Orientador: Liliane Maria Ferrareso Lona / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-07T23:37:08Z (GMT). No. of bitstreams: 1 Franco_IvanCarlos_M.pdf: 1044560 bytes, checksum: 8f4fdd66626d63245a2131f55b09f807 (MD5) Previous issue date: 2007 / Resumo: Polimerização via radical livre controlada (CRP) tem recebido cada vez mais atenção como uma técnica para produção de polímeros com micro estrutura altamente controlada. Em particular, distribuições de pesos moleculares estreitas são obtidas, com polidispersidade muito próxima de um, sendo um campo promissor na ciência de polimerização com estruturas controladas. Um importante requisito para engenharia de polimerização e desenvolvimento de polímeros é a construção de modelos matemáticos úteis, especialmente aqueles de natureza mecanística, com validação experimental. O objetivo deste trabalho é o desenvolvimento de modelos matemáticos abrangentes para simulação de polimerização para mecanismo RAFT. Metacrilato de metila em benzeno a 60°C na presença de 2,2-cianopropil 1- pirrolecarboditioato (agente RAFT) e com AIBN como iniciador em um reator batelada será considerado como estudo. Os pesos moleculares foram calculados utilizando o método dos momentos. Uma análise paramétrica considerando o efeito da concentração de iniciador e da concentração de agente RAFT foi realizada. O modelo predito está de acordo com os dados experimentais da literatura, o que atesta sua validade para ser utilizado no controle de estruturas poliméricas obtidas no processo RAFT / Abstract: Lately, Living Free Radical Polymerization (LFRP) has been detached as a technique for the production of polymers with highly controlled microstructure. In particular, narrow distributions of molecular weights are obtained, with polydispersity values next to one. So, this technique is a promising field in the science of polymerization with controlled structures. An important requirement for engineering of polymerization and polymer development is the construction of useful mathematical models, especially those of mechanistic nature, with experimental validation. The objective of this work was to develop comprehensive mathematical models to simulate polymerization from RAFT mechanism. Methyl Methacrylate in benzene at 60°C in the presence of 2-cyanoprop-2-yl 1-pyrrolecarbodithioate (agent RAFT) and with AIBN as the initiator in a batch reactor was considered. The molecular weights have been calculated using the method of moments. A parametric analysis considering the effect of the initiator and agent RAFT concentrations was performed. Models prediction showed good agreements with experimental data from literature, what certifies its validity in being used in the control of polymeric structures in RAFT process / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientadores: Wander José da Silva, Altair Antoninha Del Bel Cury / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-27T04:08:04Z (GMT). No. of bitstreams: 1 Panza_LeonardoHenriqueVadenal_D.pdf: 39498694 bytes, checksum: bcb5576864f239980a74f85ecab13ee6 (MD5) Previous issue date: 2015 / Resumo: O uso de PPRs continua como uma alternativa viável e eficiente na prática da reabilitação oral, no entanto a necessidade do uso de uma estrutura metálica, pode muitas vezes causar um comprometimento estético. O uso de materiais alternativos flexíveis para a substituição destes grampos ou de outras partes da PPR tem sido bastante divulgado, porém ainda existem controvérsias sobre as propriedades físicas e mecânicas dos mesmos. O objetivo deste trabalho foi comparar 2 materiais utilizados na confecção de PPRs nos quesitos sorpção de água, solubilidade em água e transmissão de forças ao rebordo na extensão distal da peça. Para análise de sorpção e solubilidade foram confeccionados discos em polimetilmetacrilato (PMMA) e poliamida (POL), seguindo as especificações da ISO 1567. Para análise da transmissão de forças ao rebordo foram confeccionados modelos classe I de Kennedy em resina fotoelástica e 3 diferentes tipos de PPR: tradicional com estrutura metálica e base em PMMA (controle), PPR conjugada feita com estrutura metálica e poliamida e uma PPR confeccionada totalmente em poliamida. Os conjuntos modelo-PPR foram submetidos à cargas de 0,5 e 1,0 KgF na extensão distal e as imagens de franjas formadas nos modelos foram capturadas de forma padronizada. O teste de