Some aspects of acetylation of untreated and mercerized sisal cellulose

Journal of the Brazilian Chemical Society

Gabriela T. Ciacco²  Daniella Lury Morgado²  Elisabete Frollini²  Shirley Possidonio¹  Omar A. El Seoud¹ 

[1] ,University of São Paulo Institute of Chemistry São Carlos SP ,Brazil

关键词: cellulose aggregation;    cellulose acetylation;    degree of cellulose acetate substitution;    LiCl/DMAc;   

DOI  :  10.1590/S0103-50532010000100012

来源: SciELO

【 摘 要 】

We report here on some aspects of the acetylation in LiCl/N,N-dimethylacetamide, DMAc, of untreated and mercerized sisal cellulose, hereafter designated as sisal and M-sisal, respectively. Fiber mercerization by NaOH solution has resulted in the following changes: 29.9% decrease in the index of crystallinity; 16.2% decrease in the degree of polymerization and 9.3% increase in α-cellulose content. A light scattering study of solutions of sisal, M-sisal, microcrystalline and cotton celluloses in LiCl/DMAc has shown that they are present as aggregates, with (an apparent) average aggregation numbers of 5.2, 3.2, 9.8, and 35.3, respectively. The presence of these aggregates affects the accessibility of cellulose during its functionalization. A study of the evolution of the degree of substitution, DS, of cellulose acetate as a function of reaction time showed an increase up to 5 h, followed by a decrease at 7 h. Possible reasons for this decrease are discussed. As expected, M-sisal gave a higher DS that its untreated counterpart.

【 授权许可】

CC BY   
 All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License