An evaluation of hydration and thermal decomposition of HAlg and its sodium salt is described using thermogravimetry (TG) and differential scanning calorimetry (DSC). TG curves in N2 and air, were obtained for alginic acid showed two decomposition steps attributed to loss of water and polymer decomposition respectively. The sodium alginate decomposed in three steps. The first attributed to water loss, followed by the formation of a carbonaceous residue and finally the Na2CO3. DSC curves presented peaks in agreement with the TG data. In the IR alginic acid presented bands at 1730 and 1631 cm-1, while sodium alginate presented a doublet at 1614 e 1431 cm-1, evidencing the presence of salified carboxyl groups.

Chitosan is a linear polysaccharide obtained from the deacetylation of chitin. The physico-chemical properties of chitosan dependent on the average degree of acetylation ( DA ) and of the average molar mass ( M ). 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 ( 1 H 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 M v was estimated from the intrinsic viscosity. The results confirmed remarkable differences in relation to the mean degree of acetylation ( DA ) (or desacetylation, DD ). The thermal analysis data permitted to follow the dehydration, decomposition, and glass transition temperature (Tg).

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An evaluation of hydration and thermal decomposition of HAlg and its sodium salt isdescribed using thermogravimetry (TG) and differential scanning calorimetry (DSC). TG curves inN 2 and air, were obtained for alginic acid showed two decomposition steps attributed to loss of waterand polymer decomposition respectively. The sodium alginate decomposed in three steps. The firstattributed to water loss, followed by the formation of a carbonaceous residue and finally the Na 2 CO 3 .DSC curves presented peaks in agreement with the TG data. In the IR alginic acid presented bands at1730 and 1631 cm -1 , while sodium alginate presented a doublet at 1614 e 1431 cm -1 , evidencing thepresence of salified carboxyl groups.