Fahd A. Tirkistani

Thermal analysis of some chitosan Schiff bases

Reactions of chitosan with aromatic aldehydes gave Schiff base polymers. The products were characterized and identified using microanalysis and IR spectroscopy. Thermal analyses of the polymers showed that they are less stable than chitosan itself.

Thermal analysis of chitosan modified by cyclic oxygenated compounds

Reactions of chitosan with cyclic oxygenated compounds were carried out and the products characterized using microanalysis and IR spectroscopy. Thermal analysis of the polymers formed showed a decrease in stability, attributed to the removal of the free amino group.

Kinetics and mechanism of oxidation of chondroitin-4-sulfate polysaccharide by chromic acid in aqueous perchlorate solutions

The kinetics of chromic acid oxidation of chondroitin-4-sulfate polysaccharide as sulfated carbohydrates at a constant ionic strength of 4.0 mol dm(-3) has been investigated, spectrophotometrically. The reaction kinetics showed a first-order dependence in chromic acid and fractional-first-order kinetics with respect to the chondroitin-4-sulfate concentration. The influence of [H(+)] on the reaction rates showed that the oxidation process is acid-catalyzed. Added Mn(2+) ions indicated the formation of Cr(IV) as intermediate species. A kinetic evidence for formation of 1:1 intermediate complex was revealed. The kinetic parameters have been evaluated and a tentative reaction mechanism in good consistent with the kinetic results obtained is discussed.

Thermal analysis of polyacrylic acid modified by some glucosamine derivatives

Polymerization of acrylic acid in the presence of N-acetylglucosamine and glucosamine hydrochloride was carried out and the products were characterized using IR spectroscopy. A mechanism for the formation of the modified polymers was suggested. Thermal analyses of the polymers formed were studied. It was found that the polymers containing free amino groups are more stable than other polymers.