The design, fabrication, and characterization of polymer-carbon nanotube (CNT) composites have generated a significant amount of attention in the fields of materials science and polymer chemistry. The challenge in fabricating composites that exploit the unique properties of the CNT and the ideal processing ability and low cost of the polymer is in achieving a uniform dispersion of the filler in the polymer matrix. This body of work focuses on (1) techniques employed to disperse CNTs into a polymer matrix and (2) the effects of CNTs on the mechanical and electrical properties of the polymer. Poly (methyl methacrylate) (PMMA), an amorphous polymer, and poly (4-methyl-1-pentene) (P4M1P), a semi crystalline polymer, were chosen as the matrices. Non-functionalized single-walled carbon nanotubes and soot (unpurified carbon nanotubes) were chosen as the filler material. In the first study, single-walled carbon nanotubes (SWNTs) were sonicated in methyl methacrylate monomer and initiated via thermal energy, UV light, and gamma radiation. Composite films with increased dielectric constants and unique optical transparency were produced. Samples were characterized using differential scanning calorimetry, dielectric analysis, and dynamic mechanical analysis. Refractive Indices were obtained and correlated to the dielectric constant using Maxwells relationship. PMMA/soot composites were fabricated in the second study. Dispersion was accomplished by way of sonication and melt compounding. The PMMA/soot composites were exposed to gamma radiation, with a 137Cs gamma source, in order to investigate how the filler affects the polymers ability to resist radiation. Samples were characterized by differential scanning calorimetry, dielectric analysis, and dynamic mechanical.

Matrix Assisted Laser Desorption Ionization–Time of Flight (MALDI-TOF) mass spectroscopy is used in the characterization of synthetic polymers. MALDI allows for determination of: modal, most probable peak (M P), molecular number average (MN), molecular weight average (MW), polydispersity (PD), and polymer spread (PSP). We evaluate a new sample preparation method using Induction Based Fluidics (IBF) to kinetically launch and direct nanoliter volumes to a target without contact. IBF offers signal improvement via field enhanced crystallization. This is the first study to discuss filed enhanced crystallization in MALDI sample preparation. IBF can increase signal/noise (S/N) and signal intensity for polystyrene (PS), poly(methyl methacrylate) (PMMA), and poly(ethylene glycol) (PEG) across a mass range of 2,500 to 92,000 Da showing more accurate PSP. Increases in S/N range up to: 279% for PS, 140% for PMMA, and 660% for PEG. Signal intensities increased up to: 438% for PS, 115% for PMMA, and 166% for PEG. Cross-polarization microscopy indicates dramatic morphology differences between IBF and micropipette. Finally, we speculate as to why IBF nanoliter depositions afford higher S/N values in experiments conducted in different instrumental configurations even without optimization. Next we sought to investigate whether nanoliter volumes of concentrated polar liquids and organic monomers launched to targets using IBF can be verified through the real time charge measurements. We show that using a nanoliter IBF dispensing device and nanocoulomb meter, charge measurements made on nanoliter drops in real time are correlated with the droplets surface area following Gauss’s Law. We infer the "induction only" formation of the double layer showing the ability to determine nanoliter volumes, nearly instantaneously, in real time. Implications are presented from these IBF measurement observations on improving/monitoring MALDI quantitation and its quality control. Polymer-dye interactions were further investigated using PMMA composites made from a polar metalloporphyrin [5-(4',4',5',5'-tetramethyl[1',3',2']dioxaborolan-2'-yl)-10,20-diphenylporphyrinato]zinc(II) (Zn(II)Bpin-DPP) in select weight %s (wt%s). Fluorescence spectroscopy has revealed that the porphyrin was well dispersed within the composite. Differential Scanning Calorimetry (DSC) showed that porphyrin acted as an antiplasticizer raising the glass transition (Tg) from 105 °C to 123 °C. Dielectric Analysis (DEA) was performed in the frequency range of 0.3 Hz to 100 kHz between -150 to 270 ⁰C. Permittivity (ε’), loss factor (ε’’) and dielectric response of beta (β), alpha beta (αβ), and conductivity relaxations were studied. Previous DEA data was limited to 190 ⁰C. This study brings analysis to 270 ⁰C which is start point for the first part of PMMA degradation. Thus forwarding DEA can be used to evaluate PMMA degradation. The electric modulus formalism is used to reveal the β and conductivity relaxations. The apparent activation energies (Ea) for the molecular relaxations are presented. AC (ζAC) and DC (ζDC) conductivity are also evaluated. Tan delta (δ), dissipation factor, evaluated between 1 Hz to 100 kHz was shown to increase with porphyrin loading although locally affected by free volume restriction. Havriliak-Negami (H-N) equation was fit using the complex electric modulus (M*) modified form and was performed on the conductivity region 160 to 190 ⁰C and degradation region 190 to 270 °C. Relaxations above the Tg were proven to be conductivity relaxations using four proofs. This is the first study to investigate PMMA degradation DEA with the complex electric modulus, M*, revealing a unique occurrence of increasing central relaxation times (s-1) and reducing electric loss modulus (M") frequency maxima (Hz) after the degradation temperature of 220 ⁰C was reached supporting current literature of the first of a two part degradation process that proceeds via end chain scission.

