José Manuel Rivas Mercury

Particleboard manufactured from Tauari (Couratari oblongifolia) wood waste using castor oil based polyurethane resin

Several wood species from the Amazon region are used in the manufacture of furniture, which leaves behind large amounts of waste (slabs, sawdust, sanding dust and bark), thus causing serious environmental impacts. An interesting alternative for the use of these wastes is the manufacture of particleboards. However, few studies have focused on the behavior of Amazonian tree species and the wastes resulting from production with this type of material. This paper discusses the potential use of Tauari (Couratari oblongifolia) wood waste as a raw material for the production of particleboards, using castor oil-based bi-component polyurethane adhesive. Experimental boards were prepared with dry wood particles and a castor-oil polyurethane adhesive content of 16%. The boards, whose nominal density was 1000 kg·m-3, were subjected to uniaxial compression (5 MPa) at 90, 110 and 130oC for ten minutes. The particleboards were characterized by performing the following tests: Apparent density (DAP), Moisture (M), Water Absorption (WA), Thickness Swelling (TS), Static bending strength: MOR (Modulus of rupture) and MOE (Modulus of elasticity), Perpendicular Tensile Strength (IB - internal bonding) and Screw Pullout (SP), according to the Brazilian NBR 14.810:2006 standard. The results indicate that, regardless of the processing temperature, the average density of Tauari particleboard is 930 to 941 kg·m-3, with higher IB and TS than those specified by the NBR 14810-2 and ANSI A208.1 standards, enabling this product to be classified as high-density particleboard suitable for industrial and commercial use.

Chemical and mineralogical characterization of portuguese ceramic tiles in the historic center of São Luís do Maranhão (Brazil): an approximation of the mineralogy and firing temperature of the raw materials

This work involved the first-ever characterization of antique Portuguese ceramic wall tiles in the Historic Center of Sao Luis do Maranhao, Brazil. The tiles were characterized by optical microscopy, X-ray diffraction (XRD) and chemical analysis to identify the possible raw materials used in the fabrication process, as well as the firing temperature of these materials. The results indicate that the microstructure of these materials consists of pores of varying sizes with calcite incrustations and quartz grain sizes smaller than 500 µm distributed in a pinkish yellow matrix, which were identified by XRD as calcite, gehlenite, wollastonite, quartz, and amorphous mineral phases. Based on this information, it can be inferred that the original raw materials probably consisted of a mixture of kaolinitic clays (Al2O3·2SiO2·2H2O) rich in calcium carbonates and quartz, or mixtures of kaolinitic clays, quartz and calcite, which did not reach the pre-firing temperature of 950oC.

Comportamento térmico e evolução das fases de óxidos de Mn com estrutura hollandita da região Amazônica

The tunnel-structure manganese oxide minerals, hollandite (Apui, Amazonas state, Brazil, area in prospection) and cryptomelane (Urucum, Mato do Sul Grosso state, Brazil) were isolated and characterized chemical, mineralogical, thermal and morphologically. The following techniques were employed: scanning electron microscopy-EDS, thermal analysis (DTA-TG), X-ray diffraction with continuous-heating. The empirical formula, were calculated on the basis 16 oxygen gave as (Ba 0.18 K 0.12 Ca 0.02 Pb 0.04 ) 0.76 (Mn 6.34 Al 0.61 Si 0.25 Fe 0.24 Ti 0.08 ) 7.54 O 16 0.4H 2 O for hollandite and (K 0.9 Na 0.04 Ca 0.03 Sr 0.04 ) 1.04 (Mn 7.38 Fe 0.28 Al 0.27 Si 0.08 ) 8 O 16 for cryptomelane. The SEM investigations allowed the differentiation of the morphologies for hollandite and cryptomelane. The minerals were thermally treated among 100-900 oC and X-ray diffraction patterns in situ were collected. The analysis of X-ray diffractions experiments showed that a hollandite-crytomelane mineral has a thermal stability up to 900 oC.

Caracterização química e mineralógica de birnessita natural da Mina do Azul (Província Mineral de Carajás, Brasil) e seu análogo sintético (K-OL-1) obtido pelo método sol-gel

O presente trabalho descreve um estudo comparativo das propriedades quimica e mineralogica de birnessita natural (BIR-AZ) proveniente da mina do Azul (Provincia Mineral de Carajas, Brasil) e seu analogo sintetico obtido pelo metodo sol-gel (K-OL-SG). As caracterizacoes foram realizadas por difracao de raios X, espectroscopia FT-Raman, analise termica (TG-DTA), microscopia eletronica de varredura e analise quimica. Os resultados confirmam a presenca das fases lamelares com sistema monoclinico, grupo espacial C2/m e com os seguintes parâmetros de cela unitaria: BIR-AZ, a = 5,148 A; b=2,843 A, c=7,175 A e β = 100,75o; K-OL-SG, a = 5,150 A; b = 2,846 A, c = 7,214 A e β = 101,29o. Birnessita possui estabilidade termica proxima a 600 oC, enquanto seu analogo sintetico acima de 900 oC. Bandas obtidas por espectroscopia Raman foram observadas a 635, 570 e 410 cm-1 e atribuidas as deformacoes Mn-O e K-O na estrutura lamelar. O estudo da morfologia dos produtos revela que birnessita se apresenta como folhas tabulares de 1 a 5 µm, enquanto que o composto sintetico possui morfologia em globulos (< 1 μm) dispostos aleatoriamente.

Ceramic raw materials from the State of Maranhão, Brazil. Part 1: chemical and mineralogical characterization and technological properties of clays from São Luis, Rosário, Pinheiro and Mirinzal

Nesse trabalho, foram caracterizadas algumas argilas coletadas nos municipios de Sao Luis, Rosario, Pinheiro e Mirinzal. A caracterizacao foi realizada atraves dos ensaios de difracao de raios X, massa especifica real, capacidade de troca de cations (CTC), area superficial, distribuicao granulometrica, analise quimica, analise termica (TG-DTA) e limites de Atterberg. Ensaios tecnologicos de retracao linear, antes e apos a queima, absorcao de agua e tensao de ruptura a flexao, em tres pontos, foram realizados em corpos de prova prensados uniaxialmente a 20 MPa e tratados termicamente em 850, 950, 1050, 1150 e 1250oC. Os resultados obtidos permitiram identificar duas argilas de queima branca, constituidas de quartzo, caolim, feldspato e anatasio, com excelentes propriedades para uso em cerâmica branca. As restantes sao queima vermelha e possuem composicao mineralogica de quartzo, caolim, feldspato, montmorilonita, hematita e goetita. Estas ultimas apresentaram valores moderados de plasticidade e sao adequadas para aplicacoes em cerâmica vermelha.