L. C. Machado

Polymethyl methacrylate (PMMA) recycling for the production of optical fiber sensor systems

This paper proposes the recycling of poly (methyl methacrylate) plates, formerly used in LCD monitors to produce polymer optical fibers without cladding for sensor systems and a discussion about the fabrication process of the fiber cladding is briefly presented. After disassembling LCD monitors the acrylic plate is cleaned and submitted to an extrusion process. Extrusion temperatures of 220°C, 230°C and 240°C were applied, and the produced polymer fibers were characterized by infrared and visible spectrometry, as well as evaluated for thermal analysis through differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Furthermore, a refractive index sensor was developed with the recycled fibers. Results show that the recycled fiber refractive index sensor is linear (R2 = 0.99) and presents a sensitivity of more than 4 times higher when compared to a sensor using a commercial POF.

Influence of ethyl alcohol in the preparation, morphology and properties of compound DAS–Eu3+ and its thermal degradation products

In this study, two compounds presenting characteristics different from each other were produced from there action between hydrated Eu3+ sulfate and Ba2+ diphenylamine-4-sulfonate using, respectively, aqueous solution for producing the Eu(C12H10NSO3)3·7H2O (A) compound and water/ethyl alcohol (7:1) solution for the Eu(C12H10NSO3)3·5H2O (B) production. The presence of alcohol molecules in the solution will interfere in the structural arrangement of anionic surfactant DAS− (diphenylamine-4-sulfonate) around the metal ions Eu3+ allowing differentiation in the stoichiometric formulas, morphology, and thermal properties of these compounds and their derivatives. Thus, when treating both compounds under oxidizing atmosphere, we found different temperatures of the water loss and conversion of the intermediate pair oxydisulfate [Eu2O(SO4)2]/dioxysulfate [(Eu2O2SO4)]. However, the effect of water/surfactant/alcohol interactions in the metal ion structural arrangement becomes still more evident under reducing atmosphere. After this thermal treatment, significant changes were observed in the morphological characteristics and physical properties of the (Eu2O2S oxysulfide) in compound B with respect to compound A.

Reaction products between sodium diphenyl -amine-4-sulfonate and hydrated LaCl3

This paper presents the reactions of synthesis between the ligand sodium diphenylamine-4-sulfonate and the lanthanum(III) chloride hydrated. The compounds (LaCl3)2·(C12H10NSO3Na)3·2(CH3CH2OH) (A) and (LaCl3)·(C12H10NSO3Na)·(CH3CH2OH)·12H2O (B) were obtained using the solvents ethanol and methanol (synthesis A) and ethanol and water (synthesis B). The produced compounds and the ligand were characterized by thermogravimetric and differential thermogravimetric analysis, IR spectroscopy and elemental analysis of sodium, carbon, hydrogen, nitrogen, sulfur, chlorine and lanthanum, whereas the residues from thermal decomposition were investigated by X-ray diffractometry.

Preparation and Mössbauer study of iron-mercury halide complexes containing isocyanide and carbonyl ligands

SummaryComplexes [Fe(t-BuNC)n(CO)5-n](n = 1 or 2) react with equimolar amounts of mercury(II) halides in acetone to form neutral iron-mercury adducts [Fe(t-BuNC) (CO)4−(HgX2)] and [Fe(t-BuNC)2(CO)3(HgX2)] (X = Cl or I), while [Fe(t-BuNC)5] reacts with solid mercury halides in petroleum ether to give the salts [Fe(t-BuNC)5(HgX)]-HgX3 (X = Br or I). Product assessment was based upon analytical and spectroscopic data, the Mössbauer effect and on molar conductivity studies.

Preparation and Mössbauer studies of iron-mercury mixed isocyanide-carbonyl complexes

The reactions of [Fe(t-BuNC)3(CO)2] with HgX2 (X= Cl, Br or I) give two different types of iron-mercury halide complex, depending on the molar ratio of reactants used. An equimolar ratio of the reactants produces the neutral adducts [Fe(t- BuNC)3(CO)2(HgX2)],whereas two equivalents of HgX2 generate the electrolytes [Fe(t- BuNC)3(CO)2(HgX)]HgX3. The Mössbauer, i.r. data, and conductivity measurements of these complexes are presented and discussed in terms of their chemical structures and bonding.

Development and test of a small resistive fault current limiting device based on Hg, Re-1223 and Sm-123 ceramics

Several reports describing Superconducting Fault Current Limiter (SFCL) containing members of the bismuth or yttrium ceramics were already described. However, none of these included the mercury and samarium cuprates. Consequently, we have conducted a study of a resistive-type superconductor fault current limiter based on Hg0.82Re0.18Ba2Ca2Cu3O8+d samples and SmBa2Cu3O7-d ceramics. All polycrystalline samples were prepared by solid-state reaction method using commercial oxide and carbonate powders. The superconducting ceramic with 2.4 × 2.6 × 6.0 mm3 dimensions was set up such that the electrical current flew through the area of 2.6 × 6.0 mm2. All measurements were done at 77K and without applied magnetic field (Happ = 0). In the case mercury sample, the fault current of 16.1 Apeak was reduced to 8.1 Apeak by the superconducting element and sustained for 100 ms. The prospective/limited of current ratio observed in this experiment was ~ 2.0, as considered a 2.4 mm pellet thickness. When the test was realized with the samarium sample, the prospective/limited current ratio observed was approximately 1.2, for same ceramic thickness. The tests confirmed the capability of the resistive type SFCL to limit the fault current. These results open the possibility of future investigations into SFCL devices based on those superconducting ceramics in low power electronics and electrical motor.

Estrutura e propriedades da difenil-4-amina sulfonato de sódio: um dopante de filmes condutores

This work contains the theoretical simulation of the conformation of diphenyl-4-amine sodium sulphonate (DASNa) and correlates its geometry with conductivity, showing that the conductivity increases as the molecule becomes more planar. The solvent effect was also evaluated, using water and dimethylsulfoxide. Some properties, such as bond distance, vibration al frequency and effective charge were calculated. The utilization of diphenyl-4-amine sodium sulphonate (DASNa) as dopant of aniline was investigated in view of the HOMO-LUMO energy gap.