Nanocellulose is an interesting natural material thatis gaining interest in the field of materials science, particularly nanocomposites. Depending on the disintegration route, nanocellulose can be isolated either in the form of long and flexible fibres (nanofibrillated cellulose, NFC), or stiff, rod-like crystals (cellulose nanocrystals, CNC). Nanocellulose can be utilized in nanocomposites either as a reinforcement element or as a network matrix due to its ability to form a strong network. In this thesis, nanocellulose based materials are prepared by evaporation of a liquid medium. The key step in this processing route is a good dispersion of the nanoparticles in the selected matrix. Therefore the importance of surface modification in order to ensure favourable nanocellulose dispersion is clarified in avariety of materials systems. In Paper I, poly(methyl methacrylate) (PMMA) based fibres prepared by electrospinning were reinforced with nanofibrillated cellulose. Native NFC appeared to show a good compatibility with PMMA matrix in the electrospinning solution and resulting fibres. Furthermore, a new method for mechanical testing of mats with random fibre orientation as well as aligned fibres was developed. In Paper II, commingled nanopaper structures with carbon nanotubes (CNTs) were prepared. Several surfactants were used to disperse hydrophobic CNTs in water. A nonylphenol phosphate ester (NPPE) was found to work well for both dispersing CNTs in water and providing compatibility with NFC through electrostatic repulsion between the phosphate ester groups of the surfactant and the carboxylate groups of NFC. In Paper III, a new water based route for functionalization of cellulose nanocrystals was developed. In this approach, inspired by organo-modified layered silicates, quaternary ammonium salts were adsorbed. It was demonstrated that different functionalities (alkyl, phenyl, glycidylor diallyl) can be introduced onto the cellulose and the dispersibility in organic solvents was studied. Subsequently, in Paper IV, nanocomposites with poly(vinyl acetate) (PVAc)were prepared. The effect of modification on the degree of dispersion of the CNC within the matrix was studied as well as the strong effects on the properties of the resulting nanocomposites. In Paper V, taking advantage of the entangled NFC network and the possibility to tailor the pore size and surface chemistry, lubricant-infused slippery films and coatings based on NFC were prepared for the first time. / <p>QC 20131016</p>

In this study, ethyl methacrylate was polymerized by free radical polymerization at 600C, 700C, 800C at open atmosphere / atom transfer radical polymerization, (ATRP), at 800C in vacuum and in gamma irradiation in vacuum. The polymer obtained was white, hard material. The kinetic curves for free radical polymerization and ATRP by gamma radiation were S-type. However, the curve for polymerization by gamma irradiation raises more smoothly. For ATRP by thermal initiation gives a lineer change of conversion with time. It was observed that the molecular weight can be controlled and low molecular weight polymer could be obtained by ATRP method. The characterization of polymers were made by FTIR, DSC, 1H and 13C NMR techniques.

