- NaCl 0.20 mol/dm³) showed small difference in elution volume, but significant changes in the average molecular weight (Mn and Mw) and polydispersion that, in agree with the values of Huggins constant, present evidences of chitosan aggregates formation in the second solvent.]]>
Resumo: Neste trabalho, duas frações de xilana, denominadas xilana A e xilana B, foram isoladas a partir de sabugos de milho através de três processos diferentes, combinando métodos de extração aquosa, remoção de lipídeos, deslignificação e extração alcalina. Os produtos obtidos durante os processos foram analisados por termogravimetria. A etapa de deslignificação foi responsável por uma acentuada degradação dos polímeros, evidenciada por queda de rendimento e resistência térmica. Os espectros obtidos no infravermelho evidenciaram a ausência de ácidos urônicos na cadeia polimérica. As viscosidades intrínsecas obtidas para a xilana A (56 mL/g) e xilana B (75 mL/g) associadas aos resultados do infravermelho sugerem um número maior de grupos substituintes, constituídos basicamente por resíduos de L-arabinose, para a xilana B. Xilana, hemicelulose, polissacarídeo, deslignificação.
Palavras-chave:
Among the biodegradable polymers, the polysaccharides have been found to be promising carriers for bioactive molecules. From a general standpoint, they present several reactive groups, such as hydroxyl, carboxyl and amine, that can be modified in a number of ways, giving rise to suitable devices for controlled release. In this paper, agarose was submitted to O-acetylation reactions under heterogeneous conditions, using acetic anhydride and pyridine, aiming to observe the effect of acetyl groups on the agarose properties. The products were characterized by Infrared and ¹H NMR spectroscopies. In the range of average acetylation degrees (DA) 0.07-0.48, the polymers presented partial solubility in boiling water and in common organic solvents. The ¹H NMR spectra presented evidences of non-homogeneous acetyl group distribution along the chains, as concluded from the solubility of only one of the fractions with DA<0.09, in boiling water
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.