Spelling suggestions: "subject:"kaolinite""
161 |
Schätze im Geopark: Kaolin – das weiße GoldHeß, Viola, Heidenfelder, Wolfram 12 November 2019 (has links)
No description available.
|
162 |
Geotope - Einblicke in die ErdgeschichteGeißler, Marion, Hartmann, Anja, Heidenfelder, Wolfram, Witzke, Tim 11 November 2019 (has links)
Naturschutz ist inzwischen tief in unserem Denken und Handeln angekommen. Aber
noch immer wird dabei zu allererst an den Schutz von Tieren und Pflanzen gedacht, gefolgt vom Schutz des oberirdischen und unterirdischen Wassers. Das ist verständlich, hat doch diese Art des Naturschutzes lange zurückliegende Wurzeln.
|
163 |
Weg zum Kaolin: Georoute 2: Unterwegs im Geopark Porphyrland - Stadt Mügeln05 July 2022 (has links)
Die Stationen des Rundwegs machen mit der geologischen
Entstehung des Rohstoff s Kaolin, den
Lagerstätten im „Land der weißen Erde“ um Mügeln
und dem Kaolinabbau vertraut. Kaolin dient
insbesondere als Grundstoff zur Herstellung von
Porzellan, Steingut, Sanitär- und Elektrokeramik.
Johann Friedrich Böttger nutzte den Kaolin aus
der Region um Colditz bei der Erfindung des ersten
europäischen Hartporzellans, dem „weißen Gold“ Sachsens.
|
164 |
Keramik-Kunst-Routen: Georouten 5/6: Unterwegs im Geopark Porphyrland - Stadt Colditz05 July 2022 (has links)
Die Stadt Colditz besitzt neben ihrem berühmten Schloss
eine lange Tradition in der Herstellung keramischer
Waren. Mit „Colditzer weißer Erde“ aus einer Kaolingrube
am nordöstlichen Ortsrand erfanden Johann Friedrich
Böttger und Ehrentraut Walther von Tschirnhaus im
Auftrag von Kurfürst August dem Starken 1708 das erste
europäische Hartporzellan, das als Meißener Porzellan
weltberühmt wurde. Es folgte eine bedeutende, heute
aber vollständig verlorene Keramikindustrie. Auf den
Spuren der Colditzer Keramikgeschichte führen Keramik-
Kunst-Spaziergang und -Radroute zu den wichtigsten
Standorten einstiger Firmen. Kleine Kunstobjekte am
Weg erinnern an ihre zum Teil weltweit begehrten Produkte
und die verschiedenen Produktionstechniken.
|
165 |
Разработка состава массы для производства глазурованного керамического гранита : магистерская диссертация / Development of the composition of the mass for the production of glazed ceramic graniteКуташева, С. С., Kutasheva, S. S. January 2019 (has links)
Целью магистерской диссертации является разработка состава массы для производства глазурованного керамического гранита. В работе исследованы свойства сырьевых материалов. Определены технологические параметры производства и разработана технология производства для производства глазурованного керамического гранита. / The aim of the master's thesis is to develop the composition of the mass for the glazed ceramic granite production. The paper investigated the properties of raw materials. The technological parameters of production are determined and the production technology for the production of glazed ceramic granite is developed.
|
166 |
Paleo-environmental conditions and tectonic settings of cretaceous-tertiary kaolins in the Eastern Dahomey and Niger Delta Basins in Nigeria.Oyebanjo, Olaonipekun Moses 18 May 2018 (has links)
PhDENV (Geology) / Department of Mining and Environmental Geology / The Cretaceous period marked the breaking up of Gondwana, giving rise to the
separation of the African and South American continents with the subsequent emergence
of the South Atlantic Ocean. Most correlation studies between the two continents with
respect to paleoenvironmental conditions and tectonic settings during the Cretaceous-
Tertiary periods have been concentrated more on the use of flora and fauna as indicators
with less application of kaolinite as paleoenviromental proxies, hence, this study.