ABSTRACT Covalent Immobilization of Glucose Isomerase on Poly (2-hydroxyethyl methacrylate) Particles Yildiz, Hakan &Uuml / mit M.S., Department of Chemistry Supervisor: Prof. Dr. Nesrin Hasirci July 2004, 54 pages In this study, poly (2-hydroxyethyl methacrylate), P(HEMA), particles were prepared by suspension polymerization of the monomer 2-hydroxyethyl methacrylate with addition of ethylene glycol dimethyacrylate, EGDMA, as cross linker. Glucose isomerase, GI, enzyme was covalently immobilized on the prepared P(HEMA) particles after activation of the particles with cyanuric chloride. The activities of the free and immobilized enzymes were measured with Ethanol-Carbazole method. The immobilization of GI on P(HEMA) particles promoted enzyme stability and as a result, the enzyme became more stable to temperature, storage, and reuse. For maximum substrate conversion, optimum temperature was determined as 70 oC for free GI and this value shifted to 60 oC for immobilized enzyme. Optimum pH for maximum substrate conversion was found to be 7.0 for free GI and 8.0 for immobilized GI. The change of enzyme activity with substrate concentration were determined to calculate Km and Vmax values of the free and immobilized enzymes. Km values were found to be 1.7x10-2 mol/L and 3.1x10-1 mol/L while Vmax values were 1.01x10-4 mol/L.min, 1.65x10-3 mol/L.min for free and immobilized GI, respectively. Reuse capability of immobilized GI on P(HEMA) particles was measured and compared with commercial GI. Both systems retained 80 % of their original activities after 40th use, within 6 days. The change of enzyme activities upon storage were detected at certain time intervals for the samples stored in buffer solution at 4 oC. Immobilized enzyme was retained 60% of its original activitiy in 60 days of storage at 4 oC. Immobilized GI and commercial GI both retained 90% of their activities under continuous flow after 180 mL of substrate solution passed through the column.

Made available in DSpace on 2014-12-17T14:07:02Z (GMT). No. of bitstreams: 1 JoseKMAR_DISSERT.pdf: 2948541 bytes, checksum: 646d8653b036843236db0bfc42c7f90b (MD5) Previous issue date: 2012-02-10 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Currently new polymeric materials have been developed to replace other of traditionally materials classes. The use of dyes allows to expand and to diversify the applications in the polymeric materials development. In this work the behavior and ability of azo dyes Disperse Blue 79 (DB79) and Disperse Red 73 (DR73) on poly(methyl methacrylate) (PMMA) were studied. Two types of mixtures were used in the production of masterbatches: 1) rheometer 2) solution. Processing by extrusion-blow molding of PMMA was carried out in order to evaluate the applications of polymeric films. Thermal analysis were performed by thermogravimetry to evaluate polymer and azo dyes thermal stability. Colorimetric analysis were obtained through monitoring the spectral variations associated with sys/trans/anti azo dyes isomerization process Colorimetric data were treated and evaluated in accordance to the color system RGB and CIEL*ab, by monitoring the color change as function of time. Mechanical properties, characterized by tensile tests, were evaluated and correlated with the presence and content of azo dyes in the samples. Analyses by scanning electronic microscopy (SEM) were performed on the surfaces of samples to check the azo dye dispersion after the mixing process. It was concluded that the production of PMMA/azo dyes is possible and feasible, and the mixtures produced had synergy of properties for use in various applications / Atualmente novos materiais polim?ricos v?m sendo desenvolvidos, visando substituir outras classes de materiais tradicionalmente empregados. O uso de corantes possibilita ampliar e diversificar as possibilidades de aplica??es no desenvolvimento desses novos materiais. Neste trabalho foi estudado o comportamento e a capacidade de tingimento dos azocorantes: Azul Disperso 79 (DB79) e o Vermelho Disperso 73 (DR73), em uma