A split-mouth randomized clinical trial of conventional and heavy flowable composites in class II restorations

Objective: The aim of this study was to evaluate the 2-year clinical performance of class II restorations made with a composite resin with two different viscosities.Methods: 47 patients received two class II restorations (n = 94), one made with GrandioSO (conventional viscosity CV), and the other with GrandioSO Heavy Flow (flowable viscosity FV), subjecting both materials to the same clinical conditions. The self-etching adhesive Futurabond M was used for all restorations. The composites were inserted using the incremental technique. The restorations were evaluated using the modified USPHS criteria according to the periods: baseline, 6 months, 1 year and 2 years after restorative procedures.Results: After 24 months, 40 patients attended the recall and 78 restorations were evaluated. In all periods, no secondary caries was observed. After 6 months, there were slightly overall changes of scores for most parameters. After 24 months, the higher number of changes from score Alfa to Bravo was observed for marginal discolouration (32.5% CV and 39.5% FV) and colour match (15% CV and 31.6% FV), followed by proximal contact (25% CV and 23.7% FV) and marginal adaptation (20% CV and 21.1% FV). For wear, surface texture and postoperative sensitivity the changes were very small. Just two restorations were lost during the 24-month follow up. Less than 5% of all restorations showed postoperative sensitivity. Chi-square test showed no significant differences between the two materials for all parameters analysed.Conclusion: After 2 years of clinical service, no significant differences were observed between GrandioSO conventional and GrandioSO Heavy Flow for the parameters analysed. Both materials provided acceptable clinical behaviour in class II restorations. Clinical Significance: This study presents the possibility of using a flowable composite with high filler content, for performing class II restorations. (C) 2014 Elsevier Ltd. All rights reserved.

Enhanced photoabsorption properties of composites of Ti/TiO2 nanotubes decorated by Sb2S3 and improvement of degradation of hair dye

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Benzoxazine Resin/Carbon Nanotube Nanostructured Composite's Degradation Kinetic

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Environmental effects on viscoelastic behavior of carbon fiber/PEKK thermoplastic composites

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sugarcane bagasse cellulose fibres and their hydrous niobium phosphate composites: synthesis and characterization by XPS, XRD and SEM

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Radiant exposure effects on physical properties of methacrylate - and silorane-composites

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Investigation of the dielectric relaxation processes in PbZr0.65Ti0.35O3-BaFe12O19 multiferroic ceramic composites

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Processing and characterization of ablative composites used in rocket motors

The main objective of this research work was to obtain two formulations of ablative composites. These composites are also known as ablative structural composites, for applications in atmospherically severe conditions according to the high-temperature, hot gaseous products flow generated from the burning of solid propellants. The formulations were manufactured with phenolic resin reinforced with chopped carbon fiber. The composites were obtained by the hot compression molding technique. Another purpose of this work was to conduct the physical and chemical characterization of the matrix, the reinforcements and the composites. After the characterization, a nozzle divergent of each formulation was manufactured and its performance was evaluated through the rocket motor static firing test. According to the results found in this work, it was possible to observe through the characterization of the raw materials that phenolic resins showed peculiarities in their properties that differentiate one from the other, but did not exhibit significant differences in performance as a composite material for use in ablation conditions. Both composites showed good performance for use in thermal protection, confirmed by firing static tests (rocket motor). Composites made with phenolic resin and chopped carbon fiber showed that it is a material with excellent resistance to ablation process. This composite can be used to produce nozzle parts with complex geometry or shapes and low manufacturing cost.

Comparação de compósitos obtidos via RTM de resina epóxi e fibra de carbono com e sem descontinuidade nos tecidos