Kruskal-Wallis foi utiilizado para analisar os dados, que mostraram não haver diferenças significantes entre os materiais para sorpção de água (p=0.6682) e solubilidade (p=0.4095). A análise fotoelástica mostrou uma transmissão de forças mais intensa pela extensão distal da PPR nos grupos de PPRs feitas em poliamida, quando comparadas ao grupo controle, especialmente no grupo da PPR sem metal. Com as limitações deste estudo foi possível concluir que o comportamento do PMMA e da poliamida foi similar para sorpção e solubilidade em água e que a transmissão de forças ao rebordo em próteses confeccionadas em poliamida sem metal contraindicam o seu uso / Abstract: The use of removable partial denture (RPD) still remains as a viable alternative to an efficient oral rehabilitation. However, due the metal framework lack of esthetic, it has been suggested the use of flexible materials as substitutes to the metal clasps, even thought this material maintains controversial regarding its dimensional properties. In this manuscript, our group compared two materials used in the fabrication of RPD regarding its water sorption and solubility and load transmission by distal extension. For this, poly (methyl methacrylate) (PMMA) and polyamide (POL) discs (n=7) were used to manufacture specimens that were evaluated regarding its water sorption and solubility. For load transmission by distal extension, Kennedy Class I mandibular models were made with photo elastic resin and 3 different RPD were tested: traditional RPD with metal framework and PMMA flange (Control); RPD with metal framework and clasps and flange in POL (POL-Metal); and RPD totally manufactured in POL (TOT-POL). Load of 0.5 and 1.0 kgF were applied to distal extension and the image of the load transmission in the photo-elastic model was captured. Kruskal-Wallis test were used for data analysis. Results showed no statistical difference between both materials regarding water sorption (p=0.6682) and solubility (p=0.4095). Photo-elastic analyses showed higher load transmission by distal extension by both POL group when compared to control group. Within the limitations of this study, it can be concluded that although POL had similar behavior to PMMA regarding water sorption and solubility, the load transmission by distal extension in RPD manufactured with POL shows the worst results, but clinical studies should de done with this material to indicates its use / Doutorado / Protese Dental / Doutor em Clínica Odontológica

Orientador: Maria Isabel Felisberti / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T10:02:17Z (GMT). No. of bitstreams: 1 Camilo_AnaPaulaRodrigues_D.pdf: 5133828 bytes, checksum: 99ef787814cdea2e327eb67879a8eec7 (MD5) Previous issue date: 2015 / Resumo: Neste trabalho foram sintetizados copolímeros anfifílicos dibloco baseados em 1¿-O-metacrilato de sacarose (SMA) e metacrilato de metila (MMA) por RAFT (Reversible Addition-Fragmentation Chain Transfer) e ATRP (Atom Transfer Radical Polymerization) com diferentes composições (balanço hidrofílico/hidrofóbico diferenciado). O MMA é um monômero hidrofóbico, enquanto, o SMA apresenta caráter fortemente hidrofílico. Primeiramente, foi realizado um estudo referente aos parâmetros reacionais utilizados na síntese do bloco de MMA, tanto via RAFT quanto ATRP. Para a polimerização RAFT, avaliou-se a influência da razão molar entre os reagentes, da temperatura e do solvente sobre a eficiência na polimerização. Na polimerização ATRP estudou-se sistemas reacionais contendo diferentes iniciadores, ligantes e catalisadores. A partir desse estudo, adotou-se os sistemas catalisador/iniciador, brometo de cobre (I)/ 2,2,2-tribrometanol (CuBr/TriBrEt), e agente de transferência/iniciador, ditiobenzoato de 2-cianopropila/2,2?