matriz de poli(metacrilato de metila) (PMMA). Duas formas de misturas foram utilizadas na produ??o dos concentrados: na primeira, em re?metro de torque e na segunda, em solu??o. O processamento por extrus?o-sopro do PMMA foi realizado neste trabalho com intuito de avaliar suas aplica??es na forma de filmes polim?ricos. An?lises t?rmicas foram realizadas por termogravimetria para avaliar a estabilidade t?rmica dos pol?meros e dos azocorantes. An?lises por colorimetria foram obtidas por meio do acompanhamento das mudan?as espectrais associadas ao processo de isomeriza??o cis/trans/anti dos azocorantes. Os dados de colorimetria foram tratados e avaliados segundo o sistema de cores RGB e CIEL*ab, por meio do acompanhamento da mudan?a de colora??o em fun??o do tempo. As propriedades mec?nicas, caracterizadas por meio de ensaios de tra??o uniaxial, foram avaliadas e correlacionadas com a presen?a e quantidade de azocorantes na constitui??o das amostras. An?lises por microscopia eletr?nica de varredura (MEV) foram realizadas nas superf?cies das amostras para verificar a dispers?o dos corantes no final do processo de mistura. Verificou-se que a produ??o de PMMA/azocorantes ? poss?vel e vi?vel e as misturas produzidas apresentaram sinergia de propriedades para utiliza??o em diversas aplica??es

Submitted by Kilvya Braga (kilvyabraga@hotmail.com) on 2018-04-19T14:53:27Z No. of bitstreams: 1 MARIAUGUSTA FERREIRA MOTA - TESE (PPGEQ) 2015.pdf: 7929755 bytes, checksum: 46b508fdcbc2c553fa37592a200d2ae5 (MD5) / Made available in DSpace on 2018-04-19T14:53:27Z (GMT). No. of bitstreams: 1 MARIAUGUSTA FERREIRA MOTA - TESE (PPGEQ) 2015.pdf: 7929755 bytes, checksum: 46b508fdcbc2c553fa37592a200d2ae5 (MD5) Previous issue date: 2015-02-27 / CNPq / Este trabalho de Tese descreve a preparação de argilas organofílicas a partir da argila Brasgel e Verde-Lodo naturais que foram utilizadas como cargas para síntese de nanocompósitos via polimerização in situ em suspensão e polimerização in situ em massa-suspensão. A caracterização para avaliar as argilas organofílicas foi realizada a partir das técnicas de Difração de raios X (DRX), Espectroscopia na Região do Infravermelho por Transformada de Fourier (IV) Análise Térmica Diferencial e Termogravimétrica (ATD/TG) e ensaios de expansão (Capacidade de Adsorção e Inchamento de Foster). A produção de nanocompósitos poli(pivalato de vinila)/argila foi realizada a partir da polimerização in situ em suspensão do pivalato de vinila utilizando 2,5% e 5% de argila Brasgel ou Verde-Lodo modificadas com os sais Praepagen, Dodigen e Genamin. O processo de obtenção do nanocompósito poli(metacrilato de metila)/argila foi realizada a partir da polimerização in situ em massa-suspensão do metacrilato de metila utilizando 3% de argilas Verde-Lodo natural ou modificadas com os sais Praepagen, Dodigen e mistura de sais (Praepagen + Dodigen). Os nanocompósitos polímero/argila foram caracterizados a partir de DRX, IV, TG, Microscopia Óptica (MO), Microscopia Eletrônica de Varredura (MEV) e Calorimetria Diferencial de Varredura (DSC). Os resultados de DRX mostram a intercalação dos sais quaternários de amônio (Praepagen, Dodigen e Genamin) em todas as argilas (Verde-Lodo e Brasgel) no processo de organofilização. Os resultados de IV e ATD indicam que os sais foram incorporados à estrutura da argila, evidenciando assim o processo de organofilização. Os testes de Capacidades de Adsorção comprovaram as melhores eficiências das argilas Verde-Lodo e Brasgel organofilizadas com os sais quaternários de amônio em relação às argilas na sua forma natural independente do solvente orgânico utilizado. Os resultados dos testes de Inchamentos de Foster indicaram que as afinidades dos sais ocorreram nas argilas organofílicas avaliadas em todos os solventes orgânicos. Os resultados obtidos de DRX a partir da polimerização in situ em suspensão do pivalato de vinila/argila Brasgel ou Verde-Lodo organofílicas indicaram interações argila-polímero na forma intercalada e esfoliada. As análises de TG indicaram que ocorreu diminuição no