Abstract Aiming to overcome poly(lactic acid) (PLA) limitations regarding flammability and high costs, a highly refractory clay (RC) was employed to produce PLA/RC composites. The composites with clay contents of 0, 2.5, 10 and 15 wt% were produced by extrusion, conformed by injection molding, and characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mechanical analysis, scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), statistical analysis of variance (ANOVA) and flammability tests. The overall thermal stability of the materials was not affected by the incorporation of clay to the polymer matrix; improvements around 25% for Young’s modulus and slight increase in flexural and impact strength, when compared to neat PLA, were obtained; ANOVA showed the possibility of incorporating higher loads of clay, 10-15 wt%, in order to make the final material more cost effective. PLA/RC composites demonstrated self-extinguish behavior for the flame even at a lower clay content.

ABSTRACT The present work aimed to characterize the firing behavior of glazes formulated using samples of rocks from the region of Poços de Caldas as a substitute for feldspar. Four formulations were performed, using samples before and after a magnetic separation process. The raw materials were analyzed for their chemical-mineralogical characteristics and the formulations were characterized using Binil Surface Application and fusibility button test, in colorimetric and brightness analyzes. The formulations were also characterized for their coloration compared to the standard glaze, holding nepheline. It was verified that the potassium rock sample presented dark colors (post-magnetic separation), making it impossible to use. The foyaite samples showed promising results, before and after the magnetic separation. According to the results of the colorimetric analysis as the fusibility tests were performed, the non-magnetic samples were clearer due to a comparison of the standard sample of nepheline in both fluorescent light and sunlight, indicating that these samples have potential for use in the formulation of glazes and are interesting alternatives to nepheline and feldspars.

RESUMO Na fabricação do concreto, cimento (o Portland é o mais usado), água e agregados (classificados em finos e grossos), são usados. Com a utilização de inúmeras matérias-primas, a geração de resíduos é inevitável, seja na construção civil ou em outros setores, como as indústrias produtoras de materiais cerâmicos. Entre os tipos de resíduos destas indústrias, pode ser mencionado o scrap cerâmico (proveniente da indústria de louças sanitárias). Sendo assim, o objetivo deste trabalho foi estudar a adição de scrap cerâmicso como agregado graúdo em diferentes proporções na formulação de concretos. Para isso, foram selecionados resíduos de uma indústria do sul de Minas Gerais, e foram preparados corpos de prova para determinação das propriedades do concreto fresco (slump teste, segregação e porosidade) e endurecido (resistência à compressão) das diferentes formulações do concreto. Foram confeccionadas 5 diferentes formulações, uma de referência (CR) e quatro com resíduo cerâmico como substituinte do agregado graúdo nas proporções de 25% (CSC-I), 50% (CSC-II), 75% (CSC-III) and 100% (CSC -IV). Em relação aos concretos frescos, duas formulações não apresentaram segregação (CSC-III and CSC-IV) e duas um pequeno escorrimento de água (CSC-I and CSC-II ), entretanto, em comprometer a trabalhabilidade do concreto. Em relação às resistência à compressão, os valores médios apresentados foram satisfatórios, incluindo a formulação com 100% de scrap cerâmico (fc = 47.78 MPa). Outro importante aspecto observado nos modos de ruptura dos corpos de prova foi a pequena adesão entre o resíduo de louça sanitária e a argamassa devido à camada de esmalte no contorno do resíduo. Em relação à porosidade das formulações, aquelas com 25, 75 e 100% de resíduo apresentaram valores mais baixos em relação ao concreto de referência.