-azoisobutironitrila (CPDB/AIBN), para a polimerização ATRP e RAFT, respectivamente. Estes sistemas mostraram ser eficazes tanto para a obtenção do homopolímero PMMA, quanto para os copolímeros em bloco P(MMA-b-SMA), com polidispersidade controlada. Os homopolímeros (PMMA) e os copolímeros dibloco P(MMA-b-SMA) foram caracterizados estruturalmente por ressonância magnética nuclear de 13C (RMN 13C) e cromatografia de permeação em gel (GPC). As propriedades físico-químicas dos copolímeros no estado sólido foram avaliadas por análise termogravimétrica (TGA), análise dinâmico-mecânica (DMA), difratometria de raios-X de alto ângulo (DRX) e espalhamento de raios-X de baixo ângulo (SAXS). A morfologia foi estudada por microscopia de força atômica (AFM) e microscopia eletrônica de transmissão (TEM). O comportamento de soluções dos copolímeros em DMF foi estudado por SAXS. Todos os polímeros sintetizados se apresentaram solúveis em DMF, evidenciando que tratam-se de macromoléculas não-reticuladas, revelando que o caráter anfifílico é fortemente dependente da composição, tal como era esperado. As propriedades físico-químicas dos copolímeros sólidos e em solução, assim como a morfologia, mostraram-se dependentes da composição. A combinação dos resultados das análises de RMN 13C, DMA, AFM e TEM, para os copolímeros, permitiu concluir que o bloco de PMMA constitui-se a fração majoritária, que os blocos PSMA e PMMA são imiscíveis, e que a morfologia é a de uma matriz constituída predominantemente por PMMA, na qual a fase PSMA minoritária encontra-se dispersa, respectivamente. Resultados de estudos por RMN 13C e SAXS mostraram que, dependendo da composição, os copolímeros tendem a se organizar em solução ou na forma sólida. Os resultados de SAXS e de AFM de filmes dos copolímeros também indicaram que a dispersão da fase PSMA na matriz de PMMA ocorre de forma distinta, de acordo com o solvente utilizado no processo casting / Abstract: In this work, amphiphilic diblock copolymers based on sucrose 1'-O-methacrylate (SMA) and methyl methacrylate (MMA) with different compositions (differentiated hydrophilic/hydrophobic balance) were synthesized by RAFT (Reversible Addition-Fragmentation Chain Transfer) and ATRP (Atom Transfer Radical Polymerization). Methyl methacrylate (MMA) is a hydrophobic monomer, while the 1'-O-sucrose methacrylate (SMA) is strongly hydrophilic. The first step of the studies concerned the influence of the reaction parameters on the synthesis of the MMA block, using both RAFT and ATRP. For RAFT polymerization, the influence of the molar ratio between the reactants, temperature and solvent on the efficiency of polymerization was evaluated. For the ATRP polymerization four different combinations of initiators/ligants/catalysts were studied and their efficiency were compared. From this study, systems catalyst/initiator, copper (I) bromide/2,2,2-tribromethanol (CuBr/TriBrEt), and transfer agent/initiator, (2-cyanopropyl) dithiobenzoate/2,2?-azobis(2-methylpropionitrile) (CPDB/AIBN), were used for ATRP and RAFT polymerization, respectively. These systems showed to be effective to obtain PMMA homopolymer and block copolymers P(MMA-b-SMA) with controlled polydispersity. The homopolymers (PMMA) and diblock copolymers P(MMA-b-SMA) were structurally characterized by 13C nuclear magnetic ressonance (13C NMR) and gel permeation chromatography (GPC). The physico-chemical properties of the copolymers in the solid state was evaluated by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS). The morphology was studied by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The behavior of copolymers in solutions of the DMF was studied by SAXS. All copolymers were soluble in DMF, showing that they are non-crosslinked macromolecules, revealing that the amphiphilic character is strongly dependent of the composition, as expected. From 13C NMR, DMA, AFM and TEM analysis of the copolymers it was possible conclude that PMMA block is a majority component, PSMA and PMMA blocks are miscible and the morphology is predominantly composed of a PMMA matrix, in which the minority PSMA phase is dispersed, respectively. The results of studies by 13C NMR and SAXS showed that some compositions of the copolymers are self-organized in solution and in solid state. The results of SAXS and AFM indicated that the dispersion of the PSMA phase in the PMMA matrix occurs differently, according with the solvent used in the casting process / Doutorado / Físico-Química / Doutora em Ciências

