RESUMO

Natural fiber composites have been extensively studied for structural applications, with recent exploration into their potential for various uses. This study investigates the impact of chemical treatments on the properties of Brazilian jute woven fabric/polyester resin composites. Sodium hydroxide, hydrogen peroxide, and peracetic acid were utilized to treat the jute fabrics, followed by resin transfer molding (RTM) to form the composites. Evaluation included water absorption, flexural strength, tensile strength, and short-beam strength. The alkaline treatment induced changes in the chemical composition of the fibers' surface. Chemical treatments resulted in increased flexural and short-beam strength of the composites, with no significant alterations in tensile properties. The hydrogen peroxide treatment exhibited lower water absorption, suggesting its potential as a viable option for enhancing the performance of these composites.

RESUMO

Composites based on virgin and recycled polypropylene (PP and rPP) reinforced with 15 wt% sisal fibers, with and without alkali treatment, were prepared by compression molding in a mat composed of a three-layer sandwich structure. The sisal was characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The composites were characterized according to physical and mechanical properties. Additionally, a factorial experimental design was used to statistically evaluate the mechanical properties of the composite. The FTIR and XRD indicated the partial removal of amorphous materials from the surface of the sisal after alkali treatment. The composites' density results varied from 0.892 to 0.927 g·cm-3, which was in the desirable range for producing lightweight automotive components. A slight decrease in the hardness of the pure rPP and rPP composites in relation to the PP was observed. The water absorption was higher in rPP composites, regardless of the chemical treatment. Moreover, the impact resistance of PP and its composites was higher than the values for rPP. Statistical analysis showed that the alkali treatment was a significant factor for the hardness of the rPP and PP composites, and that the addition of the sisal layer was relevant to improve the impact resistance of the composites.

RESUMO

This study compares the structural and morphological changes in Guadua angustifolia Kunth (GAK) fiber prepared in three different ways (chips, barkless and crushed) when non-conventional alkaline treatment is applied. Moreover, it shows the improvement of mechanical properties of cement composites reinforced with these treated fibers. The three different preparations of Guadua were treated with a saturated solution of calcium hydroxide (5%) at 125 °C and 1.25 kPa for 3 h to remove non-cellulosic compounds. Then, their chemical, morphological, and structural properties were examined. The fibers exhibiting the higher delignification rate were selected to prepare cement composite boards, whose mechanical properties were successively compared with those of composites reinforced with untreated G. angustifolia fibers. The water/cement ratios of the cement mixed with the Ca(OH)2-treated and the untreated fibers were, respectively, around 0.3 and 0.25. The flexural strength and toughness of the two composites were evaluated after 7, 28, and 90 days of curing. The calcium hydroxide treatment showed higher efficiency in removing non-cellulosic materials when performed on crushed bamboo; moreover, the mechanical properties of the composites reinforced with the treated fibers were higher than those mixed with the untreated ones. After 90 days of curing, the flexural strength increased by around 40% and the toughness became three times higher (p < 0.05). The mechanical improvement by the Ca(OH)2 treatment of G. angustifolia fibers demonstrates its potential for the fabrication of cement composites.

RESUMO

The objective was to evaluate the chemical composition and in vitro digestibility of sugarcane hydrolysed with increasing doses of calcium oxide and varying air exposure times. A completely randomised, split plot design was used; the doses were allocated to the plots, and the air exposure times were allocated to the subplots, with four repetitions. The data underwent analysis of variance and were laid out according to the effect of the treatment on the components of polynomial regressions, and evaluated at the 5% probability. The increase in the dosage negatively affected the quantities of neutral-detergent fibre (NDF), acid-detergent fibre (ADF), lignin (LIG), total carbohydrates (TC), cellulose (CEL), crude protein (CP), and ether extract (EE); and positively affected the quantities of non-fibrous carbohydrates (NFC) and mineral matter (MM). The addition of calcium oxide improved the in vitro digestible dry matter (IVDMD) coefficients and was able to keep up to 72 hours. The in vitro digestibility of the neutral-detergent fibre (IVDNDF) and of the acid-detergent fibre (IVDADF) coefficients decreased when calcium oxide was added. Calcium oxide has the ability to hydrolyse the fibrous fraction and conserve chopped sugarcane. Doses of 0.5 and 1.0% lime exhibited similar results to those achieved at higher doses; therefore, higher doses are not required in the hydrolyses of sugar...(AU)

