Materials Science Forum Vols. 775-776

Abstract: The present study reports the results obtained from Sewage Sludge SS for the obtainment of bio-oil through the pyrolysis process. The research aimed to evaluate the thermal and kinetic behavior of the bio-solid. In this work studies were made on physicochemical, elemental analysis (CHNO). Thermogravimetry (TG) with heating rate of 10o C min^-1 over two atmospheres (synthetic air and N₂), Thermodynamics (ΔH, ΔS e ΔG), kinetic and spectroscopic. The thermalgravimetric study stated a thermal stability at 30°C. The kinetic calculations were made aiming to observe parameters such as: Activation energy (Ae), frequency factor (s^-1), standard deviation (sd) and linear coefficient (r), which were calculated by Thermogravimetry by the methods of Coats-Redfern (CR); Madhusudanan (MD); Van Krevelen (VK); Horowitz-Metzger (HM). In the spectrometry in the infrared (IR) region it was observed bands referring to the presence of water, organic material and silicon oxides in the SS samples analyzed.

Abstract: Polymeric membranes are attracting attention of researchers and industries due to their lower costs. However, they also have lower mechanical resistance and chemical solvents, when compared with other materials. An improvement of polymer properties can be obtained by adding an inorganic nanoload in the structure. This study produced polyamide 6 / bentonite clay nanocomposites with a nominal content of 3%, and this was used in the processed form and in the organically modified form by cation exchange. The nanocomposites were produced by melt intercalation, and then, the membranes were obtained by the technique of immersion-precipitation. Bentonite, organophilic clay, the material processed in the extruder and the membranes were submitted to the x-ray diffraction (XRD) and infrared spectroscopy (ATR-FTIR). By both techniques, it was possible to prove the organic modification of clay and the change in the crystallinity of the nanocomposites and of the membranes.

Abstract: Polymer blend is the name for the physical mixture of two or more polymers and/or copolymers, and this allows the obtention of new materials with superior properties to those of the pure components. The blends have been used in obtaining membranes in order to improve the barrier properties so that it can separate two phases totally or partially, restricting the transport of one or more chemical species. In this work, polymer membranes were obtained from blends of PA6/PPgAA and PA6/PP/PPgAA by phase inversion method and were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was observed through the diffractograms that there were no significant variations in the characteristic peaks of PA6, and through SEM, it was observed the formation of microporous asymmetric membranes, where they showed a surface with higher porosity to the binary and ternary blends and presented smallest pore diameter for binary blends.

Abstract: In this study bionanocomposites were prepared from biodegradable polymer matrices such as poly (lactic acid) (PLA) and PBAT/PLA blend commercially known as Ecovio^®, with abundant smectite clays in Paraíba and modified (OMMT) with Praepagen quaternary ammonium salt. Systems with PLA and with the blends of PBAT/PLA were prepared with addition of bentonite clay at a concentration of 3wt.%. in a twin screw corrotational extruder. The systems containing PLA/OMMT and blend of PBAT/PLA/OMMT were characterized by X-ray diffraction (XRD) and Heat Deflection Temperature (HDT). From the diffractograms of bionanocomposites PLA/OMMT and PBAT/PLA/ OMMT it was observed a probably microcomposite structure. It was also observed that the HDT of PBA/PLA/OMMT and the blend of PBAT/PLA bionanocomposites was lower in relation to pure PLA and its PLA/OMMT bionanocomposite.

Abstract: The environmental concern is creating pressure for the substitution of energy intensive synthetic materials for natural and sustainable ones. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as flexibility and toughness. So there is today a growing worldwide interest in the use of natural fibers. Buriti fiber extracted from the petiole of buriti palm tree (Mauritia flexuosa), presents some significant characteristic, but until now only few studies on buriti fiber were performed. This work aims to study the tensile strength of polyester composites reinforced with buriti fibers. This study was performed in relatively thinner fibers with diameters between 0.1 and 0.4 mm. Those fibers were incorporated into the polyester matrix with volume fraction from 0 to 30%. The fiber diameters were measured by a profile projector. After fracture the specimens were analyzed by scanning electron microscope (SEM). The results showed a sensible improvement in the mechanical properties. The SEM observation revealed the mechanism for this improvement.

