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Matsui M.,Federal University of Parana | Munaro M.,Institute Tecnologia Para O Desenvolvimento LACTEC | Akcelrud L.C.,Federal University of Parana
Journal of Polymer Research | Year: 2011

Aiming to combine the bioproperties of chitin with the mechanical characteristics of polyurethane these two polymers were interconnected through a tridimensional network. The networks were formed from the addition reaction of the terminal isocyanate groups of a urethane prepolymer and the acetamide and hydroxyl groups of chitin. The crosslinking density was set from the ratio between the reacting groups, since the polyurethane length was kept constant (M w∈=∈66 kD, M n∈=∈48 kD). The biodegradability of polyurethane was afforded by the polycaprolactone segment of this component. The physical properties of the networks were analyzed in correlation with the composition, and compared with previous results obtained from blends with the same composition. [Figure not available: see fulltext.] © 2011 Springer Science+Business Media B.V. Source

Ferreira R.A.,Sao Paulo State University | Ferreira R.A.,CNRS Chemistry Institute of Rennes | Dos Santos M.E.,Sao Paulo State University | Dos Santos M.E.,CNRS Chemistry Institute of Rennes | And 4 more authors.
Ceramics International | Year: 2014

Polycrystalline oxide materials with nominal compositions BiMn 2O5 and Bi0.9Eu0.1Mn 2O5 were obtained by urea combustion. Crystallographic studies using X-ray diffraction and Rietveld Refinement techniques showed the formation of single-phase samples for both compositions, crystallizing in a mullite-type orthorhombic perovskite structure, space group Pbam (Z=4). Replacement of Bi+3 by Eu+3 promoted a slight distortion and a unit cell contraction due to a decrease of the c-parameter for Bi 0.9Eu0.1Mn2O5. The SEM/EDX techniques confirmed the formation of single-phase materials with excellent mapping distribution. Magnetic measurements showed different behaviors: BiMn2O5 is an antiferromagnet (AFM) with a Néel temperature (TN) of 41 K and a Curie-Weiss temperature ΘCW of -277 K, while Bi0.9Eu0.1Mn 2O5 displayed a ferrimagnetic behavior with a T C of 44 K and ΘCW of -270 K. The role of Eu +3 and the mechanisms responsible for the magnetic transition are discussed on the basis of chemical bonds and exchange interactions. © 2014 Elsevier Ltd and Techna Group S.r.l. Source

Matsui M.,Federal University of Parana | Munaro M.,Institute Tecnologia Para O Desenvolvimento LACTEC | Akcelrud L.,Federal University of Parana
Polymer International | Year: 2010

Chitin is an abundant natural polymer having important properties such as biocompatibility and biodegradability combined with healing capability. Its use in biomedical applications has been hindered by its poor processing properties such as low solubility and stiffness in the solid state. In an attempt to obtain flexible and more processable chitin-based materials, we prepared blends of the polymer with a polyurethane containing a soft segment based on biodegradable polycaprolactone. A certain degree ofmiscibilitywas foundbetween chitin and the polyurethane, asdemonstrated by a shift in the glass transition of the polyurethane observed in dynamical mechanical analyses, with a simultaneous decrease in crystallinity of chitin observed in X-ray diffraction analyses. A phase inversion of the blends took place for a 50/50 (w/w) composition ratio as demonstrated from thermal, dynamic mechanical, tensile and X-ray diffraction measurements. Blends of chitin with the polycaprolactone-based polyurethane can be effectively used to produce tough materials useful in biomedical applications. The mechanical strength of the blends demonstrated that they are able to support tensions above those required for bone replacement, making them good candidates for that purpose. © 2010 Society of Chemical Industry. Source

Godoi W.C.,Institute Tecnologia Para O Desenvolvimento LACTEC | De Geus K.,Companhia Paranaense de Energia Copel | De Geus K.,Federal University of Parana | Swinka Filho V.,Institute Tecnologia Para O Desenvolvimento LACTEC
Insight: Non-Destructive Testing and Condition Monitoring | Year: 2010

In power distribution networks, polymer insulators commonly show flaws in their interior which cannot be perceived without the use of a non-destructive inspection mechanism. This work describes a methodology based on three-dimensional industrial computer tomography (CT) for the automatic detection of flaws in polymer insulators. CT slices were reconstructed using 180 digital radiographs (projections) acquired by a high-resolution system (pixel dimension of 50 ?m × 50 ?m). For the reconstruction of 3D CT, 50 ?m-wide bitmap slices were used. 3D segmentation and reconstruction is performed by the Marching Cubes algorithm implemented in the Visualization Toolkit (VTK) open-source library and in the Java programming language. The final step of the detection mechanism is performed by a neural network trained using nine features obtained from the reconstructed 3D objects. The estimated accuracy obtained by the proposed techniques is lower than that of the conventional technique. However, the available testing data are scarce and this makes it difficult to derive a definite conclusion on the correctness rate. The most important scientific contribution of this work resides in the fact that it is a promising work which may have great potential as far as automatic detection of flaws in polymer insulators based exclusively on the 3D domain is concerned, but this analysis must be addressed in future work. Source

Wolf L.D.,Federal University of Sao Carlos | Assumpcao M.H.M.T.,Federal University of ABC | Madi A.A.,Federal University of Sao Carlos | Bonifacio V.G.,Institute Tecnologia Para O Desenvolvimento LACTEC | Fatibello-Filho O.,Federal University of Sao Carlos
Ecletica Quimica | Year: 2011

In this article the construction of a simple calorimeter for the development of a protocol with which it is possible to determine the enthalpy of dissolution of salts is described. Thereunto, salts solutions such as sodium carbonate, sodium bicarbonate, copper sulfate and sodium chloride besides one thermometer and one expanded-polystyrene (Styrofoam) container were used. The experiment allows to assimilate Thermochemistry concepts and can be applied to any high school, since it uses materials easily obtainable at low cost. Source

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