommes intéressés à l'évaluation du couplage de la technique de dépôt par EPD, technique offrant l'avantage de réaliser des dépôts à la fois épais, couvrants et homogènes en épaisseur même sur pièces complexes, au procédé sol-gel, bien connu et fortement prometteur pour développer des revêtements anti-corrosion performants. Le travail de thèse s'est focalisé sur la réalisation de dépôts par électrophorèse à partir d'un sol hydride, chargé ou non en particules de boehmite (NPs), et sur l'étude de différents paramètres électrophorétiques (paramètres à la fois liés au medium et au procédé lui-même). Nous avons ensuite cherché à connaître les propriétés des revêtements mis en forme par EPD (propriétés anti-corrosion et perméabilité des films en particulier) via des caractérisations électrochimiques (étude par Spectroscopie d'Impédance Electrochimique (SIE), électrode à disque tournant (EDT)). Ces dernières études ont été réalisées sur alliage d'aluminium 2024 (AA2024), dans un premier temps, puis sur substrat modèle (substrat inerte tel que l'or (Au)) dans le but d'évaluer la réponse électrochimique intrinsèque du revêtement. Dans un premier temps, nous avons pu obtenir par EPD et de façon répétable, des dépôts homogènes et d'épaisseurs contrôlées sur AA2024 et Au. La croissance de ces dépôts est à la fois le résultat de la migration des NPs et de l'augmentation du pH interfacial, provoqué par l'électrolyse de l'eau mais responsable, à terme, d'une redissolution du film. Ce phénomène de redissolution/décollement a pu néanmoins être limité en modulant la forme du signal électrique (application d'un potentiel périodique). Aussi, nous avons démontré que la quantité de NPs présente dans le sol précurseur joue un rôle clé dans les épaisseurs de dépôts obtenues (des épaisseurs dans la gamme 7 à 20 µm ont pu être atteintes en doublant uniquement la concentration en NPs vectrices dans le sol précurseur). En ce qui concerne le comportement électrochimique des différents systèmes mis en forme par EPD, la modélisation des spectres SIE, via le logiciel Z view, montre que les propriétés barrières des revêtements chargés tendent à se dégrader plus vite avec le temps d'immersion que pour ceux obtenus sans particules. Nous avons finalement cherché à mesurer la perméabilité des films électrophorétiques via un dispositif de type électrode à disque tournant (EDT). Les résultats obtenus ont montré que le coefficient de perméabilité kf des films électrophorétiques évolue fortement, dès les premières heures d'immersion, et augmente d'autant plus que le système est chargé en NPs. / The realisation of organic/inorganic coatings on metal substrates, prepared by sol-gel route and shaped by electrophoretic deposition (EPD), is a new combined process which has been the subject of only few studies. EPD technique offers an easy control of the thickness and morphology of the film even on substrates of complex shape, which are the main challenges for all kinds of deposition techniques used in various industrial fields. Moreover, sol-gel route has been extensively studied as a potential alternative pre-treatment to prepare a variety of materials with versatile applications from anti-corrosion to anti-wear. So, coupling these two techniques is one way to obtain both benefits on a same system. In this work, the electrophoretic deposition was performed on AA2024 from an aqueous sol suspension containing sol-gel boehmite nanoparticles (NPs). The influence of the applied voltage and deposition time on the deposit thickness was studied. The effect of the concentration of NPs, added in the precursor sol, on the thickness was also investigated. It is shown that an increase in the applied voltage and deposition time increased the thickness of the deposit film (from 2 to 11 µm). However, for a same voltage, increasing the concentration of NPs in the precursor sol, progressively increases the coating thickness (Figure 1.) and appears as a key parameter to adjust the coating thickness. Finally, it was demonstrated that a perfect control of the microstructure and the deposit thickness was achievable, thanks to both EPD parameters and sol properties. The electrochemical properties of the electrophoretic coatings are then studied by Electrochemical Impedance Spectroscopy (EIS) and by rotating disk electrode and showed that the permeability of the coatings increased with the particles concentration.

