O efeito do tratamento da atapulgita no desenvolvimento de compósito com o polietileno reciclado

The study aimed at the treatment of attapulgite for the development and characterization of composite recycled low density polyethylene - PEBD_rec embedded with natural attapulgite - ATP_NAT, sifted - ATP_PN and attapulgite treated with sulfuric acid - ATP_TR in different compositions (1, 3 and 5%) and compared with the PEBD_rec. The atapulgitas, natural, screened and treated, were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and determining the area specific surface (BET). The composites were characterized by thermogravimetry (TG), differential scanning calorimetry (DSC), Xray diffraction (XRD), torque rheometry, scanning electron microscopy (SEM) and traction. The composite PEBD_rec / ATP (natural, sieved and treated) were produced by mixing in the molten state in a single screw extruder matrix wire with subsequent reprocessing matrix tape. It was found that the screening of attapulgite not reduce the quantity of quartz and the acid treatment completely extracted dolomite aggregate impurities of the channels attapulgite, and increase their surface area. The addition of attapulgite in PEBD_rec acts as a catalyst, reducing the thermal stability of the polymer. The increased concentration of attapulgite, increases resistance and reduces the elongation at break and modulus of elasticity of the composite PEBD_rec / attapulgite

Método de derivación e integración de orden arbitrario en el modelado mecánico y dieléctrico de materiales poliméricos

En este trabajo se presenta el desarrollo de un Modelo Fraccional Mecánico y un Modelo Fraccional Dieléctrico, con la finalidad de describir las manifestaciones mecánicas y dieléctricas de la viscolesticidad de un polímero semicristalino (PEN) que presenta 3 fenómenos de relajación.

Tratamentos de fibras de carnaúba [copernicia prunífera (miller) h. e. moore] para o desenvolvimento de compósito biodegradável com matriz de polihidroxibutirato

The use of raw materials from renewable sources for production of materials has been the subject of several studies and researches, because of its potential to substitute petrochemical-based materials. The addition of natural fibers to polymers represents an alternative in the partial or total replacement of glass fibers in composites. In this work, carnauba leaf fibers were used in the production of biodegradable composites with polyhydroxybutyrate (PHB) matrix. To improve the interfacial properties fiber / matrix were studied four chemical treatments to the fibers..The effect of the different chemical treatments on the morphological, physical, chemical and mechanical properties of the fibers and composites were investigated by scanning electron microscopy (SEM), infrared spectroscopy, X-ray diffraction, tensile and flexural tests, dynamic mechanical analysis (DMA), thermogravimetry (TGA) and diferential scanning calorimetry (DSC). The results of tensile tests indicated an increase in tensile strength of the composites after the chemical treatment of the fibers, with best results for the hydrogen peroxide treated fibers, even though the tensile strength of fibers was slightly reduced. This suggests a better interaction fiber/matrix which was also observed by SEM fractographs. The glass transition temperature (Tg) was reduced for all composites compared to the pure polymer which can be attributed to the absorption of solvents, moisture and other low molecular weight molecules by the fibers

Processamento e caracterização de compósitos Poli(METACRILATO DE METILA)/Sílica (PMMA/SiO2)

Currently the search for new materials with properties suitable for specific applications has increased the number of researches that aim to address market needs. The poly (methyl methacrylate) (PMMA) is one of the most important polymers of the family of polyacrylates and polymethacrylates, especially for its unique optical properties and weathering resistance, and exceptional hardness and gloss. The development of polymer composites by the addition of inorganic fillers to the PMMA matrix increases the potential use of this polymer in various fields of application. The most commonly used inorganic fillers are particles of silica (SiO2), modified clays, graphite and carbon nanotubes. The main objective of this work is the development of PMMA/SiO2 composites at different concentrations of SiO2, for new applications as engineering plastics. The composites were produced by extrusion of tubular film, and obtained via solution for application to commercial PMMA plates, and also by injection molding, for improved the abrasion and scratch resistance of PMMA without compromising transparency. The effects of the addition of silica particles in the polymer matrix properties were evaluated by the maximum tensile strength, hardness, abrasion and scratch resistance, in addition to preliminary characterization by torque rheometry and melt flow rate. The results indicated that it is possible to use silica particles in a PMMA matrix, and a higher silica concentration produced an increase of the abrasion and scratch resistance, hardness, and reduced tensile strength

Hematina como catalizador biomimético en la síntesis de polianilina conductora.