The research involved the evaluation of paleoenvironmental conditions and tectonic
settings of four (4) selected Cretaceous-Tertiary kaolin deposits with two (2) each from
the Eastern Dahomey (Eruku and Lakiri) and Niger Delta (Awo-Omama and Ubulu-Uku)
Basins in Nigeria. Representative kaolin samples collected from the selected deposits
were analysed for physico-chemical, mineralogical, geochemical, isotopic, and
geochronological data. The geochemical data obtained by x-ray fluorescence (XRF)
spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LAICPMS)
were used in unraveling the provenance and tectonic settings of the kaolins. The
kaolinite stable isotopic data for oxygen and hydrogen determined using a Finnigan Delta
XP Mass Spectrometer were used to assess the paleoenvironmental and paleoclimatic
conditions under which the kaolins were formed. The detrital zircon geochronological data
acquired by laser ablation – single collector – magnetic sectorfield – inductively coupled
plasma – mass spectrometry (LA-SFICP-MS) as well as kaolinite stable isotopic data
were employed in constraining the probable timing of kaolinisation. The industrial
applications of the kaolins were assessed based on the physico-chemical (Colour, particle
size distribution (PSD), pH, electrical conductivity, and Atterberg limits), mineralogical,
and geochemical data. The mineralogical data were obtained through x-ray diffractometry
(XRD), Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric analysis and
differential scanning calorimetry, and scanning electron microscopy (SEM). Correlative
studies between selected Cretaceous African and South American kaolins were
conducted.
The results showed that the dominant colour in the studied kaolins was pale red (39 %)
followed by pinkish and light grey (35 %) as well as reddish yellow, light pink, light brown,
vii
reddish brown, and pinkish white. The pH and EC values generally ranged from 4.27 to
5.29 and 0.2 to 13.1 μS/cm, respectively. The kaolins predominantly have clay to sandy
clay textures with plasticity indices between 10 and 22 wt %.
Bulk mineralogical quantitative results indicated that the Cretaceous kaolins have
kaolinite, quartz, and muscovite present in that decreasing order with anatase, goethite,
and hematite in traces whereas Tertiary kaolins have kaolinite and quartz present in that
decreasing order with anatase and goethite in traces. In the silt fractions, kaolinite and
quartz were the dominant mineral constituents, whereas in the clay fractions, the
dominant clay mineral was kaolinite accounting for 69 to 99 wt % with the non-clay
minerals like quartz, anatase, hematite and goethite accounting for percentages between
1 to 28 wt % in the Cretaceous – Tertiary kaolins. Morphologically, the studied kaolins
were characterised by pseudohexagonal stacks to books and thin platy kaolinite particles
with moderate structural order.
The chemical compositions of the Cretaceous-Tertiary kaolin deposits were identical to
hydrated alumino-silicates based on the dominance of SiO2, Al2O3 and LOI. The chemical
index of alteration (CIA) and chemical index of weathering (CIW) values varied between
96.98 to 99.39 % and 98.95 to 99.89 %, respectively. The clay fractions were enriched in
Cr, Nb, Sc, Th, U, V, Zr, and LREE and depleted in Ba, Co, Rb, Sr, and HREE,
respectively, relative to the average Upper Continental Crust (UCC). The Th/Sc, La/Sc,
Th/Cr, and Eu/Eu* ratios were within the range of sediments derived from felsic rocks.
The TiO2 versus Al2O3 and La-Th-Sc plots indicated source rocks with granitic –
granodioritic - gabbroic compositions. Geochemical discrimination plots showed that the
Cretaceous and Tertiary kaolins were deposited in passive margin tectonic settings.
The stable isotopic results indicated that the values of the Cretaceous kaolins ranged
from – 47 to – 57 ‰ and 19.1 to 19.8 ‰, respectively, with paleotemperatures between
29.0 and 32.2 ˚C, whereas the δD and δ18O corresponding values for the Tertiary kaolins
ranged from – 54 to – 66 ‰ and 20 to 21.5 ‰, respectively, with paleotemperatures
between 17.0 and 23.9 ˚C.
viii
The U-Pb dating of the detrital zircons showed that the Cretaceous - Tertiary kaolins have
inputs from rocks of Eburnean (2500 – 2000 Ma) and Pan African (750 – 450 Ma) ages.
