Feasibility of ramie fibers as raw material for the isolation of nanofibrillated cellulose.

In this study, a strategy was adopted to enhance the use of ramie fibers as raw material for isolation of cellulose nanofibers (CNFs). Ramie pulp was produced by alkaline organosolv followed by bleaching. CNFs were produced by mechanical defibrillation, and films were fabricated via casting. Effects of number of passes in the mechanical grinding on physical and mechanical properties of CNF films were comprehensively studied. Potential of ramie fibers was proved by fabricating homogeneous nanofibers with average thickness of 8.72 nm, which led to CNF films with dense and non-porous networks, and crystallinity index of 76-78%. Tensile strength (42-82 MPa) and dynamic mechanical (9-11 GPa) performance were good only for less severe mechanical defibrillation. Lower solubility (1.85-2.43%). and activity (0.69) in water, and outstanding barrier properties against water vapor and oxygen make ramie suitable for more sustainable extraction of cellulose nanofibers and production of CNF films for diverse applications.

Histochemical analysis of stem and fiber of ramie (Boehmeria nivea (L.) Gaud var. Murakami) / Análises histoquímicas do caule e das fibras do rami (Boehmeria nivea (L.) Gaud var. Murakami)

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