Influência da incorporação de nanofibras de poliamida 6 com e sem nanotubos de carbono como reforço de prótese parcial fixa adesiva

The aim of this study was to evaluate the behavior of reinforced composites with polyamide 6 fibers aligned (6000 rpm) and alignment (120 rpm) with or without CNT using the flexural strength test. After preparation of nanofibers aligned nylon 6 (6000 rpm) and alignment (120 rpm) with and without incorporation of nanotube carbon by the method of electrospinning, were performed one control group (n = 10) and 4 experimental groups (n = 40) G1: Control (just resin Charisma - Heraeus Kulzer) ;G2 Resin + N6 aligned (6000 rpm) + CNT; G3:Resin + N6 alignment (120 rpm) + CNT; G4: Resin + aligned ( 6000 rpm) N6. G5: Resin + N6 alignment (120 rpm). The fibers were cut to the dimensions of 0,3 x 15 mm and were applied an adhesive at the surface (Single Bond 2) for 5 min and cured. In the matrix, was added resin in the proximal box (Charisma A2, Heraeus Kulzer) and cured for 40 s. (power 1100 mW / cm²). A first layer of resin and on the resin was deposited. The resin layers specimens were light irradiated with three overlapping exposures delivered. For each resin layer were light irradiated for 40 sec. The samples were tested with a cross-speed of 1 mm / min, and a 50 Kgf at Universal testing machine (EMIC mod.DL2000). The Dunnet test showed that only the nanotube group was significantly different from the control group. The ANOVA two-way indicates that the nanotube factor was statistically significant (p < 0.05) and there is no interaction between factors and orientation nanotube. The presence of nanotube showed lower fracture resistance values for aligned and unaligned groups. The results of this study showed that the orientation of the fibers does not influence the strength of composite resins and the incorporation of nylon nanofibers with carbon nanotubes decreased the fracture resistance values. The presence of the fibers has not been able to improve the strength of the material in any of the...

Aplicação de carbono vítreo monolítico para produção de eletrodos a partir da resina furfurílica com diferentes variações de pH

Nowadays, we live in a time of rapid research for technological advances, in a way that this pursuit of new technologies is deeply connected to the diversity of new materials that have been developed by mankind. It deals with issues such as materials with enhanced properties which offer better quality, less cost and high performance, while they are accessible both in their production and moment of operation. In this context, it was required to develop electrodes that were easy to prepare as well as which present high electric conductivity and good mechanic proprieties by using carbonaceous material as basis. For this reason, the best parameters of the furfuryl resin cures were established with different pH variations through viscosimetric measurements and differential scanning calorimetry. By scanning electron microscopy (SEM) was possible to identify an increased porosity in the samples with pH 7 and pH 8, as compared to samples with lower pH content. After carbonization of the material, the characterization of monolithic glassy carbon was held by means of FT-IR techniques, Raman spectroscopy, X-ray diffraction and cyclic voltammetry. The spectra showed that the change in pH does not have significant influence on the crystallographic ordering of the material and its structural characteristics. As for the electrochemical character, the CVM electrodes showed excellent response, with good reversibility and wide potential window. Some voltammetric curve deviations were only observed for the sample with pH 4, which may be related to processing parameters adopted

Avaliação imediata e após 6 meses da resistência de união a dentina de restaurações de resina composta classe I in vivo e in vitro

Pós-graduação em Odontologia Restauradora - ICT

Biocompatibilidade de resinas acrílicas para base e reembasamento de próteses após períodos de imersão em soluções desinfetantes: análise do metabolismo celular

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito do gradiente interior-borda-matriz, e do tipo de matriz sobre a entomofaúna edáfica em fragmentos de cerrado

edge effect. Thus, under the influence of the adjacent matrix, fragments undergo microclimatic alterations that accentuate changes in species composition and community structure. In order to better understand edge and matrix effects on the richness and abundance of edaphic arthropods, this study assessed: (a) the difference between habitat (fragment) and non-habitat (matrix); (b) whether there is a continuous interior-edge-matrix gradient; and (c) the difference between matrices for arthropod orders richness and abundance. We selected 15 landscapes, 5 of which contained a cerrado fragment surrounded by sugarcane cultivation, 5 with a cerrado fragment within eucalyptus and 5 with a cerrado fragment within pasture. In each landscape the soil fauna was collected along with the soil and then extracted with the aid of the modified Berlese-Tullgren funnel. We chose the orders Coleoptera, Collembola, Mesostigmata and Oribatida for analysis, and after separation of the individuals we used model selection analysis via AIC. The model type fragment x matrix was the most likely to explain richness, total and relative abundances of the four orders (wAICc between 0,6623 and 1,0). The model of edge distance (edge effect) was plausible to total abundance and relative abundance of Mesostigmata order (wAICc=0,2717 and 0,186). Local environmental variables (soil texture, temperature and relative humidity), and fragment size were also measured to avoid confounding factors and were not presented as plausible models to explain the patterns. So edaphic arthropods, despite protecting themselves under the ground, are extremely sensitive to fragmentation, even with the replacement of natural habitat by agricultural use, such as sugarcane, pasture and eucalyptus. This group should be studied environmental impact assessments because provides important ecosystem se ravincde s inacnludd eisd ainn efficient bio-indicator

Estudo da cinética de degradação da resina benzoxazina e seus compósitos nanoestruturados

The benzoxaxine resin is a new class of thermoset phenolic resin, which is presenting, in the lasts decades, a great application in the aircraft industry due mainly to its excellent mechanical and thermal properties. This resin associates the mechanical properties of epoxy resin with the thermal and flame retardant properties of phenolic resin. In this context, they are considered polymers of high performance and they are excellent candidates to replace the current thermoset matrices used in the processing of high performance composites. Thus, in this study nanostructured composites Benzoxazine/CNT were produced at different concentrations of functionalized and non-functionalized CNT (0,1%; 0,5% and 1,0% w/w). The thermal stability of the benzoxazine resin and its nanostructured composites was studied using thermogravimetry (TGA) and degradation kinetic model Ozawa-Wall-Flynn (O-W-F). The thermal characterization also included differential scanning calorimetry (DSC) and dynamic-mechanical analysis, infrared spectroscopy with Fourier transform (FTIR) and scanning electron microscopy (SEM).The introduction of non-functionalized CNT at low concentrations resulted in nanostructured composites with better thermal properties in relation to the neat resin. For all cases, however, the dispersion of CNT in the matrix was ineffective

Aplicação de polímero hidroretentor no desenvolvimento inicial de Eucalyptus grandis

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Influência do comprimento do parafuso nas propriedades biomecânicas da placa de reconstrução bloqueada

Pós-graduação em Biotecnologia Animal - FMVZ