intervalo de 3oC a 10oC da temperatura máxima de degradação assim como a diminuição da Temperatura de transição vítrea (Tg) dos nanocompósitos contendo 2,5 e 5% de argila na matriz polimérica Poli(pivalato- vinila). Para os nanocompósitos sintetizados a partir do metacrilato de metila e da argila Verde-Lodo natural e organofilizadas os resultados de DSC a partir da polimerização in situ em massa-suspensão do metacrilato de metila/argila VerdeLodo natural e organofílicas indicaram que as temperaturas de transição vítrea não foram alteradas com a adição da argila. As análises de TG mostraram que houve alterações pouco significativas na temperatura máxima de degradação e as imagens de MEV indicaram que a morfologia dos nanocompósitos obtidos com 3% de argila Verde-Lodo organofilizadas apresentaram partículas esféricas e lisas, indicando interação da argila com a matriz polimérica. / This Doctorate Thesis describes the preparation of organoclays from raw clays Brasgel and Green-Sludge, which were used as charge materials to synthesis of nanocomposites via in situ suspension and in situ mass-suspension polymerization reactions. The organoclays characterization was carried out by making use of techniques of X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Differential Thermal Analysis and Thermogravimetric Analysis (DTA/TGA), and analysis of adsorption of organic compounds (Adsorption Capacity and Foster’s experiment). The synthesis of nanocomposites poly (vinyl pivalate)/clays were performed from in-situ suspension polymerization reaction of vinyl pivalate with 2.5% w. and 5% w. of organoclays Brasgel or Green-Sludge, in which were organophilized by using the quaternary ammonium salts Praepagen®, Dodigen®, and Genamin®. The synthesis of nanocomposites poly (methyl methacrylate)/clays were realized from in-situ mass-suspension polymerization reaction of methyl methacrylate with 3% w. of raw clay Green-Sludge or organoclay Green-Sludge organophilized by using the quaternary ammonium salts Praepagen®, Dodigen®, and the mixer of these surfactants (Praepagen® + Dodigen®). The nanocomposites polymer/clay were characterized with the techniques XRD, FTIR, TGA, Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Differential scanning calorimetry (DSC). The characterization results have shown the intercalation of the cations from the quaternary ammonium salts (Praepagen®, Dodigen®, and Genamin®) within the raw clays (Green-Sludge and Brasgel) after the organophilization reaction. The results of FTIR and DTA indicate that the cations of the surfactants were incorporated in the raw clays, in which it is related the organophilization process. The results of adsorption capacity of organic compounds show that the organoclays Green-Sludge and Brasgel compared with its respective raw clay form have higher adsorption of organic compounds for all compounds analyzed. The Foster’s experiment shows that all the organoclays synthetized have high affinity with organic molecules for all compounds analyzed. The results of XRD analysis from in-situ suspension polymerization of vinyl pivalate/Brasgel raw clay or organoclays Green-Sludge have shown the clay-polymer interactions in intercalated and exfoliated forms. From TGA analysis has been observed a decreasing of the maximum temperature of degradation between 3°C and 10°C, as well the decreasing of the glass transition temperature (Tg) for the nanocomposites with 2.5% w. and 5% w. of clay in the polymeric matrix poly (vynil pivalate). By analyzing the nanocomposites synthetized from methyl methacrylate and Green-Sludge raw clay or organoclays, the results of DSC have shown that the glass transition temperature does not change with the presence of clays. The TGA analysis has demonstrated the occurrence of small variations of the maximum temperature of degradation. The SEM results indicate that the morphology of the nanocomposites synthetized from 3% w. of organoclay GreenSludge has smooth and spherical particles, which indicates the interaction between the clay within the polymeric matrix.

