RESUMEN

Graphene oxide (GO) incorporation in natural fiber composites has recently defined a novel class of materials with enhanced properties for applications, including ballistic armors. In the present work, the performance of a 0.5 vol % GO-incorporated epoxy matrix composite reinforced with 30 vol % fabric made of ramie fibers was investigated by stand-alone ballistic tests against the threat of a 0.22 lead projectile. Composite characterization was also performed by Fourier-transform infrared spectroscopy, thermal analysis and X-ray diffraction. Ballistic tests disclosed an absorbed energy of 130 J, which is higher than those reported for other natural fabrics epoxy composite, 74-97 J, as well as plain Kevlar (synthetic aramid fabric), 100 J, with the same thickness. This is attributed to the improved adhesion between the ramie fabric and the composite matrix due to the GO-incorporated epoxy. The onset of thermal degradation above 300 °C indicates a relatively higher working temperature as compared to common natural fiber polymer composites. DSC peaks show a low amount of heat absorbed or release due to glass transition endothermic (113-121 °C) and volatile release exothermic (~132 °C) events. The 1030 cm-1 prominent FTIR band, associated with GO bands between epoxy chains and graphene oxide groups, suggested an effective distribution of GO throughout the composite matrix. As expected, XRD of the 30 vol % ramie fabric-reinforced GO-incorporated epoxy matrix composite confirmed the displacement of the (0 0 1) peak of GO by 8° due to intercalation of epoxy chains into the spacing between GO layers. By improving the adhesion to the ramie fabric and enhancing the thermal stability of the epoxy matrix, as well as by superior absorption energy from projectile penetration, the GO may contribute to the composite effective ballistic performance.

RESUMEN

The main objective of this work was to investigate the effect of hybridization on the mechanical and thermal properties of intralaminar natural fiber-reinforced hybrid composites based on sisal. Ramie, sisal and curauá fibers were selected as natural fiber reinforcements for the epoxy matrix based composites, which were produced by the hand lay-up technique. Tensile, flexural and impact tests were carried out according to American society for testing and materials (ASTM) standards to characterize the hybrid composites, while differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to evaluate the thermal properties. It was found that the mechanical properties are improved by hybridization of sisal based composites. The thermal analysis showed that the hybridization did not significantly affect the thermal stability of the composites. A scanning electron microscopy (SEM) was used to examine the fracture surface of the tested specimens. The SEM images showed a brittle fracture of the matrix and fiber breakage near the matrix.

RESUMEN

Analyzes of samples of stem and fiber Boehmeria nivea var. Murakami were performed to increase information on the plant and disseminate its multiple possibilities of use. The histochemical analyzes with dyes and reagents showed the presence of lignified, suberous and cutinized cell walls with Safranin in the xylem region. The presence of pectin-cellulose with Astra Blue was confirmed in the regions of fiber bundles (cortex). In all regions of the stem were identified substances such as fat and mucilage with Methylene Blue evidencing high concentrations in the regions of fiber bundles and bark (violet blue). By means of Lugol (dark brown) starches were identified in several parts of the stem with concentrations in the xylem and epidermal regions. Through analyzes by EDS it was possible to identify F, Mg, Al, Si, K and Ca with predominance of K. In the chemical analyzes of the fibers were found 71.75 of cellulose, 12.11 of hemicelluloses, 1.06 of lignin and 1.70% of ashes. The percentages of extractives soluble in hot and cold water were 5.28 and 3.12% respectively, for Ethanol-Toluene was 8.55 and NaOH (1%) 27.27%. Histochemical analyzes revealed important characteristics of the fiber and stem contributing with better knowledge of the species.

