ABSTRACT In this work, magnesium oxide nanoparticles were synthesized by the sol-gel route and their ecotoxicity was tested in worms of the Eisenia andrei species. Magnesium oxide nanoparticles were characterized by XRD, surface area via BET, TEM and SEM-FEG/EDS. The lethality test with Eisenia andrei earthworm species followed the recommendations of ISO 11268-1 (ISO, 2012) in a completely randomized design with six replicates for each concentration tested (1.06, 2.12, 4.24, 8.48 and 16.96 μg of NPs-MgO/kg of soil), plus the control. The concentrations were mixed to the tropical natural soils, Entisol Typic Quartzipsamments and Oxisol, with no agricultural use history. The morphological and structural analyses of the nanoparticles indicated the formation of magnesium oxide with cubic structure, constituting agglomerates of nanostructures of the order of 20 to 50 nm. The results of toxicity were submitted to analysis of variance (ANOVA One-way), followed by the Dunnett test (p <0.05). Based on standardized toxicological tests it was found that NPs-MgO, at the concentrations tested, did not affect the survival of Eisenia andrei species in the natural soils studied.

Abstract In order to minimize environmental impact zeolite A was synthesized using waste from the paper industry. This waste is composed of cellulose, kaolin and calcium carbonate. Waste purification was carried through thermal and chemical treatment, which consisted of initial calcination, acid washing with HCl, then calcination of the solid fraction to obtain metakaolin and evaporation of the liquid fraction to obtain CaCl2. Zeolite 4A was produced by static autoclaving under hydrothermal synthesis at different temperatures, crystallization times and NaOH concentrations. As a source of aluminum and silicon metakaolin was used. The synthesis of zeolite 5A was performed by ion exchange with CaCl2. After that, the waste paper (in natura and HCl treatment) and the zeolites 4A and 5A were characterized by XDR, SEM, FTIR, AAS and thermal analysis. The temperature is a key factor in zeolite synthesis at lower concentrations allowing one to obtain zeolite 5A by ion exchange with zeolite 4A.

ABSTRACT This work describes the second of a series of studies of the effects of injection molding conditions on the mechanical and thermal properties of Polyamide 6/Glass Fiber/Montmorillonite (PA6/GF/MMT) composites and was motivated by the lack of information about how the processing variables influence on the properties of three-phase composites containing fiber glass. By this time, the effects of the injection molding temperature associated with the fiber glass percentage on the mechanical and thermal properties of the composite are investigated. Some samples were processed, following a statistical experimental factorial planning, varying the mold temperature and the fiber glass percentage and maintaining 5 wt % of the MMT. The samples were submitted to tensile and flexural tests, XRD, SEM and DSC. The studies showed that an increase in the mold temperature and the fiber percentage improves the maximum tensile and flexural stresses. The increased mold temperature slows the cooling rate, which, over time, decreases the degree of crystallinity. However, there is an increase in the intercalation of the polymeric chains and the nanoclay lamellae, and the structure forms with fewer defects.

The U-Mo alloys are investigated with the goal to become nuclear material to fabricate high-density fuel elements for high performance research reactors. The enrichment level (20% 235U) suggests that the U-Mo alloys should be between 6 to 10 wt. (%), which can reach up to 9 gU.cm-3 in fuel density. Nevertheless, the U-Mo alloys are very reactive with Al. Interdiffusion reaction products are formed since nuclear fission promotes chemical interaction layer during operation, leading to potential structural failure. Present studies were made with treated hot rolled diffusion couples of U-10Mo inserted in Al (AA1050). The U-10Mo/AA1050 pairs were treated in two temperatures (150 ºC and 550 ºC) with three soaking times (5, 40 and 80 hours). From microstructure analyses, rapid diffusion of Al happened inside U-10Mo in the first heating at 540 ºC during 15 minutes, reaching 8 at% Al in a range of 170 μm towards U-10Mo. Longer time at 550 ºC treatment maintain this level of Al-content up to 1000 μm inside U-10Mo. In this study, the results suggested the formation of a barrier made by residual elements, which promoted little interdiffusion phenomena between U-10Mo and alloy AA1050. Silicon co-diffusion with Al, along the interdiffusion line, is thought to be an important indication for this interdiffusion blockage.

This work evaluates the effect of ZnCl2 and Zn(NO3)2.6H2O as precursors in the synthesis of ZnO nanocrystals. The materials were obtained at 90 ºC by a simple solochemical route. The resulting samples were characterized regarding phase composition, particle size and morphology, by means of XRD and TEM. The analysis have provided evidences that the material obtained applying Zn(NO3)2.6H2O as precursor has hexagonal crystalline structure, typical of the ZnO, and dimensions in the nanoscale. However, applying ZnCl2 as precursor results in a mixture of ZnO and Zn5(OH)8Cl2.H2O phases. For both precursors, the predominant morphology of the obtained ZnO nanocrystals was the rod-like structure.

Bottom ash has been used as raw material to glass and glass ceramic production because it is a source of SiO2 and Al2O3. However, the high concentration of iron (about 10% wt.) difficulty the control of the nucleation and the crystallization processes. The iron content was reduced by magnetic process, where the magnetite phase was mainly removed. In order to compare glass ceramics obtained from original and low iron bottom ashes, microstructural and dilatometric characterizations were performed.