Nanocompósitos de PMMA/ argila montmorilonita foram obtidos por fotopolimerização in situ. O metacrilato de metila foi polimerizado na presença de argilas modificadas usando Tioxantona (TX) e etil 4-(dimetilamino) benzoato (EDB) como sistema fotoiniciador. As argilas montmorilonitas SWy-1 modificadas, SWy-1-C8 e SWy-1-C16, foram preparadas pela troca de íons com brometo de octiltrimetilamônio (C8) e brometo de hexiltrimetilamônio (C16), respectivamente. A difração de raios-X indicou que os compósitos de PMMA/argila podem ter estruturas intercaladas ou esfoliadas, ou mesmo uma mistura de estruturas em camadas esfoliada e parcialmente intercalada. A estrutura de cada nanocompósito depende da concentração de argila e do solvente utilizado na preparação. A influência da concentração de argila organofílica, natureza do solvente e tipo de argila nas propriedades térmicas e mecânicas foi estudada por análise termogravimétrica e análise dinâmico-mecânica. Todos os nanocompósitos preparados em acetonitrila exibiram melhora da sua estabilidade térmica, principalmente devido à interação entre a argila e o polímero que é maximizada através da estrutura da argila esfoliada. No caso do PMMA e nanocompósitos sintetizados em etanol, a estabilidade térmica do polímero e nanocompósitos foi praticamente a mesma, uma vez que a estrutura da argila é predominantemente do tipo intercalada. Na velocidade de polimerização observou-se que os fatores que mais influenciaram foram a concentração de argila e o tipo de solvente. A argila proporciona a formação de microambientes que estabilizam o estado excitado do iniciador formando mais radicais livres e consequentemente aumentando a velocidade polimerização. A utilização da acetonitrila, a qual é um melhor solvente para o PMMA proporcionou massas molares menores. A degradação foto-oxidativa dos nanocompósitos de PMMA/ argila foi investigada utilizando cromatografia de exclusão de tamanho (SEC). Foram encontradas evidências de que o PMMA e nanocompósitos degradam por cisões aleatórias de cadeias. A polidispersidade aumentou após a irradiação e o coeficiente de degradação de PMMA puro é de até seis vezes maior do que para os nanocompósitos. O efeito sobre os coeficientes de fotodegradação da concentração de argila, tipo argila (argila modificada por agentes tensoativos com diferentes comprimentos de cadeias de alquílica) e o solvente utilizado para a dispersão de argila orgânica, também foram estudados. / Montmorillonite clay/PMMA nanocomposites were obtained by in situ photopolymerization. Methyl methacrylate was polymerized in the presence of modified clays using thioxanthone (TX) and ethyl 4-(dimethylamino) benzoate (EDB) as photoinitiating system. The SWy-1 montmorillonite modified clays, SWy-1-C8 and SWy-1-C16, were prepared by ion exchange with octyltrimethylammonium bromide (C8) and hexyltrimethylammonium bromide (C16), respectively. X-ray diffraction indicated that clay/PMMA composites have intercalated or exfoliated structures, or even a mixture of exfoliated and partially intercalated structure layers. The structure of each particular nanocomposite depends on the clay loading and the solvent used for the preparation.The influences of organoclay loading, solvent nature and clay type on thermal and mechanical properties were studied by thermogravimetric analysis and dynamic mechanical analysis. All the nanocomposites prepared in acetonitrile exhibited improvement in their thermal stability, mainly due to the interaction between the clay and the polymer which is maximized by the exfoliated clay structure. In the case of PMMA and nanocomposites synthesized in ethanol, the thermal stability of polymer and nanocomposites remained practically the same once the clay structure is predominantly of the intercalated type. It was observed that the factors that most influenced the polymerization rate were the concentration of clay and type of solvent. The clay provides the formation of microenvironments that stabilizes the excited state of the initiator forming free radicals and consequently increasing the polymerization rate. The use of acetonitrile, which is a better solvent for PMMA gave the lowest molar weight. The photooxidative degradation of clay/PMMA nanocomposites has been investigated using size exclusion chromatography (SEC). Evidence was found that PMMA and composites degrade by random chain scissions. The polydispersity increases after irradiation and the degradation rate coefficient for pure PMMA is up to 6 times larger than that for the composites. The effect on the photodegradation rate coefficients of the clay content, clay type (clay modified by surfactants with different lengths of alkyl chains) and solvent used for dispersion of organic clay were also studied. The relationship of these parameters on the photodegradation process was statistically evaluated using a two-level factorial design.