The age of maximum deposition determined from the least to statistically robust approach
corresponds to the Ediacaran Period (645 – 541 Ma) of the Neoproterozoic Era (1000 –
541 Ma).
The Cretaceous – Tertiary kaolins were formed under intense anoxic chemical
paleoweathering conditions of predominantly felsic rocks in addition to contributions from
intermediate and mafic rocks in passive margin tectonic settings. The Cretaceous kaolins
were formed under warmer conditions relative to the Tertiary kaolins. The West African
Massif rocks were the main sediment sources for the Cretaceous kaolins, whereas both
the West African and Northern Nigerian Massif rocks were the major sediment sources
for the Tertiary kaolins. The most probable timing of kaolinisation for the Cretaceous –
Tertiary kaolins occurred between the Ediacaran (645 – 541 Ma) and Early Cretaceous
Periods for the Cretaceous kaolins and between the Ediacaran Period (645 – 541 Ma)
and Oligo – Miocene age for the Tertiary kaolins. The Nigerian and Brazilian Cretaceous
kaolins formed under similar warm tropical paleoclimate. The study corroborated the
occurrence of the Eburnean (Transamazonian) and Pan African (Brasiliano) orogenic
events across the African and South American continents. Beneficiation of the
Cretaceous – Tertiary kaolins will allow large scale industrial applications in paper
coating, ceramics, pharmaceutical, and cosmetics industries.
The major contributions from this study have been: the better understanding of the past
environmental conditions and tectonic settings, the dating of the possible timing of
kaolinisation, and improvement on the potential industrial applications of the Cretaceous
– Tertiary kaolins. / NRF
|
167 |
Síntese e caracterização de macromoléculas do tipo Poli(Ácido carboxílico)-Poli(Eter-poliol) com propriedades termoplásticas e termorrígidas e avaliação de propriedades mecânicas cerâmicos à base de caulim. / Synthesis and characterization of macromolecules of the type of poly (carboxylic acid)-poly(ether polyol) with thermoplastic and thermoset properties and evaluation of mechanical properties of ceramics materials based on kaolin.Rodrigues, José Carlos 27 August 2009 (has links)
Este trabalho apresenta o estudo de um sistema polimérico bi-componente formado por Poli(Ácido carboxílico)-Poli(Eter-poliol), constituído primariamente de um polímero acrílico polimerizado pelo processo de polimerização em solução aquosa por mecanismo de radicais livres ao qual foi adicionado seqüencialmente, um Poli(Eter-poliol), ambos de baixo peso molecular médio. Tal sistema tem por finalidade atuar como dispersante-ligante em sistema cerâmico à base de caulim CADAM, uma vez que este sistema apresenta propriedades termoplásticas e termorrígidas a diferentes temperaturas. Foram sintetizados 03 protótipos de um sistema polimérico e o critério para escolha teve como base o pH do sistema em sentido generalizado, isto é, compreendendo as diversas fases de preparação dos polímeros e sua aplicação final. É do conhecimento comum que a reação de esterificação entre grupos COOHOH requer catálise ácida para ocorrer, o qual usualmente é realizada em pH abaixo de 4 e, neste ensaio, este pH ácido é devido à presença de ácido para-toluenosulfônico, que atua como catalisador de esterificação. Em tal intervalo de pH, em virtude do ponto isoelétrico do caulim ser comumentemente abaixo de 4, a estabilização da dispersão de caulim por repulsão eletrostática utilizando polímeros sintéticos é improvável de ocorrer, razão pela qual buscou-se mecanismos alternativos para obtenção de uma tal estabilização, entre os quais o mecanismo estérico surge como opção. O sistema polimérico do presente estudo apresenta-se na forma de uma solução aquosa sendo, de fato, uma mistura homogênea de um copolímero de ácido acrílico, N- metiloacrilamida e metacrilato de metoxipolietileno glicol e um poli(eter-poliol). O poli(eter-poliol) e N-metilolacrilamida presentes no sistema polimérico são principais fontes de grupo hidroxila para reação de poliesterificação e formação de ligações cruzadas à temperatura de 150 a 200 °C. No estado termoplástico o sistema polimérico produzido pela mistura poli(ácido carboxílico)-poli(eter-poliol) pode ser utilizado como dispersante de argilas com especial fóco sobre caulim como tratado neste trabalho. A propriedade dispersante pode ser atribuida à presença de grupos carboxílicos e metoxipolietilenoglicol aleatoriamente distribuídos ao longo da cadeia polimérica e, também, ao baixo peso molecular médio. A temperaturas entre 150 a 200 °C, o polímero é reticulado (crosslinked) por reação de