Objetivou-se avaliar a composição bromatológica e a digestibilidade in vitro da cana-de-açúcar hidrolisada com doses crescentes de óxido de cálcio e diferentes tempos de exposição ao ar. Utilizouse o delineamento inteiramente casualizado, em esquema de parcelas subdivididas, sendo as doses alocadas nas parcelas e os tempos de exposição ao ar nas subparcelas, com quatro repetições. Os dados foram submetidos à análise de variância e desdobrados quanto ao efeito de tratamento nos componentes de regressões polinomiais, e avaliados a 5% de probabilidade. A elevação das doses influenciou negativamente os teores de FDN, FDA, LIG, CT, CEL, PB e EE, e positivamente nos teores de CNF e MM. A utilização do aditivo melhorou os coeficientes de DIVMS e foi capaz de manter até 72 horas. Houve decréscimo nos coeficientes de DIVFDN e DIVFDA com a adição de óxido de cálcio. O óxido de cálcio tem capacidade de hidrolisar a fração fibrosa como também conservar a cana-de-açúcar já picada. As doses 0,5 e 1,0% de cal, apresentaram resultados semelhantes às doses superiores, não havendo necessidade de utilização de doses mais elevadas na hidrolise da cana-de-açúcar. Com o decorrer do tempo ocorre deterioração da cana-de-açúcar, porém esta é menor quando tratada com óxido de cálcio.(AU)

Assuntos

RESUMO

The objective was to evaluate the chemical composition and in vitro digestibility of sugarcane hydrolysed with increasing doses of calcium oxide and varying air exposure times. A completely randomised, split plot design was used; the doses were allocated to the plots, and the air exposure times were allocated to the subplots, with four repetitions. The data underwent analysis of variance and were laid out according to the effect of the treatment on the components of polynomial regressions, and evaluated at the 5% probability. The increase in the dosage negatively affected the quantities of neutral-detergent fibre (NDF), acid-detergent fibre (ADF), lignin (LIG), total carbohydrates (TC), cellulose (CEL), crude protein (CP), and ether extract (EE); and positively affected the quantities of non-fibrous carbohydrates (NFC) and mineral matter (MM). The addition of calcium oxide improved the in vitro digestible dry matter (IVDMD) coefficients and was able to keep up to 72 hours. The in vitro digestibility of the neutral-detergent fibre (IVDNDF) and of the acid-detergent fibre (IVDADF) coefficients decreased when calcium oxide was added. Calcium oxide has the ability to hydrolyse the fibrous fraction and conserve chopped sugarcane. Doses of 0.5 and 1.0% lime exhibited similar results to those achieved at higher doses; therefore, higher doses are not required in the hydrolyses of sugar...

Objetivou-se avaliar a composição bromatológica e a digestibilidade in vitro da cana-de-açúcar hidrolisada com doses crescentes de óxido de cálcio e diferentes tempos de exposição ao ar. Utilizouse o delineamento inteiramente casualizado, em esquema de parcelas subdivididas, sendo as doses alocadas nas parcelas e os tempos de exposição ao ar nas subparcelas, com quatro repetições. Os dados foram submetidos à análise de variância e desdobrados quanto ao efeito de tratamento nos componentes de regressões polinomiais, e avaliados a 5% de probabilidade. A elevação das doses influenciou negativamente os teores de FDN, FDA, LIG, CT, CEL, PB e EE, e positivamente nos teores de CNF e MM. A utilização do aditivo melhorou os coeficientes de DIVMS e foi capaz de manter até 72 horas. Houve decréscimo nos coeficientes de DIVFDN e DIVFDA com a adição de óxido de cálcio. O óxido de cálcio tem capacidade de hidrolisar a fração fibrosa como também conservar a cana-de-açúcar já picada. As doses 0,5 e 1,0% de cal, apresentaram resultados semelhantes às doses superiores, não havendo necessidade de utilização de doses mais elevadas na hidrolise da cana-de-açúcar. Com o decorrer do tempo ocorre deterioração da cana-de-açúcar, porém esta é menor quando tratada com óxido de cálcio.

Assuntos

RESUMO

In this study, in vitro cytocompatibility was investigated in the Ti-30Ta alloy after two kinds of surfaces treatments: alkaline and biomimetic treatment. Each condition was evaluated by scanning electron microscopy/energy-dispersive X-ray spectroscopy. Cellular adhesion, viability, protein expression, morphology, and differentiation were evaluated with Bone marrow stromal cells (MSCs) to investigate the short and long-term cellular response by fluorescence microscope imaging and colorimetric assays techniques. Two treatments exhibited similar results with respect to total protein content and enzyme activity as compared with alloy without treatment. However, it was observed improved of the biomineralization, bone matrix formation, enzyme activity, and MSCs functionality after biomimetic treatment. These results indicate that the biomimetic surface treatment has a high potential for enhanced osseointegration.

Assuntos

RESUMO

The aim of this study was to evaluate the mineral composition of in natura sugarcane hydrolyzed with increasing doses of quicklime and different periods of exposure to air. The levels of quicklime (CaO) used were 0.0 (control); 0.5; 1.0; 1.5 to 2.0% based on natural matter of cane and the time of exposure to air at 0; 24; 48; 72 and 96 hours. The mineral composition was assessed through the concentrations of calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg), zinc (Zn), copper (Cu), manganese (Mn), chromium (Cr), lead (Pb) and cadmium (Cd). We used a completely randomized design. Data were analyzed using analysis of variance with repeated measures for comparison of means by Tukey test at 5% probability was used.(AU)

