Teses / dissertações sobre o tema "Fibre de carbonate de calcium"
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Longkaew, Khansinee. "Preparation of calcium carbonate particles for application in natural rubber composites". Electronic Thesis or Diss., Le Mans, 2024. https://cyberdoc-int.univ-lemans.fr/Theses/2024/2024LEMA1003.pdf.
Texto completo da fonteThis research aims to synthesize different types and shapes of calcium carbonate (CaCO3) particles at a submicrometric and nanoscale, and investigate their applications as reinforcing fillers for natural rubber (NR) composites. The study was therefore divided into two parts. Firstly, the preparation procedure of CaCO3 particles was based on the solution precipitation method between carbonate ions and calcium ions. The second part focused on investigating the mechanical properties of NR/CaCO3 composites. The first part started with the precipitation of (NH4)2CO3 and CaCl2 dissolved in 50% by weight of sucrose as the aqueous medium. This condition resulted in spherical CaCO3 with particle size of 0.42±0.14 µm with an aspect ratio of about one. When the precipitation reaction occurred in the presence of olive soap, the surface property of the CaCO3 was changed from hydrophilic (water contact angle of 28±2o) to superhydrophobic powders (water contact angle of 163±2o). The typical polymorphic phases of CaCO3 were characterized. The results revealed that both untreated and treated spherical CaCO3 were about 99% of the vaterite polymorph. In the precipitation process using Na2CO3 and CaCl2 aqueous solutions performed at 80±1C, bundle-liked CaCO3 was obtained with an aspect ratio in the range of 8–9. The superhydrophobic bundle-liked CaCO3 was also successfully synthesized by soap treatment. The water contact angle of untreated and treated bundle-liked are 29±2o, and 167±2o, respectively. Furthermore, the spherical CaCO3 dispersed in water at 80C resulted in the fiber-shaped CaCO3 nanoparticles which were achieved via the polymorph transformation from spherical vaterite to long nano-wired aragonite with the highest aspect ratio of 156.9. The untreated fiber CaCO3 was hydrophilic with a water contact angle of 31±1o, while the treated fiber CaCO3 with soap resulted in 165±5o of water contact angle, hence it was superhydrophobic similar to other synthesized CaCO3 polymorphs. The XRD revealed that the untreated and treated bundle-liked and fiber-shaped CaCO3 contained the majority of aragonite followed by vaterite and calcite polymorphs. The second part was carried out to incorporate the prepared CaCO3 (0,5,10,20,40,60 phr) in NR latex. It was found that the CaCO3 polymorphs were stable in the NR latex medium. The mechanical properties of NR/CaCO3 included tensile strength, elongation at break, tear strength, and hardness Shore A. It was found that the tensile strength of NR/CaCO3 composites increased when CaCO3 loading was increased. The tensile strength of NR improved from 22.68±2.22 MPa of neat NR up to 23.94±0.97 MPa when untreated spherical CaCO3 powders (20 phr) were added, and to 25.28±0.80 MPa of treated spherical CaCO3 (20 phr) filled NR. The maximum tensile strength of NR/untreated bundle-liked CaCO3 was 30.59±3.50 MPa at 40 phr of loading while 31.51±1.02 MPa of NR/treated bundle-liked CaCO3 at filler loading 20 phr was obtained. The treated CaCO3-filled NR vulcanizates gave higher tensile strength than the untreated ones. This was caused by better compatibility of filler dispersion between the hydrophobicity of treated CaCO3 and hydrophobic property of NR. As a result, it was found that the NR filled with untreated fiber CaCO3 particle provided the highest tensile strength of 31.66±1.80 MPa at 10 phr of filler loading, over other types of CaCO3. The nanoparticle, large surface area, and high aspect ratio of fiber/ long nano wired of CaCO3 enhanced the interfacial adhesion between CaCO3 and NR matrix which could transfer stress from rubber to filler effectively during stretching. This resulted in the reinforcing efficacy of the fiber CaCO3. In summaroze, the prepared CaCO3 powders have the potential to broaden their application not only as diluents or additives but also as reinforcing agents
Reygrobellet, Jean-Noël. "Recyclage de composites fibres de verre-polyester insaturé-carbonate de calcium par réincorporation dans des matrices thermoplastiques". Montpellier 2, 2000. http://www.theses.fr/2000MON20038.
