Rheological Characterization of Combretum Glutinosum (Habeil) Gum

Rheological properties of Gum Habeil collected during three seasons had been studied. Intrinsic viscosity of aqueous solution of Gum Habeil was calculated by Fedor's equation. At a low concentration of aqueous deacetylated gum solution, the G' (viscoelastic) was appeared higher than G'' (viscosity) at frequency ranged from 1 to 10 Hz, but with increases concentration of deacetylated gum solutions G'' line was trend to appear higher than G' line at low frequency region. However, a crossover of G' and G'' lines was observed as the frequencies increased to 1.26, 3.97, and 9.99 Hz for 1.5, 3, and 5% w/w of gum solutions respectively. The concentrated crude gum dispersions 12.5 and 15% w/w were exhibited viscoelastic behavior, in contrast the 10% w/w of crud gum solution in distilled water appeared G'' higher than G' with the crosslink points at the middle of frequency range. The critical concentration C* of deacetylated gum solutions in deionized water, in sodium hydroxide alone, and in alkali with addition salt were determined to be 2.34, 2.37, and 2.41 g/dl respectively. The effect of temperature on rheological behavior was also studied.