poliesterificação, catalisada por ácido, entre grupos carboxila e grupos hidroxila, sendo as hidroxilas provenientes tanto de poliol como de N-metilolacrilamida (NMAM). Assim, do ponto de vista térmico comporta-se como termorrígido, sendo nesta condição insolúvel em água e adequado atuar como ligante na manufatura de materiais cerâmicos. Medidas de mobilidade eletroforética e viscosidade são aplicadas à caracterização de caulim e do sistema polimérico a fim de avaliar a potencialidade de aplicação como dispersante desta argila. Também, as transições dos estados termoplásticos para termorrigidos foram determinadas por análise termogravimétrica (TG) e análise dinâmico mecânica (DMA) nos polímeros isoladamente e depois com medidas de resistência mecânica do sistema caulim/polímero. O sistema apresentou comportamento dispersante em água e ligante após cura. Um sistema polimérico assim sintetizado foi propriamente curado por calor tornando- se, na forma termorrígida, um ligante para peças cerâmicas com propriedades mecânicas de alto desempenho, como resistência a flexão no estado cru (green strenght). / This work presents the study of a polymeric bi-component system made from Poly(carboxylic acid)-Poly(ether-polyol) primarily constituted of an acrylic acid polymerized through the process of aqueous solution polymerization by free radical mechanism, to which a poly(ether-polyol) has been sequentially added, both of them of low average molecular weight. Such a system has the aim to act as dispersing-binding balance on CADAM kaolin targeting to evaluate the applicability potential or the preparation of ceramic bodies as this polymeric system presents thermoplastic and thermosetting properties at different temperatures. Were made the synthesis of 03 polymeric system prototypes which criteria for choice was based on pH of the system at whole sense, that is, regarding the several steps for polymers preparation and its final application. It is knowledge that esterification reaction between COOH-OH groups requires acid catalyst to occur, which usually is done at pH below 4 and, in this work this pH is due to p-toluene sulfonic acid that act as esterification catalyst. In this range of pH, due to the isoeletric point of kaolin to be below 4 the electrostatic stabilization of dispersion is unlikely to occur, from which reason was looked for an alternative mechanism to achieve the dispersion stabilization, among them the steric mechanism arises an option. The polymeric system of this study is the form of an aqueous solution, which actually is a homogeneous blend of a copolymer of acrylic acid, N-Methylolacrylamide Methoxypolyethyleneglycol Methacrylate (MPEGMA) and Poly(ether-polyol). The Poly(etherpolyol) and the N-Methylolacrylamide presents at the polymeric system are the main sources of hydroxyl groups to enhance the polyesterification reaction for further crosslinking at temperatures from 160 to 200 °C. At the thermoplastic state the polymeric system made by Poly(carboxilic acid)poly(ether-polyol) macromolecules may be used as clay dispersant focusing on kaolin for this work. The dispersant property may be attributed to the carboxylic and methoxypolyethyleneglycol group randomly distributed along the polymeric chain backbone and, also to the low average molecular weight. At temperatures between 150 to 200 °C, the polymer is crosslinked by polyesterification reaction catalized by acid between carboxyl groups and hydroxyl groups, in such way that hydroxyls groups comes both from the polyol base polymer and NMethylolacrylamide (NMAM) present at first polymer backbone. Thus, through a thermal standpoint it behaves as thermoset being that, under this condition, water insoluble and adequate to act as binder for manufacturing of ceramic materials. Electrophoretic mobility and viscosity measurements were applied for the characterization of kaolin and the polymeric system targeting to the evaluation its potential application as a dispersant for this clay. Also, the transitions from the thermoplastic to the thermoset state have been determined by thermo-gravimetric analysis (TG) and dynamicmechanical analysis (DMA) for the Poly(carboxylc acid)poly(ether-polyol) polymers alone and further by mechanical resistance measurements for a clay-polymer system. The system has presented both dispersant behavior on aqueous media and binder just afterward cure. A polymeric system thus synthesized was properly cured by heat turning and then, at the thermoset state, become suitable for act as a binder for ceramic bodies with high performance mechanical properties measured as flexural resistance at green strength.