Resumo: O objetivo deste estudo foi determinar a citotoxicidade in vitro de duas resinas reembasadoras experimentais autopolimerizáveis contendo alta concentração de agentes de ligação cruzada, etilenoglicol dimetacrilato (EGDMA) e 1,4-butanodiol dimetacrilato (BDMA) comparadas com uma resina reembasadora comercial (Tokuyama Rebase Fast II). Foram confeccionados corpos-de-prova em forma de discos das três resinas acrílicas reembasadoras rígidas sob condições assépticas. Os fibroblastos (L929) foram cultivados em placas com 96 compartimentos e incubadas por 24 h em meio de cultura Eagle. Os extratos foram preparados, colocando-se três amostras de cada resina em frascos de vidro estéreis com 9 mL de meio de Eagle e incubadas a 37º C por 24 h. O efeito citotóxico dos extratos foram avaliados utilizando os testes de incorporação do 3H-timidina e MTT, que refletem os níveis de síntese de DNA e metabolismo celular, respectivamente. Os dados foram analisados estatisticamente, utilizando análise de variância (P<0.05). Para o teste de incorporação do 3H-timidina, não foram observadas diferenças significativas (P>0.05) entre os materiais. A média da quantidade do isótopo incorporado no DNA celular para todas as resinas acrílicas foi estatisticamente menor do que para o controle. Todas as resinas acrílicas foram classificadas pelo teste de incorporação do 3Htimidina como moderadamente citotóxicas. Da mesma forma, para o teste do MTT, não foi encontrada diferença significativa para a citotoxicidade entre os materiais (P>0.05). Quando a citotoxidade foi comparado com o grupo controle, todas as resinas foram classificadas entre não citotóxicas e discretamente citotóxicas pelo teste do MTT. Assim, conclui-se que a incorporação dos agentes de ligação cruzada, EGDMA e BDMA não influenciaram significativamente sobre a citotoxicidade observada. Não houve diferença... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to determine the cytotoxicity in vitro of two trials autopolymerizing reline systems made with higher concentration of cross-linking agents, EGDMA and BDMA compared to a commercial reline resin. Sample disks of the three hard reline acrylic resins were fabricated under aseptic conditions. The Fibroblast L929 cells were cultured in 96-well plates and incubated for 24 h in Eagle's medium. Eluates were prepared by placing three samples into a sterile glass vial with 9 mL of Eagle's medium and incubating at 37ºC for 24 h. The cytotoxic effect from the eluates was evaluated using the 3H-thymidine incorporation and MTT assays, which reflect DNA synthesis levels and cell metabolism, respectively. The data were statistically analyzed by using the one-way analysis of variance (P<.05). With the 3H-thymidine incorporation assay, no significant differences (P > .05) were found between the materials. The mean quantity of isotope incorporated into cellular DNA for all acrylic resins was statistically smaller than for the control. All acrylic resins were graded by the 3Hthymidine incorporation assay as moderate cytotoxic. Similarly, with the MTT assay, no significant difference in cytotoxicity was found between the materials (P > .05). When the cytotoxicity was compared with control group, all resins assay were between non cytotoxic and slight cytotoxic by the MTT. The incorporation of cross-linking agents, EGDMA and BDMA had no significant influence on the cytotoxicity observed. There was no cell viability difference between all materials in both assays. / Orientador: Eunice Teresinha Giampaolo / Coorientador: Iracilda Zeppone Carlos / Banca: Renata Cristina Silveira Rodrigues Ferracioli / Banca: Iracilda Zeppone Carlos / Mestre

O objetivo deste trabalho foi avaliar a influência de diferentes aminas terciárias no grau de conversão, na contração de polimerização, na taxa de contração, na microdureza Knoop, na estabilidade de cor e na transmitância de luz de resinas experimentais, contendo, em peso, BisGMA e TEGDMA (3:1), 0,25% de canforquinona (CQ) e 1% de amina (DMAEMA, CEMA, DMPT, DEPT ou DABE). A influência de diferentes protocolos de fotoativação também foi investigada. O grau de conversão foi avaliado através de FTIR-ATR e a contração pelo método do disco aderido. A partir da diferenciação numérica dos dados de contração em relação ao tempo, obteve-se a taxa de contração de polimerização. A estabilidade de cor e a transmitância foram avaliadas em diferentes períodos de envelhecimento artificial. Os resultados foram avaliados pelos testes de ANOVA, Tukey e T3 de Dunnett (&#945; = 0,05). As propriedades estudadas variaram em função da amina. O grau de conversão e a contração de polimerização variaram na sequência: CQ < DEPT < DMPT &#8804; CEMA &#8776; DABE < DMAEMA. O grau de conversão e a contração também foram influenciados pelo protocolo de fotoativação, sendo observadas correlações positivas entre o grau de conversão e a contração e entre o grau de conversão e a taxa de contração. A cor variou na sequência: DMAEMA < DEPT < DMPT < CEMA < DABE. A