El propósito de este trabajo fue la polimerización de la anilina utilizando la hematina como catalizador biomimético en un medio de reacción ácido utilizando como disolvente el ácido acético, lo cual permitió realizar la síntesis de polianilina sin la necesidad de usar “plantillas” las cuales afectan las propiedades electroquímicas del producto final. El polímero sintetizado mediante esta técnica mostró buenas características estructurales tal y como lo demostraron los espectros de FTIR y UV-Vis. Además de contar con una buena cristalinidad y estabilidad térmica, como se pudo constatar en las pruebas de DRX y TGA respectivamente. La conductividad eléctrica, la electroactividad y la reversibilidad oxidativa de la polianilina sintetizada fueron bastante aceptables considerando las condiciones de síntesis. Finalmente el proceso de optimización de la reacción llevó a rendimientos de hasta 70%.

Development of Locust Bean Gum Nanoparticles for protein delivery

Dissertação de Mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2014

Evaluación antimicrobiana de rifampicina nanoencapsulada contra aggregatibacter actinomycetemcomitans presente en la periodontitis

Introducción. A pesar de los esfuerzos tanto de la medicina como de la industria farmacéutica, el incremento en la prevalencia de resistencia en bacterias patógenas frente a antibióticos se ha vuelto uno de los mayores problemas en la medicina moderna. El área odontológica tampoco se encuentra exenta, siendo común el uso excesivo de antibióticos lo que contribuye al desarrollo de resistencia antimicrobiana. La primera etapa para el desarrollo de la enfermedad periodontal es la formación de un biofilm de bacterias periodontopatógenas, siendo el Aggregaribacter actinomycetemcomitans (A.a) uno de los más asociados a dicha enfermedad. El tratamiento de esta patología se basa en remover mecánicamente la placa dentobacteriana y, en segunda instancia, en el apoyo de terapia antimicrobiana para coadyuvar la eliminación de las bacterias periodontopatógenas, cuales tienen gran similitud con Mycobacterium tuberculosis. La rifampicina es uno de los antibióticos efectivos contra bacterias multi-resistentes y la primera elección en el tratamiento de tuberculosis activa. Con el fin de mejorar la terapia farmacológica y evadir la resistencia del agente infectivo, se han propuesto nuevas estrategias basadas en sistemas de liberación controlada. Entre los más estudiados en los últimos 10 años se encuentran las nanopartículas poliméricas. El objetivo del presente estudio fue evaluar la actividad antimicrobiana de la rifampicina nanoencapsulada contra el A.a presente en la periodontitis. Materiales y Métodos. Para el estudio, Se tomaron muestras de fluido crevicular en pacientes con bolsas periodontales de 5-10 mm de profundidad. Se inoculo caldo de tripticaseina de soya (TCS) con las muestras tomadas y se incubaron a 37 ° C en condiciones aeróbicas por 7 días. La presencia de Aggregatibacter actinomycetemcomitans (A.a) fue determinado mediante PCR en tiempo real. La Concentración Mínima Inhibitoria (MIC) de rifampicina para interferir con el crecimiento de bacterias orales fue determinada mediante la técnica de dilución de tubos. Posteriormente se prepararon mediante la técnica de nanoprecipitación NP de Eudragit® EPO, L100-55 y PLA entre 100 y 200 nm y su IP con distribución de tamaño homogéneo. Resultados. A.a fue detectado en muestras de fluido crevicular en pacientes con periodontitis, corroborando su asociación con dicha patología. La efectividad de la rifampicina libre contra bacterias orales fue confirmada, obteniéndose una CMI de 1 µg/ml. Las NP con Rifampicina se ajustaron a la misma CMI que la Rif libre. Las NP de Eudragit® EPO cargadas con Rif mostraron que la liberación de la Rif de la NP fue inmediata, mientras que el Eudragit® L100-55 y PLA con Rif no mostró inhibición durante los 5 días de incubación. Esto hace suponer que el fármaco no fue liberado o solo se liberó en una baja proporción que no permitió llegar a la CMI. Conclusión. La rifampicina es una excelente alternativa terapéutica para el tratamiento de la enfermedad periodontal, promoviendo resultados favorables en la evaluación clínica de pacientes. Sería interesante continuar con estudios utilizando otro polímero o mezcla de ellos para favorecer la liberación del fármaco en la NP.