|
168 |
Novos compósitos cerâmicos com base em caulim, borra de tinta, areia de fundição e vidros residuaisRibas, Hélverton Emílio 10 May 2017 (has links)
Resíduos industriais têm sido um dos grandes problemas ambientais discutido na atualidade. Muitos trazem em suas composições metais pesados de diversos teores, sendo necessária uma análise de cada resíduo, a fim de que se busquem soluções práticas apropriadas da destinação, e se torne um benefício ao meio ambiente. Foram elaboradas diversas composições com borra de tinta, areia de fundição, vidro e caulim, em moldes de 60mmx20mm, prensados uniaxialmente em prensa hidráulica a 10 MPa e sinterizados em forno elétrico nas temperaturas 1100°C, 1150°C, 1200°C, 1250°C e 1275ºC. Os compósitos passaram por ensaios de resistências a flexão, absorção de água, densidade aparente, retração linear, FRX, DRX, MEV, EDS, lixiviação e análise de materiais particulados. Posteriormente no material sinterizados, verificaram-se novas propriedades físicas e mecânicas, mostrando a fundição de seus materiais e resistência à flexão que chegou a 12,29 Mpa, 10,85% de absorção de água. 6,04% de retração linear e 1,39% de densidade aparente, na composição que se utilizou de 7% de resíduos e incinerados a 1275°C. Identificou a presença dos minerais montmorillonita, illita, caulinita, gibbsita, rutila e cristobalita e suas influências na cerâmica. Essa pesquisa apresentou uma solução cabível aos resíduos de tinta, areia de fundição e vidro, utilizandoos como matéria-prima para cerâmica branca. / Industrial waste has been one of the major environmental problems discussed today. Many contain in their compositions heavy metals of various contents, and an analysis of each residue is necessary in order to find appropriate practical solutions of the destination, and become a benefit to the environment. Several compositions were made with paint sludge, cast sand, glass and kaolin, in 60mmx20mm molds, uniaxially pressed in a hydraulic press at 10 MPa and sintered in an electric oven at temperatures of 1100 ° C, 1150 ° C ° C, 1200 ° C, 1250 ° C and 1275 ° C. The composites underwent tests of resistance to bending, water absorption, apparent density, linear retraction, FRX, DRX, SEM, EDS, leaching and analysis of particulate materials. Subsequently, in the sintered material, new physical and mechanical properties were found, showing the casting of its materials and flexural strength of 12.29 Mpa, 10.85% of water absorption. 6.04% linear retraction and 1.39% apparent densities, in the composition that was used of 7% of residues and incinerated at 1275 ° C. It identified the presence of the minerals montmorillonite, illite, kaolinite, gibbsite, rutila and cristobalite and their influences on ceramics. This research presented a suitable solution for waste ink, sand casting and glass, using them as raw material for white ceramics.
|
169 |
Novos compósitos cerâmicos com base em caulim, borra de tinta, areia de fundição e vidros residuaisRibas, Hélverton Emílio 10 May 2017 (has links)
Resíduos industriais têm sido um dos grandes problemas ambientais discutido na atualidade. Muitos trazem em suas composições metais pesados de diversos teores, sendo necessária uma análise de cada resíduo, a fim de que se busquem soluções práticas apropriadas da destinação, e se torne um benefício ao meio ambiente. Foram elaboradas diversas composições com borra de tinta, areia de fundição, vidro e caulim, em moldes de 60mmx20mm, prensados uniaxialmente em prensa hidráulica a 10 MPa e sinterizados em forno elétrico nas temperaturas 1100°C, 1150°C, 1200°C, 1250°C e 1275ºC. Os compósitos passaram por ensaios de resistências a flexão, absorção de água, densidade aparente, retração linear, FRX, DRX, MEV, EDS, lixiviação e análise de materiais particulados. Posteriormente no material sinterizados, verificaram-se novas propriedades físicas e mecânicas, mostrando a fundição de seus materiais e resistência à flexão que chegou a 12,29 Mpa, 10,85% de absorção de água. 6,04% de retração linear e 1,39% de densidade aparente, na composição que se utilizou de 7% de resíduos e incinerados a 1275°C. Identificou a presença dos minerais montmorillonita, illita, caulinita, gibbsita, rutila e cristobalita e suas influências na cerâmica. Essa pesquisa apresentou uma solução cabível aos resíduos de tinta, areia de fundição e vidro, utilizandoos como matéria-prima para cerâmica branca. / Industrial waste has been one of