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

Óxidos e hidróxidos de alumínio vêm sendo alvo de estudos no Laboratório de Matérias-Primas Particuladas Prof. Pérsio de Souza Santos (LPSS) nas últimas seis décadas. Várias rotas de síntese de mono- e tri-hidróxidos foram pesquisadas, bem como as transformações térmicas desses materiais em aluminas de transição e alumina-alfa. Mais recentemente, a síntese de boemita a partir do tratamento hidrotérmico de gibsita vem sendo o principal objeto dos estudos realizados no LPSS. Nesta Tese, a síntese hidrotérmica de boemita a partir de uma gibsita Bayer comercial foi estudada. Os cristais produzidos foram caracterizados por difração de raios X (DRX), por análises térmicas (TGA e DTA) e por microscopia eletrônica de varredura (MEV). Diferentes morfologias de cristais de boemita foram obtidas - cristais com dimensionalidade \"3D\" (cubos e paralelepípedos), \"2D\" (placas espessas, placas finas e placas alongadas) e \"1D\" (placas alongadas e ripas) por meio da variação da composição do meio reacional inicial. Reações conduzidas em meios com pH característico de suspensões de gibsita em água (pH alcalino) resultaram em cristais com morfologia \"3D\" ou \"2D espessa\", enquanto reações conduzidas em meio acidificado (pH = 2,0) resultaram em cristais com morfologia \"2D\". Reações conduzidas em meios acidificados contendo íon acetato levaram a cristais com morfologia \"2D fina e alongada\" ou morfologia \"1D\", dependendo da relação molar [Al : acetato] inicial de íon acetato (morfologia \"1D\" necessita de uma relação molar de no mínimo 1mol Al : 1mol acetato). Os cristais com morfologia \"1D\" e \"2D fina\" apresentaram espessuras nanométricas. A evolução térmica dos cristais de boemita produzidos foi estudada após aquecimentos entre 200ºC e 1200ºC. Todas as boemitas seguiram as transformações térmicas da chamada \"série ?\" , independentemente da sua morfologia, ou seja: boemita -> alumina-? -> alumina-? / alumina-? -> alumina-?. A temperatura de transformação da boemita em alumina-? é afetada pela morfologia dos cristais, ocorrendo em temperaturas mais baixas nos materiais com cristais de espessura nanométrica (morfologias \"1D\" e \"2D fina\"). Alumina-? com diferentes morfologias e diferentes áreas específicas (determinadas pelo método BET aplicado a isotermas de adsorção de nitrogênio gasoso a 77K) foram obtidas: 136 m2/g para alumina-? \"1D\"; 73,4 m2/g para alumina-? \"2D fina e alongada\"; 40,3 m2/g para alumina-? \"3D\". Foi possível, portanto, obter aluminas de transição potencialmente interessantes para aplicações industriais dadas as elevadas áreas específicas observadas. / Aluminum oxides and hydroxides have been the subject of studies in Laboratório de Matérias-Primas Particuladas Prof. Pérsio de Souza Santos (LPSS) in the last six decades. Several synthesis routes for mono- and tri-hydroxides were investigated as well as the thermal processing of these materials into transition aluminas and alpha-alumina. More recently, the synthesis of boehmite from the hydrothermal treatment of gibbsite has been the main object of studies in LPSS. In this Thesis, the hydrothermal synthesis of boehmite from a commercial Bayer gibbsite was studied. The crystals produced were characterized by X-ray diffraction (XRD), thermal analysis (TGA and DTA) and scanning electron microscopy (SEM). Different boehmite crystal morphologies were obtained - crystals \"3D\" (cubes and parallelepipeds), \"2D\" (thick plates, thin and elongated plates) and \"1D\" (elongated plates and strips) by varying the composition the initial reaction medium. Reactions conducted in media with characteristic pH of gibbsite suspension in water (alkaline pH) resulted in crystals with morphologies \"3D\" or \"thick 2D\" while reactions carried out in acidic medium (pH = 2.0) resulted in crystals with morphology \"2D\". Reactions carried out in acidic media containing acetate ion led to crystals with a \"thin and elongated 2D\" morphology or \"1D\" morphology, depending on the pristine [Al: acetate]. molar ratio (\"1D\" morphology requires a pristine molar ratio of at least 1mol Al: 1mol acetate). Crystals with \"1D\" or \"2D thin\" morphologies presented nanometric thickness. The thermal evolution of boehmite crystals produced was studied after heating between 200oC and 1200oC. All boehmites following thermal \"?-series\" transformation, regardless of their morphology, that is: boehmite -> ?-alumina -> ?-alumina /?-alumina -> ?-alumina. The transformation temperature of boehmite into ?-alumina is affected by crystal morphology, occurring at lower temperatures in the materials with nanometer thick crystals (\"1D\" and \"2D thin\" morphologies). ?-alumina with different morphologies and different specific surface areas (determined by BET method applied to adsorption isotherms of gaseous nitrogen at 77K) were obtained: 136 m2/g for ?-alumina \"1D\"; 73.4 m2/g for ?-alumina \"thin and elongated 2D\"; 40.3 m2/g for ?-alumina \"3D\". It was therefore possible to obtain transition aluminas potentially interesting for industrial applications given the high specific surface areas observed.

M. Tech. Polymer Technology. / This study was undertaken to investigate the effect of the addition of boehmite alumina (AlO(OH)) nanoparticles in polypropylene grafted maleic anhydride (PP-g-MA) compatibilized polypropylene (PP)/polyamide 12 (PA12) blend.