Effects of molecule weight on the liquid adsorption, surface free energy and rheological properties of dextran

Abstract

The effects of molecular weight, M_W, on the liquid adsorption, surface free energy and rheological properties of dextran were systemically studied. Results showed that the dextran can adsorb both the polar and non-polar liquids, while the non-polar diiodomethane was greatly adsorbed and the non-polar hexane was small adsorbed. This is because of the total surface free energy of dextran dominated by the non-polar Lifshitz–van der Waals interaction component, LW. Dextran is strongly in the Lewis base and weakly in the Lewis acid and the former was increased with the M_W increase and the latter was varied on the contrary. Two intrinsic rheological parameters, e.g. [n] and [k], were deduced from the normal flow behavior index, n, and the consistency index, k, correspondingly and found to reduce with the increase of all the surface free energy components except the Lewis base component for dextran. The [n] and [k] can describe the rheological properties as the normal n and k, however, unlike the normal parameters due to ignoring the variety of concentration.

Keywords:

• Dextran
• molecular weight
• liquid adsorption
• surface free energy
• rheological property