the major environmental problems discussed today. Many contain in their compositions heavy metals of various contents, and an analysis of each residue is necessary in order to find appropriate practical solutions of the destination, and become a benefit to the environment. Several compositions were made with paint sludge, cast sand, glass and kaolin, in 60mmx20mm molds, uniaxially pressed in a hydraulic press at 10 MPa and sintered in an electric oven at temperatures of 1100 ° C, 1150 ° C ° C, 1200 ° C, 1250 ° C and 1275 ° C. The composites underwent tests of resistance to bending, water absorption, apparent density, linear retraction, FRX, DRX, SEM, EDS, leaching and analysis of particulate materials. Subsequently, in the sintered material, new physical and mechanical properties were found, showing the casting of its materials and flexural strength of 12.29 Mpa, 10.85% of water absorption. 6.04% linear retraction and 1.39% apparent densities, in the composition that was used of 7% of residues and incinerated at 1275 ° C. It identified the presence of the minerals montmorillonite, illite, kaolinite, gibbsite, rutila and cristobalite and their influences on ceramics. This research presented a suitable solution for waste ink, sand casting and glass, using them as raw material for white ceramics.
|
170 |
Síntese e caracterização de macromoléculas do tipo Poli(Ácido carboxílico)-Poli(Eter-poliol) com propriedades termoplásticas e termorrígidas e avaliação de propriedades mecânicas cerâmicos à base de caulim. / Synthesis and characterization of macromolecules of the type of poly (carboxylic acid)-poly(ether polyol) with thermoplastic and thermoset properties and evaluation of mechanical properties of ceramics materials based on kaolin.José Carlos Rodrigues 27 August 2009 (has links)
Este trabalho apresenta o estudo de um sistema polimérico bi-componente formado por Poli(Ácido carboxílico)-Poli(Eter-poliol), constituído primariamente de um polímero acrílico polimerizado pelo processo de polimerização em solução aquosa por mecanismo de radicais livres ao qual foi adicionado seqüencialmente, um Poli(Eter-poliol), ambos de baixo peso molecular médio. Tal sistema tem por finalidade atuar como dispersante-ligante em sistema cerâmico à base de caulim CADAM, uma vez que este sistema apresenta propriedades termoplásticas e termorrígidas a diferentes temperaturas. Foram sintetizados 03 protótipos de um sistema polimérico e o critério para escolha teve como base o pH do sistema em sentido generalizado, isto é, compreendendo as diversas fases de preparação dos polímeros e sua aplicação final. É do conhecimento comum que a reação de esterificação entre grupos COOHOH requer catálise ácida para ocorrer, o qual usualmente é realizada em pH abaixo de 4 e, neste ensaio, este pH ácido é devido à presença de ácido para-toluenosulfônico, que atua como catalisador de esterificação. Em tal intervalo de pH, em virtude do ponto isoelétrico do caulim ser comumentemente abaixo de 4, a estabilização da dispersão de caulim por repulsão eletrostática utilizando polímeros sintéticos é improvável de ocorrer, razão pela qual buscou-se mecanismos alternativos para obtenção de uma tal estabilização, entre os quais o mecanismo estérico surge como opção. O sistema polimérico do presente estudo apresenta-se na forma de uma solução aquosa sendo, de fato, uma mistura homogênea de um copolímero de ácido acrílico, N- metiloacrilamida e metacrilato de metoxipolietileno glicol e um poli(eter-poliol). O poli(eter-poliol) e N-metilolacrilamida presentes no sistema polimérico são principais fontes de grupo hidroxila para reação de poliesterificação e formação de ligações cruzadas à temperatura de 150 a 200 °C. No estado termoplástico o sistema polimérico produzido pela mistura poli(ácido carboxílico)-poli(eter-poliol) pode ser utilizado como dispersante de argilas com especial fóco sobre caulim como tratado neste trabalho. A propriedade dispersante pode ser atribuida à presença de grupos carboxílicos e metoxipolietilenoglicol aleatoriamente distribuídos ao longo da cadeia polimérica e, também, ao baixo peso molecular médio. A temperaturas entre 150 a 200 °C, o polímero é reticulado (crosslinked) por reação de poliesterificação, catalisada por ácido, entre grupos carboxila e grupos hidroxila, sendo as hidroxilas provenientes tanto de poliol como de N-metilolacrilamida (NMAM). Assim, do ponto de vista térmico comporta-se como termorrígido, sendo