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Ever since their discovery, Carbon nanotubes (CNTs) have been renowned to be potential candidates for a variety of applications. Nevertheless, the difficulties accompanied with their dispersion and poor solubility in various solvents have hindered CNTs potential applications. As a result, studies have been developed to address the dispersion problem. The solution is in modifying the surfaces of the nanotubes covalently or non-covalently with a desired dispersant. Various materials have been employed for this purpose out of which polymers are the most common. Non-covalent functionalization of CNTs via polymer wrapping represents an attractive method to obtain a stable and homogenous CNTs dispersion. This method is able to change the surface properties of the nanotubes without destroying their intrinsic structure and preserving their properties. This thesis explores and studies the surface modification and solublization of pristine single and multiwalled carbon nanotubes via a simple solution mixing technique through non-covalent interactions of CNTs with various anionic and cationic conjugated polyelectrolytes (CPEs). The work includes studying the interaction of various poly(phenylene ethynylene) electrolytes with MWCNTs and an imidazolium functionalized poly(3-hexylthiophene) with SWCNTs. Our work here focuses on the noncovalent modifications of carbon nanotubes using novel CPEs in order to use these resulting CPE/CNT complexes in various applications. Upon modifying the CNTs with the CPEs, the resulting CPE/CNT complex has been proven to be easily dispersed in various organic and aqueous solution with excellent homogeneity and stability for several months. This complex was then used as a nanofiller and was dispersed in another polymer matrix (poly(methyl methacrylate), PMMA). The PMMA/CPE/CNT composite materials were cast or electrospun depending on their desired application. The presence of the CPE modified CNTs in the polymer matrix has been proven to enhance the composites thermal, mechanical and electrical properties compared to pristine CNTs. Various spectroscopic and microscopic techniques such as UV-vis, fluorescence, TEM, AFM and SEM were used to study and characterize the CPE/CNT complexes. Also, TGA, DSC and DMA were used to study the thermal and mechanical properties of the composite materials. Our current work represents a fundamental study on the non-covalent interactions between CNTs and CPEs on one hand and gives a real life example on the CPE/CNT application in composite materials and electronics.

Today, structural adhesives are found extensively in load-bearing engineering applications, as their use can be advantageous compared to other fastening methods. However, the characteristics of adhesives are far more complex, making it challenging to predict their behavior in different service conditions. In addition, environmental factors like temperature and water can affect the performance of an adhesive bond both physically and chemically. This work was initiated by MuoviTech AB and aims to evaluate the performance of structural methyl methacrylate adhesives cured in different environmental conditions. The study began with a literature review to find relevant research and literature about structural adhesives, their material characteristics, and the effects of temperature and water on the performance of adhesive bonds. A market survey was conducted to find products suitable for the experiment, and Araldite 2050, Araldite 2051, Permabond TA4200, 3M DP8810NS, LoctiteHY 4070, and Acralock SA 10-05 were selected together with MuoviTech AB. The laboratory work began with sample preparation in terms of abrasion and cleaning of the surface. The adhesives were applied to the samples, and single-lap joints were prepared and cured in room temperature and normal humidity, as well at 5 °C and underwater, for 24 hours. Single-lap shear tests were performed according to American standard ASTM D3163. Lastly, differential scanning calorimetry (DSC) was utilized for the thermal analysis of the samples cured at 5 °C and underwater. The results showed that neither of the adhesives performed in the range specified in the manufacturers’ technical data sheets (TDS). Lower failure strength and elongation was observed for the samples cured at 5 °C and underwater, compared to the samples cured in the optimal condition. However, Loctite HY 4070 showed an increase in failure strength. The DSC analysis revealed various degrees of post-curing. Further investigation with prolonged curing time and more environmental conditions