Effect of concentration on rheological properties of acid-hydrolyzed amylopectin solutions

Rheological properties are sensitive to variations in molecular structure a nd they are useful in developing structure-function relationships for syste ms of polysaccharides in solution. Intrinsic viscosities of acid-hydrolyzed Amioca starches in 90% DMSO/10% water were determined using a modified app roach for polyelectrolytes. Double logarithmic plots of specific viscosity, eta(sp). against coil overlap parameter, c[eta], were made and trends in b oth the dilute and concentrated regimes were found to be similar to those s een with other polysaccharides. Dynamic frequency sweeps indicated that all acid-hydrolyzed starches in 90% DMSO/10% water exhibited dilute solution o r liquid-like behavior with G " higher than G'. A contradiction in classifi cation of 6-12% starch dispersions was found with shear tests (concentrated ) and small strain oscillatory tests (dilute). (C) 2000 Elsevier Science Lt d. All rights reserved.