NMR INVESTIGATION OF THE DYNAMIC BEHAVIOR OF GUAR GALACTOMANNAN WATERSOLUTIONS

Proton longitudinal and transverse relaxation times have been measured to examine the concentration dependence of the dynamic behaviour of g uar galactomannan aqueous solutions. Two concentration regimes have be en evidenced from our results, with a limiting concentration separatin g the two regimes at about 3% guar concentration. The T1/T2 ratio indi cates that even bulk water experiences anisotropic motions over the li miting concentration. A comparison is made with T1/T2 ratios evaluated in glucose solutions which do not exhibit any deviation from isotropi c behaviour of bulk water molecules. The results are discussed taking into account topological entanglement interactions between polysacchar ide molecules, according to the current model for the solution behavio ur of guar galactomannan.