ABSTRACT In concrete manufacture, cement (Portland type is the most used), water and aggregates (classified into coarse and fine) are used. With the use of several raw materials the generation of waste is inevitable, both in construction and in other sectors, such as the industries producing ceramic materials. Among the types of waste from such industries, can be mentioned the ceramic scrap (from the sanitary ware industry). According to the above, the aim of this research was to study the addition of ceramic scrap as a coarse aggregate in different proportions in the concrete formulation. In order to do this, was select wastes from an industry in the south of Minas Gerais (Brazil), and prepare specimens to determine the fresh (slump test, adhesiveness and porosity) and hardened (compression strength) of concrete. Were fabricated five concrete formulations, one reference (RC) and four with ceramic scrap substituted for coarse aggregate in the proportions of 25% (CSC-I), 50% (CSC-II), 75% (CSC-III) and 100% (CSC -IV). Fresh concretes, two formulations did not show adhesiveness (CSC-III and CSC-IV) and two a small water runoff (CSC-I and CSC-II), however, without compromising the concrete’s workability. Regarding the compression strength, the average values presented were very good, including the formulation with 100% ceramic scrap (fc = 47.78 MPa). Another important aspect observed in the rupture modes was the small adhesion between the ceramic scrap and the mortar due to the glazing in the contour of the waste. As for the porosity of the concretes, those with 25%, 75% and 100% of ceramic scrap in their composition presented lower values than the reference concrete.

The thermal treatments employed in alloys are essential to obtaining desired microstructures and corrosion resistance properties. In this paper the low carbon martensitic steel 13Cr4Ni0.2C with different tempering temperatures was studied using potentiodynamic polarization technique in synthetic marine environment, in order to evaluate the effect of the tempering temperature on the steel corrosion resistance in an environment that simulates the conditions of use in oil and gas production. Microscopy results showed differences in the microstructure of tempered steel at low (620°C) and high (770°C) temperatures, indicating the appearance and extending of martensite laths with increasing temperature. Polarization tests showed that tempering temperature located between 620°C and 710°C indicated passive film formation and tempering temperatures of around 620 °C showed better resistance values to pitting corrosion.

This paper describes the development of TiO2 and ZnO particles by a chemical route, using two different wet synthesis methods: polymeric precursor (PP) and sol-gel (SG). This study aimed to shed a light on how the synthesis method affects the photocatalytic activity of these oxides. Rhodamine B (RhB) degradation was used as a probe reaction to test the as-synthesized TiO2 and ZnO photoactivity. It was observed that surface availability, which is related to the presence of synthesis residue, is the key parameter to determine photoactivity. ZnO PP and ZnO SG presented degradation of 88% to RhB. Both samples presented synthesis residue on the surface. On the other hand, TiO2 PP presented a better performance than TiO2 SG, once 90% of RhB was degraded, while TiO2 SG degraded 80% of the dye. In this case, TiO2 PP was free of synthesis residue on the surface, while TiO2 SG presented residues.

Introduction: Bone diseases, aging and traumas can cause bone loss and lead to bone defects. Treatment of bone defects is challenging, requiring chirurgical procedures. Bone grafts are widely used for bone replacement, but they are limited and expensive. Due to bone graft limitations, natural, semi-synthetic, synthetic and composite materials have been studied as potential bone-graft substitutes. Desirable characteristics of bone-graft substitutes are high osteoinductive and angiogenic potentials, biological safety, biodegradability, bone-like mechanical properties, and reasonable cost. Herein, we prepared and characterized potential bone-graft substitutes composed of calcium phosphate (CP) - a component of natural bone, and chitosan (CS) - a biocompatible biopolymer. Methods CP-CS composites were synthetized, molded, dried and characterized. The effect of drying temperatures (38 and 60 °C) on the morphology, porosity and chemical composition of the composites was evaluated. As well, the effects of drying temperature and period of drying (3, 24, 48 and 72 hours) on the mechanical properties - compressive strength, modulus of elasticity and relative deformation-of the demolded samples were investigated. Results Scanning electron microscopy and gas adsorption-desorption analyses of the CS-CP composites showed interconnected pores, indicating that the drying temperature played an important role on pores size and distribution. In addition, drying temperature have altered the color (brownish at 60 °C due to Maillard reaction) and the chemical composition of the samples, confirmed by FTIR. Conclusion Particularly, prolonged period of drying have improved mechanical properties of the CS-CP composites dried at 38 °C, which can be designed according to the mechanical needs of the replaceable bone.