Rheology of nano ZnO - Hydroxypropyl Methylcellulose (HPMC) based suspensions and structural properties of resulting films

Effect of polyethylene glycol (PEG) and ZnO nanoparticles concentration on rheological properties of the hydroxypropyl methylcellulose (HPMC) based film forming suspensions (FFS) and, on the structural properties of the resulting films were characterized. Rheological properties of FFS were not significantly affected by PEG concentration and ZnO NPs incorporation. Intrinsic viscosity [eta] of aqueous HPMC solution obtained from extrapolation of Huggins and Kraemer plot was 0.115-0.118 (L/g). Coating thickness calculated as a function of coating solution viscosity, concentration and draining time for strawberry coating was 1.26-1.49 mu m. Tensile strength (TS) of HPMC film decreased while water vapor permeability (WVP) increased with increasing PEG concentration. Elongation at break (%E) increased up to 25% PEG concentration and decreased afterward. Incorporation of ZnO NPs improved the tensile strength and barrier properties of HPMC film. Relaxation per-centage and stress decay rate increased with increasing plasticizer concentration while decreased with incor-poration of ZnO NPs.