Chitosan is a linear polysaccharide obtained from the deacetylation of chitin. The physico-chemical properties of chitosan dependent on the average degree of acetylation (<img border=0 id="_x0000_i1029" src="../../../../img/revistas/po/v13n4/19880x8.gif" align=absmiddle>) and of the average molar mass (<img border=0 id="_x0000_i1030" src="../../../../img/revistas/po/v13n4/19880x2.gif" align=absmiddle>). Several applications of chitosan have been proposed in the literature, mainly in water treatment, cosmetic and drug manufacturing, food additives, semipermeable membranes and development of biomaterials. In this work, three commercial chitosan samples were characterized by proton nuclear magnetic resonance (¹H NMR), infrared spectroscopy (IR), conductimetric titration and thermal analysis (TG and DSC) in order to compare commercial chitosans from different supplies. The average viscosimetric molecular weight Mv was estimated from the intrinsic viscosity. The results confirmed remarkable differences in relation to the mean degree of acetylation (<img border=0 id="_x0000_i1031" src="../../../../img/revistas/po/v13n4/19880x8.gif" align=absmiddle>) (or desacetylation, <img border=0 id="_x0000_i1032" src="../../../../img/revistas/po/v13n4/19880x3.gif" align=absmiddle>). The thermal analysis data permitted to follow the dehydration, decomposition, and glass transition temperature (Tg).
Chitosan; medium degree of acetylation; thermogravimetry; DSC
