Rheological and gel properties of hydroxypropyl methylcellulose/hydroxypropyl starch blends

This work focuses on the study of rheological and gel properties of hydroxypropyl methylcellulose (HPMC)/hydroxypropyl starch (HPS) blends. It was found that both rheological properties in solution and gel behaviors in hydrogel of the blends depended on polymer/solvent concentration, HPMC/HPS ratio, and temperature. At higher temperature, all the blending samples showed hydrogel behavior, while at lower temperature, the suspensions with higher HPS ratio displayed hydrogel-like behavior but the gels were able to be destroyed at higher frequencies. With an increase of the HPS ratio, the fluid behavior index deceases, meaning the solution shows more obvious pseudoplastic behavior. However, the fluid consistency index increases, meaning that viscosity increases with increase of HPS content. The strength of HPMC gel was weakened by additional of HPS at higher temperature, while the HPS gel was weakened by addition of HPMC at lower temperatures. Viscosities of both HPMC and HPS were balanced by the blending at different temperatures since one is thermal and other is cool gel, which improves the processability for many applications.