Texto completo da fonteSafa, Ali Ibrahim 1953. "Catalytic Calcination of Calcium Carbonate". Thesis, North Texas State University, 1985. https://digital.library.unt.edu/ark:/67531/metadc330965/.
Texto completo da fonteXu, Yaling Pelton Robert H. "Calcium carbonate adhesion in paper /". *McMaster only, 2005.
Encontre o texto completo da fonteLoste, Madoz Eva. "Morphological control of calcium carbonate". Thesis, Queen Mary, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398861.
Texto completo da fonteDaly, P. J. "Dissolution kinetics of calcium carbonate". Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372693.
Texto completo da fontePicard, Quentin. "Biomatériaux hybrides : tissu de fibres de carbone / phosphates de calcium : synthèse, caractérisation et biocompatibilité". Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2073/document.
Texto completo da fonteThis work is focused on the synthesis of a novel hybrid biomaterial made of carbon fibers cloth (CFC)/ calcium phosphates (CaP) using the sono-electrochemical technique and the study of the influence of experimental parameters on the chemical composition, microtexture and structure of CaP deposits and on in vitro biocompatibility. Current density is shown to be a crucial parameter. Specifically, at high current densities ((≥ 100 mA/g), the fast water electrolysis rate leads to a needle-like deposit consisting in a major phase of carbonated calcium deficient hydroxyapatite (CaD-HAP) mixed with a calcium carbonate phase. At low current densities (≤ 50 mA/g), the slow water electrolysis rate generates a plate-like carbonated CaD-HAP phase, coming from the in situ hydrolysis of a former octacalcium phosphate phase. Whatever the experimental conditions, particles of the deposits consists in a carbonated CaD-HAP core showing an ordered structure, surrounded by a hydrated and disordered carbonated CaD-HAP surface layer which results of the formation of oversaturated domains during CaP precipitation. Sono-electrodeposition is shown to be a versatile process able to control the nature of CaP phases. Especially, at low current density a biomimetic CaP deposit is obtained, similar to the mineral part of bones produced during natural osteogenesis. In vitro biologic tests using primary human osteoblasts showed that the nano-porosity and hydrophilicity of the carbon fibers do not affect the biocompatibility and that fiber precursor, sizing and lobe shaped fibers seems to favor adhesion and proliferation of human cells
Lam, Siu Kai Raymond. "Calcium carbonate deposition in synthetic systems". Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492548.
Texto completo da fonteD'Souza, Sharon Marie. "Molecular imprinting of calcium carbonate crystals". Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428182.
Texto completo da fonteWang, Q. "A computational study of calcium carbonate". Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1333995/.
Texto completo da fonteMacAdam, Jitka. "Calcium carbonate scale formation and control". Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/10544.
Texto completo da fonteFinney, Aaron R. "Nucleation and dehydration of calcium carbonate". Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/66884/.
Texto completo da fonteMitchell, Colin Raymond. "Numerical Simulation of Calcium Carbonate Formation". University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1294360826.
Texto completo da fonteOlivier, Florian. "Elaboration, caractérisation, dopages et évaluations in vitro et in vivo de matériaux hybrides : Tissus de fibres de carbone / Phosphates de calcium". Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2052/document.