Análises de amostras de caule e de fibras Boehmeria nivea var. ‘Murakami’ foram realizadas para aumentar o conhecimento da planta e difundir suas múltiplas possibilidades de uso. As análises histoquímicas com corantes e reagentes mostraram paredes celulares lignificadas, suberosas e cutinizadas com Safranina na região do xilema. Confirmou-se a presença de pectocelulose com Azul de Astra nas regiões de feixes de fibras (córtex). Em todas as regiões do caule, foram identificadas substâncias como gordura e mucilagem com Azul de Metileno, evidenciando elevadas concentrações nas regiões dos feixes de fibras e da casca (azul violeta). Por meio de Lugol (marrom escuro), foram identificados amidos em várias partes do caule com concentrações nas regiões do xilema e da epiderme. Por meio de análises de EDS, foram identificados F, Mg, Al, Si, K e Ca, com predominância do K. Nas análises químicas das fibras, foram encontrados 71,09 de celulose, 12,11 de hemiceluloses, 1,06 de lignina e 1,70% de cinzas. As porcentagens de extrativos solúveis em água quente e fria foram de 5,28 e 3,12%, respectivamente. Para o Etanol-Tolueno, foi 8,55 e para o NaOH (1%), 27,27%. As análises histoquímicas revelaram importantes características das fibras e do caule, contribuindo com melhores conhecimentos da espécie

RESUMEN

Analyzes of samples of stem and fiber Boehmeria nivea var. Murakami were performed to increase information on the plant and disseminate its multiple possibilities of use. The histochemical analyzes with dyes and reagents showed the presence of lignified, suberous and cutinized cell walls with Safranin in the xylem region. The presence of pectin-cellulose with Astra Blue was confirmed in the regions of fiber bundles (cortex). In all regions of the stem were identified substances such as fat and mucilage with Methylene Blue evidencing high concentrations in the regions of fiber bundles and bark (violet blue). By means of Lugol (dark brown) starches were identified in several parts of the stem with concentrations in the xylem and epidermal regions. Through analyzes by EDS it was possible to identify F, Mg, Al, Si, K and Ca with predominance of K. In the chemical analyzes of the fibers were found 71.75 of cellulose, 12.11 of hemicelluloses, 1.06 of lignin and 1.70% of ashes. The percentages of extractives soluble in hot and cold water were 5.28 and 3.12% respectively, for Ethanol-Toluene was 8.55 and NaOH (1%) 27.27%. Histochemical analyzes revealed important characteristics of the fiber and stem contributing with better knowledge of the species.(AU)

Análises de amostras de caule e de fibras Boehmeria nivea var. ‘Murakami foram realizadas para aumentar o conhecimento da planta e difundir suas múltiplas possibilidades de uso. As análises histoquímicas com corantes e reagentes mostraram paredes celulares lignificadas, suberosas e cutinizadas com Safranina na região do xilema. Confirmou-se a presença de pectocelulose com Azul de Astra nas regiões de feixes de fibras (córtex). Em todas as regiões do caule, foram identificadas substâncias como gordura e mucilagem com Azul de Metileno, evidenciando elevadas concentrações nas regiões dos feixes de fibras e da casca (azul violeta). Por meio de Lugol (marrom escuro), foram identificados amidos em várias partes do caule com concentrações nas regiões do xilema e da epiderme. Por meio de análises de EDS, foram identificados F, Mg, Al, Si, K e Ca, com predominância do K. Nas análises químicas das fibras, foram encontrados 71,09 de celulose, 12,11 de hemiceluloses, 1,06 de lignina e 1,70% de cinzas. As porcentagens de extrativos solúveis em água quente e fria foram de 5,28 e 3,12%, respectivamente. Para o Etanol-Tolueno, foi 8,55 e para o NaOH (1%), 27,27%. As análises histoquímicas revelaram importantes características das fibras e do caule, contribuindo com melhores conhecimentos da espécie(AU)

RESUMEN

Two trials were conducted at the Seção de Ovinos e Caprinos, in the Instituto de Zootecnia, Nova Odessa, Estado de São Paulo, with the objective to measure the viability and levels of dried ramie residue to feeding goats. In the first trial 8 milk goats of the anglonubian breed were randomized in a 4x4 latin square design. Dried ramie residue was included in four levels in substitution of pangola grass hay: 0, 25, 50 and 75%, considered as dry matter in the roughage. The second trial was a completely randomized design with 16 male kids averaging 180 days of age receiving four levels of dried ramie residue in substitution to pangola grass hay: 0, 34, 66 and 100%. Weight gain and daily consumption of dry matter, crude fiber, crude protein and gross energy did not differed statistically in both trials (P >0.05). The same was not true with milk production in trial I. It was observed the highest milk production at 29% level of dried ramie residue in roughage (P 0.007). The cost of feeding was lower at increasing dried ramie residue levels due to lower levels of protein source as soybean meal in the diets.