are recommended. New tests for Loctite HY 4070 is also recommended to confirm the results. / Idag finns strukturella lim i stor utsträckning i bärande tekniska applikationer, eftersom deras användning kan vara fördelaktig jämfört med andra fästmetoder. Limmens egenskaper är dock mycket mer komplexa, vilket gör det svårt att förutsäga deras beteende under olika serviceförhållanden. Dessutom kan miljöfaktorer som temperatur och vatten påverka en limbindnings prestanda både fysiskt och kemiskt. Detta arbete initierades av MuoviTech AB och syftar till att utvärdera prestanda för strukturella metylmetakrylatlim härdade under olika miljöförhållanden. Studien inleddes med en litteraturöversikt för att hitta relevant forskning och litteratur om strukturella lim, deras materialegenskaper och effekterna av temperatur och vatten på limförbandens prestanda. En marknadsundersökning genomfördes för att hitta produkter som var lämpliga för experimentet, och Araldite 2050, Araldite 2051, Permabond TA4200, 3MDP8810NS, Loctite HY 4070 och Acralock SA 10-05 valdes tillsammans med MuoviTech AB. Arbetet i laboratoriet inleddes med provförberedelse genom slipning och rengöring av provens yta. Lim applicerades på proverna och förband med enkla överlapp (single-lap) bereddes och härdades i rumstemperatur och normal fuktighet, liksom vid 5 ° C och under vatten, under 24 timmar. Skjuvtester utfördes enligt den amerikanska standarden ASTM D3163. Slutligen användes differentiell svepkalorimetri (DSC) för termisk analys av proverna som härdades vid 5 ° C och under vatten. Resultaten visade att inget av limmen presterade i enlighet med det som beskrevs i tillverkarnas tekniska datablad (TDS). Däremot så observerades en lägre brottstyrka och töjning för proverna som härdades vid 5 ° C och under vatten, jämfört med de prover som härdades i det optimala tillståndet. Loctite HY 4070 visade emellertid en ökning av brottstyrka. DSC-analysen gav indikation på att olika grader av efterhärdning. Ytterligare undersökningar med längre härdningstid och med flera miljöförhållanden rekommenderas. Nya tester för Loctite HY 4070 rekommenderas också för att bekräfta resultaten.

The purpose of this work was the synthesis of functional amphiphilic gradient copolymers by means of controlled radical polymerizations, more precisely Atom Transfer Radical Polymerization. Two different monomer combinations, tert- and n-butyl methacrylate and tert-butyl and benzyl methacrylate, were copolymerized. In a first step seven different linear statistical copolymers were synthesized by means of batch polymerization. They were used as comparative material and the analysis of the reaction kinetic yielded the effective rate constants and the copolymerization parameters of the monomers in the particular monomer systems. Furthermore required for gradient polymer syntheses AB-di-block copolymers were synthesized as a second kind of comparative material. With the results of the kinetic analysis the monomer addition programs for the semibatch polymerizations were calculated to prepare gradient copolymers. Four different gradient copolymers with different compositions of tBMA and nBMA (ftBMA= 0.5, 0.65, 0.75, 0.85) and one gradient copolymer of tBMA and BzMA (ftBMA= 0.5) were synthesized. All semibatch reactions proceeded controlled, i. e. with mostly suppressed termination reactions. The compositions of the resulting copolymers exhibited ''double-gradients''. The point of change of the compositions were located at 16%, respectively 11% of conversion. The effective compositional gradients φ = dF1/dp were φ = 0.53, 0.46, 0.28, 0.15 and 0.43. A systematic correlation between the thermal behavior of the gradient copolymers and their composition was not found, as opposed to the statistical and the di-block copolymers. Semibatch synthesis with online infrared-spectroscopy observation to control the monomer feed during the synthesis were used for the polymerization of gradient copolymers. It was not possible to calculate the change of compositions of the polymers because it was not known how much monomer was injected at a certain time of the polymerization. A second problem was that the experimental set-up was not gas-tight. Hence, oxygen led to termination reactions. Three different kinds of hydrolysis were investigated for the cleavage of the tert-butyl groups on the polymer chains. The obtained gradient copolymers were hydrolyzed with methanesulfonic acid to obtain the intended amphiphilic polymer chains. All reactions proceeded with quantitative conversion. Hence, functional amphiphilic copolymers were obtained.

No description available.