transmitância variou na sequência: DEPT &#8776; DABE < DABE &#8776; DMPT &#8776; CEMA < DMPT &#8776; CEMA &#8776; DMAEMA, sendo mais evidente para o comprimento de onda de 400nm. Não foram observadas correlações entre o grau de conversão e as propriedades ópticas. A resina contendo DMAEMA apresentou maior grau de conversão, contração, taxa de contração e dureza, além de melhor estabilidade nas propriedades ópticas. / The aim of this work was to evaluate de influence of different tertiary amines on degree of conversion (DC), shrinkage-strain, shrinkage-strain-rate, Knoop microhardness, and colour and transmittance stabilities of experimental resins containing BisGMA / TEGDMA (3:1 wt), 0,25wt% camphorquinone, 1wt% amine (DMAEMA, CEMA, DMPT, or DABE). Different light-curing protocols were also evaluated. DC was evaluated with FTIR-ATR and shrinkage-strain with the bonded-disc method. Shrinkage-strain-rate data were obtained from numerical differentiation of shrinkage-strain data with respect to time. Colour stability and transmittance were evaluated during different periods of artificial aging, according to ISO 7491:2000. Results were evaluated with ANOVA, Tukey and Dunnetts T3 tests (&#945; = 0.05). The studied properties varied according to amines. DC and shrinkage-strain were maximum at the sequence: CQ < DEPT < DMPT &#8804; CEMA &#8776; DABE < DMAEMA. Both DC and shrinkage were also influenced by the curing protocol, with positive correlations between DC and shrinkage-strain and DC and shrinkage-strain-rate. Colour varied in the sequence: DMAEMA < DEPT < DMPT < CEMA < DABE. Transmittance varied in the sequence: DEPT &#8776; DABE < DABE &#8776; DMPT &#8776; CEMA < DMPT &#8776; CEMA &#8776; DMAEMA, being more evident at the wavelength of 400nm. No correlations between DC and optical properties were observed. The resin containing DMAEMA showed higher DC, shrinkage-strain, shrinkage-strain-rate and microhardness, in addition with better optical properties.

A exploração não racional dos recursos florestais nativos, no Brasil, tem provocado a redução da oferta de espécies de uso consagrado em diversos segmentos, notadamente na construção civil e na indústria de móveis. A alternativa mais imediata tem sido o emprego da madeira de reflorestamento, em particular, dos gêneros Eucalyptus e Pinus, freqüentes nas regiões sul e sudeste do país. Porém, muitas das espécies disponíveis comercialmente não apresentam propriedades fisico-mecânicas que as tornem capazes de promover a substituição das espécies tradicionalmente empregadas. Neste contexto, o presente trabalho tem como objetivo demonstrar a viabilidade de se obterem compósitos polímero-madeira (CPMs) que podem apresentar comportamento equivalente ou superior ao da madeira sem tratamento, proveniente das regiões de reflorestamento dos mencionados gêneros. Para tal, foi feita a impregnação da madeira das espécies Eucalyptus grandis e Pinus caribaea var. hondurensis por apresentarem maior disponibilidade e densidade compatível para viabilizar o processo. Empregaram-se os monômeros poliméricos de estireno e metacrilato de metila e, como iniciador no processo de polimerização, o peróxido de benzoíla. Foi utilizado o método de vácuo-pressão para a impregnação da solução monômero-iniciador. Os resultados mostraram, para os CPMs de Pinus, um significativo aumento nos valores de todas as propriedades estudadas. Nos CPMs de Eucalyptus, em decorrência de sua baixa permeabilidade, somente os valores das durezas paralela e normal às fibras apresentaram aumento. / Large exploration of native forestry resources in Brazil has led to a decrease in supply of the most widely used species in several sectors, notably in civil construction and furniture industries. The most immediate remedy has been the use of reforestation timber, obtained from the common Eucalyptus and Pinus species available in the south and southwest regions of the country. However, most of these species do not present adequate physical and mechanical properties to viably the mentioned uses. In this context, the main objective of the present research is to demonstrate the viability of obtaining wood-polymer composites (WPCs), which may exhibit similar or superior physical and mechanical properties than untreated aforementioned species from reforestation regions of Brazil. In order to achieve this goal, the impregnation of Eucalyptus grandis and Pinus caribaea var. hondurensis, which have compatible density and are available in large amounts to permit such processing, was carried out. In the process, polymeric monomers of styrene and methyl methacrylate were employed with benzyl peroxide, whose functions as an initiator in the polymerization process. Vacuum-pressure method was used in the impregnation of the monomer-initiator solution. Properties of the WPCs – Pinus were significantly improved in all tests, however, because of its low permeability, only hardness parallel and perpendicular to grain showed increase for the WPCs – Eucaliptus.