Texto completo da fonteOptimization of the synthesis of calcium phosphates (CaP) on carbon fiber cloths (TFC) was performed in using sono-electrodeposition process in order to obtain uniform coatings. The electrochemical potential applied and the electrolyte temperature during the synthesis were determined as being key parameters. For a constant potential of -1 V at 70 ° C, a controlled water electrolysis regime results in the deposit of plate-like calcium-deficient apatite (CDA). This plate-like particles (from a few tens to hundreds of nm in length) consist in an ordered structure of carbonated CDA in their core and in a disordered structure in the hydrated surface, a typical organization of biomimetic apatites. The hybrid material was doped with strontium, resulting in a carbonated CDA coating where the Ca²+ ions are controllably substituted by Sr²+ ions, leading to new properties for a bone regeneration application. This work has also shown the possibility of selectively adsorb targeted active molecules (tetracycline, naproxen, aspirin) in each component of the hybrid material. The desorption curves revealed two modes of release depending on the active molecule.A biological evaluation of the different hybrid materials was carried out. The in vitro study investigated the viability and proliferation of human osteoblasts at the surface of hybrid materials, demonstrating their biocompatibility. The interest of a doping (Sr²+, aspirin and naproxen) on osteoblast activity was demonstrated. An in vivo pilot experiment was conducted, through the creation of a bone defect in rat thighbones to study the influence of TFC/CaP biomaterials on the quantitative and qualitative evolutions of bone regeneration
Ahsan, T. "Surface characterization of the precipitated calcium carbonate". Thesis, Brunel University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374851.
Texto completo da fonteHetherington, Nicola B. J. "Synthetic Routes to Multiscale Calcium Carbonate Architectures". Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520669.
Texto completo da fonteBabou, Kammoe Romuald Brice. "Synthèse de nanoparticules de carbonate de calcium". Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27760/27760.pdf.
Texto completo da fonteBrown, Christopher A. "Aspects of the calcium carbonate-water interface". Thesis, University of Oxford, 1992. http://ora.ox.ac.uk/objects/uuid:0d9222b6-2d2a-4f3d-a0f9-61f91433dd02.
Texto completo da fonteDobson, Phillip Stephen. "Calcium carbonate crystallisation at the microscopic level". Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252524.
Texto completo da fontePownall, P. G. "The surface electrical properties of calcium carbonate". Thesis, University of Bristol, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379592.
Texto completo da fonteHooper, Rebecca Louise. "Calcium carbonate fillers in rosin-sized papers". Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/32797.
Texto completo da fonteOndo, Ndjimbi Lilian Urlain. "Production of calcium carbonate from phosphogypsum wastes". Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/79298.
Texto completo da fonteDissertation (MSc)--University of Pretoria, 2014.
Chemistry
MSc
Unrestricted
Venturini, Chiara. "On-surface coupling reactions on calcium carbonate". Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30158/document.
Texto completo da fonteCovalent coupling on metallic surfaces in UHV (Ultra High Vacuum) conditions is a new method for preparing molecular structures otherwise impossible to achieve in solution (graphene nanoribbons, 2D polymers for instance). The major challenge is now to extend these reactions from metallic to insulating surfaces, for future applications as, for instance, in molecular electronics. In particular, the coupling reaction of benzoic acid derivatives, grafted on calcite via carboxylic groups, has been demonstrated for the first time in UHV conditions. In the first part of this work, we synthesized precursor molecules for specific reactions (homocoupling of ethynes, photopolymerization, polycondensation and Ullmann reaction) on calcium carbonate in UHV conditions. In the second part of this work we extended this investigation up to the macroscale level (semi-preparative) by grafting molecules on calcium carbonate microparticles, followed by reaction activation and finally by dissolution of the substrate in order to recover the coupling products. The calcium carbonate microparticles were prepared by grinding commercial product or by spray pyrolysis and were fully characterized by FTIR, TG/DTG, XRD, SEM and BET techniques. Then, after grafting of organic reactant, the reactions were activated with two different solvent-free methods: by grinding in a planetary milling machine or by heating the samples in a furnace under vacuum. Whereas in UHV conditions, 4-iodobenzoic acid affords biphenyldicarboxylic acid, mechanochemical condition gives benzoic acid and thermal activation the dibenzoic acid ether
Lin, Yong. "Toughening mechanism of polypropylene/calcium carbonate nanocomposites /". View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CBME%202009%20LIN.
Texto completo da fonteHarris, Derek Daniel. "A Kinetic Study of Aqueous Calcium Carbonate". BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3845.
