Molten imidazole – a starch solvent

Abstract

Molten imidazole was found to be an efficient, stable and non-derivatising solvent for starch. Clear solutions with up to 20 wt% starch are accessible in molten imidazole without any pretreatment. Solutions with a starch content of 10 wt% generate dynamic viscosity values between 20 Pa s (Hylon VII) and 70 Pa s (potato starch). In general, Newtonian behavior of the solutions is revealed by rheological studies. Organic liquids and water can be used as co-solvents with up to 50 wt% without precipitation. Such ternary starch solutions exhibit increased viscosity. Dissolution of starch in imidazole causes some polymer degradation but no change in the chemical structure of the macromolecule as detected by means of NMR- and IR spectroscopy.