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Cellulose nanocrystals from fibers of Macauba (Acrocomia Aculeata) and Gravata (Bromelia Balansae) from Brazilian Pantanal. Repositório Alice
CORRÊA, A. C.; CARMONA, V. B.; SIMÃO, J. A.; GALVANI, F.; MARCONCINI, J. M.; MATTOSO, L. H. C..
Cellulose nanocrystals (CNC) were obtained from macauba and gravata fibers. Macauba (or Bocaiuva) is a palm tree found throughout most of Brazil and Gravata is an abundant kind of bromeliab with 1-2m long leaves, found in Brazilian Pantanal and Cerrado. The raw fibers of both fibers were mercerized with NaOH solutions and bleached; they were then submitted to acid hydrolysis using H2SO4 at 45 ?C, varying the hydrolysis time from 15 up to 75 min. The fibers were analyzed by X-ray diffraction (XRD), FTIR Spectroscopy, scanning electron microscopy (SEM) and thermal stability by thermogravimetric analysis (TG). XRD patterns did not present changes in the crystal structure of cellulose after mercerization, but it was observed a decrease of hemicellulose and...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Celulose; Macaúba; Fibra Vegetal; Gravata; Cellulose; Nanocrystals; Plant fibers; Acrocomia.
Ano: 2019 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1114101
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Chemically modified cellulose nanocrystals as polyanion for preparation of polyelectrolyte complex. Repositório Alice
VASCONCELOS, N. F.; FEITOSA, J. P. A.; ANDRADE, F. K.; MIRANDA, M. A. R.; SASAKI, J. M.; MORAIS, J. P. S.; SILVA, L. M. A. e; CANUTO, K. M.; ROSA, M. de F..
Bacterial cellulose nanocrystals (BCNCs) have hydrophilic surfaces due to hydroxyl groups but are water-insoluble. The carboxymethylation improves the solubility of cellulose in polar media through the insertion of carboxymethyl groups. This study aims to evaluate the use of two different alcoholic solvents in the carboxymethylation reaction of BCNCs: ethanol and isopropanol. BCNCs were obtained under two hydrolysis conditions: sulfuric acid (BCNC-S) and combination of sulfuric and hydrochloric acids (BCNC-S/Cl). Two techniques (NMR and titration) were used to determine the degree of substitution (DS) values. Carboxymethylation of BCNC-S/Cl led to high DS compared to BCNC-S and the use of isopropanol promoted an even greater DS. The thermal properties were...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Carboxymethylation; Polyelectrolytic complexes; Hydrolysis; Nanocrystals; Chitosan.
Ano: 2019 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1118682
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