Texto completo da fonteJafari, Abbas. "The Effect of Citric Acid on Amorphous Calcium Carbonate, Mesoporous Magnesium Carbonate and Calcium Magnesium Composite : A brief study". Thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-435989.
Texto completo da fontePresentationen genomfördes på distans.
Gagnon, Gerard R. "The Colloidal Properties and Rheological Behavior of Precipitated Calcium Carbonate Suspensions Dispersed with Sodium Polyacrylate". Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/GagnonG2008.pdf.
Texto completo da fonteEngland, Jennifer Katherine. "Calcium carbonate biomineralisation in disparate systems : common mechanisms?" Thesis, University of Glasgow, 2005. http://theses.gla.ac.uk/4024/.
Texto completo da fonteBindley, Lucy Ann. "Calcium carbonate growth and dissolution to the nanoscale". Thesis, University of Warwick, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425538.
Texto completo da fonteRajam, S. "Controlled crystallization of calcium carbonate under Langmuir monolayers". Thesis, University of Bath, 1990. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760610.
Texto completo da fonteAl, Qabany Ahmed Abdul Aziz. "Microbial carbonate precipitation in soils". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609845.
Texto completo da fonteBennani-Ziatni, Mounia. "Etude du système phosphate de calcium, carbonate de calcium en milieu eau-éthanol". Toulouse, INPT, 1986. http://www.theses.fr/1986INPT004G.
Texto completo da fonteBennani-Ziatni, Mounia. "Etude du système phosphate de calcium carbonate de calcium en milieu eau-éthanol". Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375959373.
Texto completo da fonteBerry, Jeffrey Nicholas. "Sulfate in foraminiferal calcium carbonate : investigating a potential proxy for sea water carbonate ion concentration". Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/53536.
Texto completo da fonteIncludes bibliographical references (leaves 82-85).
The sulfur content of planktonic and benthic foraminifera was measured in specimens recovered from deep-sea sediment cores and individuals grown in culture. A new method for measuring sulfur in foraminiferal calcium carbonate was developed, employing a high-resolution inductively coupled plasma-mass spectrometer. The sulfur measurements, expressed as sulfur-to-calcium (S/Ca) ratios in the foraminiferal shells, ranged from 0.26 to 6.0 mmol/mol. Most analyses fell in the range of 0.7 to 2.5 mmol/mol. Culturing experiments were conducted in the planktonic foraminifer G. sacculifer to test the hypothesis that S/Ca ratios in the foraminifer are inversely proportional to the carbonate ion concentration in the seawater in which they grow, and hence proportional to the pH of the seawater. The slope of the relationship between cultured G. sacculifer S/Ca and the pH of the seawater medium was -1.92 mmol mol-1/pH unit with a least squares linear correlation coefficient, r2=0.927. The S/Ca ratios of planktonic and benthic foraminifera from Holocene and last glacial period sediments were measured in an effort to use the established relationship of S/Ca and pH to calculate the ocean pH gradient between Holocene and glacial time. The results indicate the pH of global ocean deepwater was 0.10 to 0.15 pH units higher during glacial time than today. Smaller pH gradients were seen for some cores which may have been caused by circulation-induced water mass changes. Surface ocean changes in pH over the Holocene-glacial interval seem to vary from region to region, with up to an 0.2 pH unit increase at the Sierra Leone Rise in glacial time. Benthic foraminifera from coretops in the thermocline of the Little Bahama Bank were analyzed for S/Ca to examine the effects of hydrographic variables on S/Ca. The relationship of S/Ca to pH and [CO3=] has a positive slope, at odds with the expected negative slope from the previous results. The S/Ca results do correlate well with salinity, suggesting that salinity or other hydrographic parameters may also influence foraminiferal S/Ca ratios.
by Jeffrey Nicholas Berry.
M.S.
Stephens, Christopher James. "On the transformation of amorphous calcium carbonate into calcite". Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534898.
Texto completo da fonteBello, Omoregbe. "Calcium carbonate scale deposition kinetics on stainless steel surfaces". Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17647/.
Texto completo da fonteDoyat, Sylvie. "Mélanges polypropylène-carbonate de calcium : extrusion réactive et rhéologie". Lyon 1, 1998. http://www.theses.fr/1998LYO19009.
