Comportamento térmico, mecânico e morfológico dos compósitos de polietileno de alta densidade reforçados com fibras de celulose do bagaço de cana de açucar

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Resin composite characterizations following a simplified protocol of accelerated aging as a function of the expiration date

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Properties of Mortar Using Cubes, Prism Halves, and Cylinder Specimens

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Processamento e caracterização de compósito fibra de sisal/resina epóxi via RTM

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da adição de nanopartículas na estabilidade de cor, microdureza e resistência à flexão de resina específica para confecção de próteses oculares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Processamento do compósito de fibra de capim-sapê / epóxi e avaliação da resistência à flexão “t” de Student

In recent years a great worldwide interest has arisen for the development of new technologies that enable the use of products with less environmental impact. The replacement of synthetic fiber plants is a possibility very important because this fiber is renewable, biodegradable and few cost and cause less environmental impact. Given the above, this work proposes to develop polymeric composites of epoxy resin and study the behavior of these materials. Both, the epoxy resin used as matrix in the manufacture of sapegrass fiber composite, as tree composites formed by: epoxy/unidirectional sapegrass long fiber, 75% epoxy/25% short fiber, by volume, and 80% epoxy/20% short fiber, by volume, were characterized by bending, and the composites produced with short fibers random were inspected by Optical Microscopy and Acoustics Inspection (C-Scan). For the analysis of the sapegrass fiber morphology, composites 75% epoxy/25% short fiber (sheet chopped) and 80% epoxy/20% short fiber images were obtained by optical microscope and the adhesion between polymer/fiber was visualized. As results, the flexural strength of composites epoxy/unidirectional long fibers, 75% epoxy/25% short fiber and 80% epoxy/20% short fiber were 70.36 MPa, 21.26 MPa, 25.07 MPa, respectively. Being that composite showed that the best results was made up of long fibers, because it had a value of higher flexural strength than other composites analyzed

Reciclagem de poliestireno expandido: compósito com fibras de algodão para a confecção de placas de circuito impresso

In this work polymeric composites reinforced with cotton fibers, from the textile industry, were developed in order to manufacture printed circuit boards. It was used expanded polystyrene (EPS) as a thermoplastic matrix by melting it. For the obtention of 10% and 15% of fiber volume fraction in cotton fibers composites, it was used wasted cotton fibers as an incentive of recycling and reusing of the domestic and industrial wastes as well as for Expanded Polystyrene(EPS). The mechanical properties of the composites were evaluated by tensile and flexural strength from standardized test methods. Composites were characterized by a Scanning Electron Microscopy (SEM), Thermogravimetry (TG/DTG), Differential Scanning Calorimetry (DSC) and dielectric analysis. The analysis of the results showed that fiber in the composite directly influenced in the thermal and mechanical properties

Efeito do tratamento alcalino da fibra na resistência mecânica do compósito epóxi/capim-sapê

Due to growing concerns for reducing environmental damage caused by the use of non-renewable raw materials, there is a growing demand for research related to aggregate technology with environmental preservation. Thus, the use of non-renewable materials and less aggressive materials has been gaining attention. About composite materials, the exchange of synthetic fibers by natural fibers, especially vegetable fiber as reinforcement, has been increasing, due to its physical-chemical properties such as mechanical strength, nontoxic, low cost, low density, processing flexibility, non-abrasive to the process equipment, requiring simple surface treatments, etc. This objective was to process composites reinforced with long fibers of sapegrass in epoxy matrix and characterize the composites through mechanical tests. Three groups of composites were prepared according to the treatment received by the reinforcement: without treatment, alkali treatment at concentration of 5% w/v and alkali treatment at 10% w/v concentration. The materials were analyzed by tensile and flexural, and tests also optical microscopy and scanning electron microscopy (SEM). The results were statistically analyzed. As the main result, the alkali treatment of 5% in the sapegrass fibers increases the tensile and flexural strength, as a consequence of the improve adhesion between matrix and reinforcement

Obtenção de rochas sintéticas a partir de resíduos de vidro comercial e pó de granito

Pós-graduação em Engenharia Mecânica - FEG

Resistência à flexão em porcelana feldspática: efeito da ciclagem mecânica e limite de fadiga pelo método escada

This study evaluated the fatigue limit (FL) by the staircase method and the effect of mechanical cycling on the flexural strength (FS) of Duceragold feldspathic porcelain. Specimens (25 x 5 x 2 mm) were made according to manufacturer’s directions and submitted to three-point flexural strength test (n = 10). To determine FL (n = 30; 10,000 cycles; 2 Hz), an initial loading of 60% of the FS and an incremental loading (step) of 3% of the FS were used. Data were analyzed by Anova and Tukey´s test (p < 0.05). Although the proposed cycles have not reduced FS significantly, fractography analysis showed striation, characteristic signs of mechanical fatigue.

Caracterização química e resistência à flexão de uma resina acrílica após a incorporação de um polímero com atividade antimicrobiana

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito das dimensões dos corpos de prova na resistência à flexão de compósitos restauradores

The aim of this study was to evaluate the influence of specimen size, in comparison with the ISO Standard, on the three point flexural strength of resin composite restorative materials Filtek Supreme and Filtek Z-250. Forty specimens were fabricated for each material with the following length, width and thickness measurements (n = 10): 1) 20 × 2 × 2 mm (ISO 4049); 2) 10 × 2 × 1 mm; 3) 10 × 1 × 1 mm; 4) 8 × 0.8 × 0.8 mm. The composites were inserted in a single increment into two-piece metal device and light-polymerized. The specimens were dry stored at 37 ± 1 °C and protected from light for 7 days. After this period, flexural strength was measured by three-point flexure test using MTS 810 equipment, with a load cell of 10 kN at a speed of 0.5 mm/min. For the evaluated sizes, the results showed significant variability (p = 0.00) with values when compared with the ISO Standard (116.700 MPa), being statistically higher for the test specimens measuring 10 × 1 × 1 mm (142.530 MPa), similar for those of 10  ×  2  ×  1  mm (115.815 MPa) and lower for those of 8 × 0.8 × 0.8 mm (86.650 MPa). There was statistical equality (p = 0.08) for the studied composites (Filtek Supreme, 125.270 MPa; Filtek Z-250, 108.130 MPa). Specimens measuring 10 × 2 × 1 mm provided flexural strength values equivalent to those obtained in the sizes recommended by the ISO 4049 standard, with lower consumption of material, energy and time.

Resistência à flexão de uma resina acrílica após a incorporação de um polímero antimicrobiano

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da resistência à fratura de próteses fixas temporárias reforçadas por uma malha experimental

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito da água ozonizada e gluconato de clorexidina sobre propriedades mecânicas e microbiológicas de materiais utilizados para confecção de próteses odontológicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)