Abstract: This research aims to synthesize ZrO₂ by combustion reaction in batches of 15 g of the product and to evaluate the calcination influence on the structural and morphological characteristic about synthesized sample. For the synthesis of ZrO₂, the stoichiometry of phase was established in accordance with the propellants and explosives chemical concept, whereas the stoichiometric coefficient φ =1. After the synthesis, the sample as synthesized was calcined at 600 and 700°C and subsequently characterized by XRD, SEM, textural analysis (BET) and FTIR. The results have shown to the sample as synthesized and then calcined at 600°C the majority phase formation of orthorhombic zirconia with monoclinic phase dashes. The temperature increase to 700°C, has been transformed a part of the orthorhombic ZrO₂ to a monoclinic phase, contributing to a surface area reduction of the samples, showing irregular agglomerates in morphology, with adsorption/desorption isotherms type IV and mesoporosity characteristic.

Abstract: The aim of this work is to evaluate different forms to minimize the scattered radiation contribution in digital radiographic images of offshore pipelines using MCNPX simulations. The influence of oil inside the pipe, seawater surrounded the pipelines and external coating in the scattering component of the radiation beam will be analyzed. The use of backscattering shielding and lead screen will be discussed.

Abstract: The Alto Paranaiba and Triângulo Mineiro mesoregion in the state of Minas Gerais and the State of São Paulo have a number of industries with eucalyptus chip fired boilers that produce great amounts of ash. Since thermoelectric ashes generally have good pozzolanic activity, this paper studied the mechanical behavior of cementitious composites made with raw eucalyptus chip ash as a partial replacement for Portland cement and processed under two different conditions. The mechanical behavior of the composites was measured from tests on specimens for their compressive strength, tensile strength to diametral stress and to bending. Results show ashes could be used as mineral additives.

Abstract: Geopolymers, also known as inorganic polymers, are aluminosilicates with cementing characteristics that have great application potential. They are produced by the alkaline activation of aluminosilicates precursors such as industrial wastes, calcined clays, natural minerals, among others and have their properties intimately associated to characteristics of the precursor materials and curing conditions. In this sense, this study aims to evaluate the mechanical behavior of geopolymers obtained from metakaolin according to the curing temperature. The geopolymerization was reached by the mixture of metakaolin with NaOH and the curing of the specimens was held at room temperature, 60°C and 100^°C. The specimens were characterized by X-ray diffraction, mercury intrusion porosimetry, and SEM. The mechanical strength was determined by flexural test. The results show that the process of geopolymerization suffers a direct influence of the curing temperature used.

Abstract: The incorporation of biodiesel in the worldwide energetic matrix has an increasing tendency to use in the world. However, there are many technological challenges to consolidate this biofuel as an alternative to fossil fuels. The evaluation of the materials compatibilities used in the automotive industry and biodiesel production chain has been configured as an important area of research in finding appropriate materials that comes into contact with diesel biodiesel/blends. The present work aims to evaluate the physical properties for elastomeric composites prepared with polymeric matrix of ethylene propylene diene monomer (EPDM), acrylonitrile-butadiene rubber (NBR), natural rubber (NR) and styrene-butadiene rubber (SBR). The composites were prepared under controlled conditions of mixing and vulcanization. The elastomeric composites were aged in a blend containing 95 vol% of diesel and 5 vol% of biodiesel (B5 blend). The static total immersion tests were carried out at controlled temperature (50°C) for 7, 14, 21 and 28 days, substituting the B5 blend every 7 days. The results showed that the properties of NBR are less affected than other elastomers. It showed better mechanical performance and less influence on the glass transition temperature, indicating less degradation of this rubber in contact with B5 blend used in immersion tests.