Objetivou-se avaliar a composição mineral da cana-de-açúcar in natura hidrolisada com doses crescentes de cal virgem e diferentes tempos de exposição ao ar. As doses de cal virgem (CaO) utilizadas foram 0,0 (controle); 0,5; 1,0; 1,5 e 2,0% com base na matéria natural da cana e os tempos de exposição ao ar 0; 24; 48; 72 e 96 horas. A composição mineral foi avaliada através das concentrações cálcio (Ca), fósforo (P), potássio (K), magnésio (Mg); zinco (Zn), cobre (Cu), manganês (Mn), cromo (Cr), chumbo (Pb) e cádmio (Cd). Utilizou-se o delineamento inteiramente casualizado. Os dados foram analisados utilizando uma análise de variância com medidas repetidas, para a comparação das médias foi utilizado o teste de Tukey ao nível de 5% de probabilidade.(AU)

Assuntos

RESUMO

The aim of this study was to evaluate the mineral composition of in natura sugarcane hydrolyzed with increasing doses of quicklime and different periods of exposure to air. The levels of quicklime (CaO) used were 0.0 (control); 0.5; 1.0; 1.5 to 2.0% based on natural matter of cane and the time of exposure to air at 0; 24; 48; 72 and 96 hours. The mineral composition was assessed through the concentrations of calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg), zinc (Zn), copper (Cu), manganese (Mn), chromium (Cr), lead (Pb) and cadmium (Cd). We used a completely randomized design. Data were analyzed using analysis of variance with repeated measures for comparison of means by Tukey test at 5% probability was used.

Objetivou-se avaliar a composição mineral da cana-de-açúcar in natura hidrolisada com doses crescentes de cal virgem e diferentes tempos de exposição ao ar. As doses de cal virgem (CaO) utilizadas foram 0,0 (controle); 0,5; 1,0; 1,5 e 2,0% com base na matéria natural da cana e os tempos de exposição ao ar 0; 24; 48; 72 e 96 horas. A composição mineral foi avaliada através das concentrações cálcio (Ca), fósforo (P), potássio (K), magnésio (Mg); zinco (Zn), cobre (Cu), manganês (Mn), cromo (Cr), chumbo (Pb) e cádmio (Cd). Utilizou-se o delineamento inteiramente casualizado. Os dados foram analisados utilizando uma análise de variância com medidas repetidas, para a comparação das médias foi utilizado o teste de Tukey ao nível de 5% de probabilidade.

Assuntos

RESUMO

The aim of this study was to evaluate the mineral composition of "in natura" sugarcane hydrolyzed with increasing doses of quicklime and different periods of exposure to air. The levels of quicklime (CaO) used were 0.0 (control); 0.5; 1.0; 1.5 to 2.0% based on natural matter of cane and the time of exposure to air at 0; 24; 48; 72 and 96 hours. The mineral composition was assessed through the concentrations of calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg), zinc (Zn), copper (Cu), manganese (Mn), chromium (Cr), lead (Pb) and cadmium (Cd). We used a completely randomized design. Data were analyzed using analysis of variance with repeated measures for comparison of means by Tukey test at 5% probability was used. The Ca concentration changes (P 0,05) caused a modification of the Ca:P ratio in the hydrolyzed sugarcane that reached 36.46:1 at the highest dose of lime (2.0%). The levels of P, K, Mg, Zn and Cu decreased with increasing levels of quicklime (P 0,05). Regarding to the period of exposure to air, there was an increase in the concentration of K, Mg, and Mn (P 0,05). The treatment of sugarcane with microprocessed quicklime (CaO) increases the Ca content of the forage. Pb is present in the quicklime but in a concentration well below the toxic concentration for ruminants.

Objetivou-se avaliar a composição mineral da cana-de-açúcar in natura hidrolisada com doses crescentes de cal virgem e diferentes tempos de exposição ao ar. As doses de cal virgem (CaO) utilizadas foram 0,0 (controle); 0,5; 1,0; 1,5 e 2,0% com base na matéria natural da cana e os tempos de exposição ao ar 0; 24; 48; 72 e 96 horas. A composição mineral foi avaliada através das concentrações cálcio (Ca), fósforo (P), potássio (K), magnésio (Mg); zinco (Zn), cobre (Cu), manganês (Mn), cromo (Cr), chumbo (Pb) e cádmio (Cd). Utilizou-se o delineamento inteiramente casualizado. Os dados foram analisados utilizando uma análise de variância com medidas repetidas, para a comparação das médias foi utilizado o teste de Tukey ao nível de 5% de probabilidade. A variação no teor de Ca (P 0,05) ocasionou alteração na relação Ca:P da cana-de-açúcar hidrolisada, chegando a relação de 36,46:1 na dose mais elevada de cal (2,0%). Os teores de P, K, Mg, Zn e Cu diminuíram com a elevação da dose de cal (P 0,05). Em relação ao fator tempo, houve um acréscimo na concentração K, Mg e Mn (P 0,05). O tratamento da cana-de-açúcar com cal virgem (CaO) microprocessada aumenta o teor de Ca do volumoso ocasionando um aumento na relação Ca:P. Há presença de Pb na cal virgem, porém abaixo da concentração tóxica para ruminantes.