Texto completo da fonteLEVREL, LE METAYER GAELE. "Microbiogeologie du carbonate de calcium : applications industrielles, implications geologiques". Nantes, 1996. http://www.theses.fr/1996NANT2115.
Texto completo da fonteAlipour, A. "Nanoclay as Substitute of Calcium Carbonate in NBR Compounds". Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35036.
Texto completo da fonteHuang, Jin-Mo. "Model Development for the Catalytic Calcination of Calcium Carbonate". Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc331193/.
Texto completo da fonteKawano, Jun. "Molecular Dynamics Simulation on the Polymorphism of Calcium Carbonate". 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/149085.
Texto completo da fontePorter, Hannah Elizabeth. "Stabilisation of Geomaterials using Microbially Induced Calcium Carbonate Precipitation". Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/75981.
Texto completo da fonteSchnebelen, Mathilde. "Étude de l'agglomération lors de la précipitation de carbonate de calcium par un procédé de carbonatation d'une suspension d'hydroxyde de calcium". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0131/document.
Texto completo da fontePrecipitated calcium carbonate (PCC) is a mineral additive of various applications in paints, pharmacy, cosmetics, etc. It can be industrially synthesized through several ways but the most common one is the carbonation route. It consists in bubbling carbon dioxide in a suspension of calcium hydroxide to get particles of PCC. However, the challenge related to the synthesis and the use of this precipitate is the control of the agglomeration of the monoparticles. Indeed, they are agglomerated in micrometric "loose" structures. This agglomeration has consequences on the run of the process and the end use properties of the final product. Thus, the aim of this work is to understand the mechanisms of this phenomenon, to determine its kinetics and to study the impact of different process parameters under complex industrial conditions. The method to determine the agglomeration kernel is based on the resolution of a population balance using the moment approach. Provided that the kinetic rates of nucleation and growth are known, the agglomeration kernel can be obtained from a mathematical treatment of the experimental particle size distributions. Thanks to an agglomeration kernel model including the crystal growth, it is possible to determine the value of the agglomeration constant. Finally, by varying different process parameters, it also appears that the agglomeration constant increases with temperature whereas an optimum is observed for the shear rate. Regarding to this fact, we can also propose an expression of the agglomeration constant as a function of the shear rate, which can be used to control the agglomeration in the industrial reactor
Farrell, Vanessa A. "Calcium: A Simple Guide". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2011. http://hdl.handle.net/10150/146446.
Texto completo da fonteOriginally published: 2002
It is important to know how much calcium you need to consume each day as more than 2500 mg of calcium each day can be harmful. Calcium should be obtained from foods and beverages first, then from supplements if necessary. Taking more than 500 mg of calcium at one time should be avoided. If you choose to take a calcium supplement, calcium citrate or calcium carbonate should be chosen.
Wang, Yuan School of Chemical Engineering & Industrial Chemistry UNSW. "Composite fouling of calcium sulfate and calcium carbonate in a dynamic seawater reverse osmosis unit". Awarded by:University of New South Wales. School of Chemical Engineering and Industrial Chemistry, 2005. http://handle.unsw.edu.au/1959.4/26007.
Texto completo da fonteCantaert, Bram. "Controlled crystallisation of calcium phosphate and calcium carbonate via bio-inspired approaches : additives and confinement". Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/4683/.
Texto completo da fonteMadrick, Tracy L. "The availability of calcium from various commercial sources of calcium carbonate and fortified food products". Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/53228.
Texto completo da fonteMaster of Science
Patel, Vishal M. "Synthesis of calcium carbonate coated emulsion droplets for drug detoxification". [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE1001175.
Texto completo da fonteBecker, Alexander. "Structural characterisation of biominerals and biomimetic crytallisation of calcium carbonate". [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=97572861X.
Texto completo da fonteGupta, Ritika. "Synthesis of Precipitated Calcium Carbonate Nanoparticles Using Modified Emulsion Membranes". Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5158.
Texto completo da fonte