Technology is growing interest in the use of composites, due to the requirement of lighter materials and more resistant, factors essential to meet the project specifications and reduce the operational cost. In the production of high performance structural composites, considering the aerospace criteria, the domestic industry has shown interest in the process of resin transfer molding (RTM) for reproducibility and low cost. This process is suitable for producing components of polymeric composites with relatively simple geometries, consistent thicknesses, high quality finish with no size limitations. The objective of this work was machined carbon steel to make a matched-die tooling for RTM and produce two composite plates of epoxy resin and carbon fiber fabric with and without induced discontinuities, which were compared towards their impregnation with ultrasound, their properties via tensile tests and thermal analysis. In ultrasonic inspection, it was found good impregnation of the preform of both composites. In the thermal analysis it was possible to check the degradation temperature of the composites, the glass transition temperature and it was found that the composites showed no effective cure cycles, but presented good performance in the tensile test when compared with aluminum alloy 7050 T7451 . The results showed that the injection strategy was appropriate since the laminate exhibited a good quality for the proposed application

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

Avaliação de sistemas de pultrudados com diferentes tipos de matrizes para aplicação em cabos condutores

In the last decades it has been observed a substantial developing of the electrical energy demand in the societies all over the World. In consequence the electrical energy distribution companies are increasing the quantity of electrical energy through the electrical energy conductor cables, which had grown the sag in the towers of energy transmission. Furthermore, the construction of more transmission towers brings a lot of troubles due environmental protection laws. In this way, looking forward to increase the quantity of electrical energy transmitted through electrical cables conductors, reduce the need of constructing new transmission towers and the sag in them, we suggest in this work the replace of the traditional core of the conductors cables commonly used, made of steel, by a core made by a composite material, which one is made by carbon fibers pultruded with polymeric resins as matrix. In a order to evaluate if the resins more commonly used in structural composites can be applied as matrix to make possible to use the composite material as a core, we made carbon fibers systems pultruded with epoxy, phenolic and polyester resins as matrix and a mechanic and physic-chemistry characterization was done on the systems by Tensile and Poisson tests, differential sprobe calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transformed infrared spectroscopy (FTIR), following their correspondents standards

Avaliação do efeito ambiental nas propriedades mecânicas e viscoelásticas de compósitos híbridos de titânio/fibra de carbono/resina epóxi

Hybrid composites combining metal plates and laminates with continuous fiber reinforced polymer, called fiber-metal (CHMF), have been particularly attractive for aerospace applications, due mainly to their high mechanical strength and stiffness associated with low density. These laminates (CHMF) consist of a sandwich structure consisting of layers of polymer composites and metal plates, stacked alternately. This setting allows you to combine the best mechanical performance of polymer composites reinforced with long fibers, to the high toughness of metals. Environmental effects should always be considered in the design of structural components, because these materials in applications are submitted to the effects of moisture in the atmosphere, the large cyclical variations of temperature around 82 ° C to -56 ° C, and high effort mechanical. The specimens of fibermetal composite were prepared at EMBRAER with titanium plates and laminates of carbon fiber/epoxy resin. This study aims to evaluate the effect of different environmental conditions (water immersion, hygrothermal chamber and thermal shock) of laminate hybrid titanium/carbon fiber/epoxy resin. The effects of conditioning were evaluated by interlaminar shear tests - ILSS, tensile, and vibration free

Influência do condicionamento ambiental sobre as propriedades viscoelásticas de compósitos aramida/epóxi

The increasing application of structural composites in the aerospace industry is mainly due to its low specific weight coupled with its excellent mechanical properties when in service. As a result of climatic variations that pass the aircraft is of paramount importance to study the influence of weathering on this type of material when subjected to such changes. The purpose of this work is to evaluate the mechanical behavior of specimens of kevlar fiber /epoxy matrix composites, by dynamic mechanical thermal analysis (DMA) and interlaminar shear strength tests (ILSS), after passing through three environmental conditioning: saline fog, hygrothermal and ultraviolet radiation. From the results, we concluded that the laminate was molded supplied homogeneously, not presenting problems such as porosity, delaminations or cracks inside. After a period of 625 hours of exposure to hygrothermal conditioning, we observed a 1,2% maximum of absorption of moisture. Samples subjected to the conditioning by UV irradiation (600 hours) and salt spray showed a reduction of about 24,30% and 32,30%, respectively, on the shear strength (ILSS). In DMA analysis is not observed significant changes on the glass transition temperature. However, when considering the storage modulus of the samples conditioned by UV radiation (1200 hours), salt spray and hygrothermal conditioning there is an increase of 5,34% , 7,19% and 5,57% respectively