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Structural modifications of cellulose in heterogeneous acetylation process

N. OLARU1,* , D. CIOLACU1, D. TAMPU1, L. OLARU1

Affiliation

  1. Institute of Macromolecular Chemistry “Petru Poni” Aleea Grigore Ghica-Voda 41 A, Iasi – 700487, Romania

Abstract

Three cellulosic materials with crystalline structures of cellulose I, cellulose II and mixture of cellulose I and III, respectively, are acetylated in a heterogeneous system consisting of a mixture of acetic acid and toluene in order to decrease their hydrophilic character. Different degrees of acetylation are achieved by carrying out the process for various times of reaction. The variation of water affinity of the acetylated fibres estimated from DSC thermograms is studied in relation with the extent of acetylation and with the structural modification of cellulose fibres as revealed by X-ray and FTIR analyses. It was found that two factors are involved in decreasing the hydrophilic character of the studied samples: the change in supramolecular structure and the degree of chemical modification. At lower degrees of acetylation, the reducing of ordered regions in cellulosic material increases the water affinity, while at higher extents of modification, though the decrystallization is more pronounced, water affinity is reduced because of the lower number of free OH groups on the cellulose chain. It was also established that although a decrease of crystallinity is produced for all the studied celluloses, the crystalline forms of the starting celluloses are maintained..

Keywords

Cellulose, Heterogeneous acetylation, Supramolecular structure, X-ray, DSC, FTIR.

Submitted at: Oct. 8, 2007
Accepted at: Dec. 7, 2007

Citation

N. OLARU, D. CIOLACU, D. TAMPU, L. OLARU, Structural modifications of cellulose in heterogeneous acetylation process, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 12, pp. 3917-3920 (2007)