nesta condição insolúvel em água e adequado atuar como ligante na manufatura de materiais cerâmicos. Medidas de mobilidade eletroforética e viscosidade são aplicadas à caracterização de caulim e do sistema polimérico a fim de avaliar a potencialidade de aplicação como dispersante desta argila. Também, as transições dos estados termoplásticos para termorrigidos foram determinadas por análise termogravimétrica (TG) e análise dinâmico mecânica (DMA) nos polímeros isoladamente e depois com medidas de resistência mecânica do sistema caulim/polímero. O sistema apresentou comportamento dispersante em água e ligante após cura. Um sistema polimérico assim sintetizado foi propriamente curado por calor tornando- se, na forma termorrígida, um ligante para peças cerâmicas com propriedades mecânicas de alto desempenho, como resistência a flexão no estado cru (green strenght). / This work presents the study of a polymeric bi-component system made from Poly(carboxylic acid)-Poly(ether-polyol) primarily constituted of an acrylic acid polymerized through the process of aqueous solution polymerization by free radical mechanism, to which a poly(ether-polyol) has been sequentially added, both of them of low average molecular weight. Such a system has the aim to act as dispersing-binding balance on CADAM kaolin targeting to evaluate the applicability potential or the preparation of ceramic bodies as this polymeric system presents thermoplastic and thermosetting properties at different temperatures. Were made the synthesis of 03 polymeric system prototypes which criteria for choice was based on pH of the system at whole sense, that is, regarding the several steps for polymers preparation and its final application. It is knowledge that esterification reaction between COOH-OH groups requires acid catalyst to occur, which usually is done at pH below 4 and, in this work this pH is due to p-toluene sulfonic acid that act as esterification catalyst. In this range of pH, due to the isoeletric point of kaolin to be below 4 the electrostatic stabilization of dispersion is unlikely to occur, from which reason was looked for an alternative mechanism to achieve the dispersion stabilization, among them the steric mechanism arises an option. The polymeric system of this study is the form of an aqueous solution, which actually is a homogeneous blend of a copolymer of acrylic acid, N-Methylolacrylamide Methoxypolyethyleneglycol Methacrylate (MPEGMA) and Poly(ether-polyol). The Poly(etherpolyol) and the N-Methylolacrylamide presents at the polymeric system are the main sources of hydroxyl groups to enhance the polyesterification reaction for further crosslinking at temperatures from 160 to 200 °C. At the thermoplastic state the polymeric system made by Poly(carboxilic acid)poly(ether-polyol) macromolecules may be used as clay dispersant focusing on kaolin for this work. The dispersant property may be attributed to the carboxylic and methoxypolyethyleneglycol group randomly distributed along the polymeric chain backbone and, also to the low average molecular weight. At temperatures between 150 to 200 °C, the polymer is crosslinked by polyesterification reaction catalized by acid between carboxyl groups and hydroxyl groups, in such way that hydroxyls groups comes both from the polyol base polymer and NMethylolacrylamide (NMAM) present at first polymer backbone. Thus, through a thermal standpoint it behaves as thermoset being that, under this condition, water insoluble and adequate to act as binder for manufacturing of ceramic materials. Electrophoretic mobility and viscosity measurements were applied for the characterization of kaolin and the polymeric system targeting to the evaluation its potential application as a dispersant for this clay. Also, the transitions from the thermoplastic to the thermoset state have been determined by thermo-gravimetric analysis (TG) and dynamicmechanical analysis (DMA) for the Poly(carboxylc acid)poly(ether-polyol) polymers alone and further by mechanical resistance measurements for a clay-polymer system. The system has presented both dispersant behavior on aqueous media and binder just afterward cure. A polymeric system thus synthesized was properly cured by heat turning and then, at the thermoset state, become suitable for act as a binder for ceramic bodies with high performance mechanical properties measured as flexural resistance at green strength.
|
Page generated in 0.0626 seconds