Foram conduzidos dois ensaios na Seção de Ovinos e Caprinos, do Instituto de Zootecnia, em Nova Odessa, SP, com o objetivo de verificar a possibilidade e o nível mais adequado de utilização do resíduo da desfibragem do rami, seco ao sol, na alimentação de caprinos. No primeiro ensaio foram utilizadas 8 cabras anglonubianas, em lactação, em esquema de quadrado latino 4 x 4, testando a substituição do feno de capim pangola pelo resíduo da desfibragem do rami, em níveis de 0,25,50 e 75% em termos de matéria seca (MS) do volumoso. No segundo ensaio, foram utilizados 16 caprinos machos, com 180 dias de idade, usando o delineamento inteiramente ao acaso, testando a substituição do feno de pangola pelo resíduo da desfibragem do rami nos níveis de 0, 34, 66 e 100%, em termos de volumoso. Os dados de ganho de peso e ingestão de MS, proteína, fibra e energia bruta dos tratamentos, não diferiram (P> 0,05) em nenhum dos ensaios, já a produção de leite variou de forma significativa (P 0,007), observando-se um melhor desempenho nos níveis de 29% de substituição. As dietas com inclusão do subproduto apresentaram menor custo que a dieta testemunha, em razão da menor necessidade de uso de fontes de proteína no concentrado.

RESUMEN

Two trials were conducted at the Seção de Ovinos e Caprinos, in the Instituto de Zootecnia, Nova Odessa, Estado de São Paulo, with the objective to measure the viability and levels of dried ramie residue to feeding goats. In the first trial 8 milk goats of the anglonubian breed were randomized in a 4x4 latin square design. Dried ramie residue was included in four levels in substitution of pangola grass hay: 0, 25, 50 and 75%, considered as dry matter in the roughage. The second trial was a completely randomized design with 16 male kids averaging 180 days of age receiving four levels of dried ramie residue in substitution to pangola grass hay: 0, 34, 66 and 100%. Weight gain and daily consumption of dry matter, crude fiber, crude protein and gross energy did not differed statistically in both trials (P >0.05). The same was not true with milk production in trial I. It was observed the highest milk production at 29% level of dried ramie residue in roughage (P 0.007). The cost of feeding was lower at increasing dried ramie residue levels due to lower levels of protein source as soybean meal in the diets.

Foram conduzidos dois ensaios na Seção de Ovinos e Caprinos, do Instituto de Zootecnia, em Nova Odessa, SP, com o objetivo de verificar a possibilidade e o nível mais adequado de utilização do resíduo da desfibragem do rami, seco ao sol, na alimentação de caprinos. No primeiro ensaio foram utilizadas 8 cabras anglonubianas, em lactação, em esquema de quadrado latino 4 x 4, testando a substituição do feno de capim pangola pelo resíduo da desfibragem do rami, em níveis de 0,25,50 e 75% em termos de matéria seca (MS) do volumoso. No segundo ensaio, foram utilizados 16 caprinos machos, com 180 dias de idade, usando o delineamento inteiramente ao acaso, testando a substituição do feno de pangola pelo resíduo da desfibragem do rami nos níveis de 0, 34, 66 e 100%, em termos de volumoso. Os dados de ganho de peso e ingestão de MS, proteína, fibra e energia bruta dos tratamentos, não diferiram (P> 0,05) em nenhum dos ensaios, já a produção de leite variou de forma significativa (P 0,007), observando-se um melhor desempenho nos níveis de 29% de substituição. As dietas com inclusão do subproduto apresentaram menor custo que a dieta testemunha, em razão da menor necessidade de uso de fontes de proteína no concentrado.