Establishment of a protocol for the cryopreservation of cell sheets of adipose tissue stem cells

Dissertação de Mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2016

Efeito da adição de grafite expandido por microondas nas propriedades térmicas, elétricas e mecânicas de nanocompósitos de matriz epóxi

Epoxy based nanocomposites with 1 wt % and 3 wt % of nanographite were processed by high shear mixing. The nanographite was obtained by chemical (acid intercalation), thermal (microwave expansion) and mechanical (ultrasonic exfoliation) treatments. The mechanical, electrical and thermal behavior of the nanocomposites was determined and evaluated as a function of the percentage of reinforcement. According to the experimental results, the electrical conductivity of epoxy was not altered by the addition of nanographite in the contents evaluated. However, based on the mechanical tests, nanocomposites with addition of 1 wt.% and 3 wt.% of nanographite showed increase in tensile strength of 16,62 % and 3,20 %, respectively, compared to the neat polymer. The smaller increase in mechanical strength of the nanocomposite with 3 wt.% of nanographite was related to the formation of agglomerates. The addition of 1 wt.% and 3 wt.% of nanographite also resulted in a decrease of 6,25 % and 17,60 %, respectively, in the relative density of the material. Thus, the specific strength of the nanocomposites was approximately 33,33 % greater when compared to the neat polymer. The addition of 1 wt.% and 3 wt.% of nanographite in the material increased the mean values of thermal conductivity in 28,33 % and 132,62 %, respectively, combined with a reduction of 26,11 % and 49,80 % in volumetric thermal capacity, respectively. In summary, it has been determined that an addition of nanographite of the order of 1 wt.% and 3 wt.% produced notable elevations in specific strength and thermal conductivity of epoxy

Síntese do Poli (ácido láctico) por policondensação direta utilizando um planejamento fatorial

The environmental impact caused by the disposal of non-biodegradable polymer packaging on the environment, as well as the high price and scarcity of oil, caused increase of searches in the area of biodegradable polymers from renewable resources were developed. The poly (lactic acid) (PLA) is a promising polymer in the market, with a large availability of raw material for the production of its monomer, as well as good processability. The aimed of this study was synthesis PLA by direct polycondesation of lactic acid, using the tool of experimental design (DOE) (central composite rotatable design (CCRD)) to optimize the conditions of synthesis. The polymer obtained was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), viscosimetric analysis, differential scanning calorimeter (DSC) and size exclusion chromatography (SEC). The results confirmed the formation of a poly (lactic acid) semicrystalline in the syntheses performed. Through the central composite rotatable design was possible to optimize the crystallization temperature (Tc) and crystallinity degree (Xc). The crystallization temperature maximum was found for percentage of catalyst around the central point (0,3 (%W)) and values of time ranging from the central point (6h) to the upper level (+1) (8h). The crystallization temperature maximum was found for the total synthesis time of 4h (-1) and percentage of catalyst 0,1(W%) (-1). The results of size exclusion chromatography (SEC) showed higher molecular weights to 0,3 (W%) percent of catalyst and total time synthesis of 3,2h

Adição de poliuretana em pastas de cimento para poços de petróleo como agente de correção do filtrado

Chemical admixtures, when properly selected and quantified, play an important role in obtaining adequate slurry systems for quality primary cementing operations. They assure the proper operation of a well and reduce costs attributed to corrective cementing jobs. Controlling the amount lost by filtering through the slurry to permeable areas is one of the most important requirements in an operation, commonly controlled by chemical admixtures, such as carboxymethylcellulose (CMC). However, problems related to temperature, salttolerance and the secundary retarding effect are commonly reported in the literature. According to the scenario described above, the use of an aqueous dispersion of non-ionic poliurethane was proposed to control the filter loss, given its low ionic interaction with the free ions present in the slurries in humid state. Therefore, this study aims at assessing the efficiency of poliurethane to reduce filter loss in different temperature and pressure conditions as well as the synergistic effect with other admixtures. The temperatures and pressures used in laboratory tests simulate the same conditions of oil wells with depths of 500 to 1200 m. The poliurethane showed resistance to thermal degradation and stability in the presence of salts. With the increase in the concentration of the polymer there was a considerable decrease in the volume lost by filtration, and this has been effective even with the increase in temperature

Caracterização reológica de pastas de cimento portland de alta resistência contendo diferentes tipos de polímeros superabsorventes pela técnica de reometria rotacional

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2016.

Synthesis and characterization of low-cost materials for aqueous Na-ion batteries

136 p.

Diseño de un vector no viral basado en nanopartículas lipídicas para el tratamiento de la hepatitis C mediante ARN de interferencia

199 p.

Fouling in emulsion polymerization reactors

160 p.