Papers by Author: Antônio Hortêncio Munhoz Jr.

Abstract: The properties of composites based on thermosetting polyester and barite for use in the radiological protection area have been investigated with the objective to study the effect of different variables in the attainment of composites. To verify the efficiency of the composites produced in relation to radiological protection, lead was adopted as reference. A factorial experimental design was carried out and the studied variables were: type of polyester resin (orthophthalic or isophthalic), coupling agent (titanate or organosilane) and the ratio of resin to accelerator, catalyst and barite. The variables analyzed were: efficiency for barring the X-radiation, apparent density and mechanical properties. The effect, obtained from the experimental design, due to ratio of resin to barite in the apparent density was 0.036. The average apparent density of the samples produced with barite/resin value equal 2.0 (weight ratio) was 2.16g/cm3, while the average density of the samples produced with the weight ratio of barite/resin equal 3.0 was 2.2g/cm3. It was observed same trend for the density to mechanical properties. It was observed that the samples attenuated X-ray radiation adequately up to 116 kV.

Abstract: A pseudoboehmite was obtained by sol-gel synthesis using aluminum nitrate as precursor. It was used a 2n full factorial design for studying the effect of the temperature of synthesis, the concentration of ammonium hydroxide, and the radiation dose in the product of sol-gel synthesis. The product of the synthesis was analyzed by scanning electron microscopy, x-ray diffraction of the product (after firing the pseudoboehmite at different temperatures), and it was also analyzed the temperature of endothermic and exothermic transformations using the thermo gravimetric analysis (TG) and differential scanning calorimetry (DSC). The X-ray diffraction data show that α-alumina was obtained at 1100o C.