Effect of the Process Parameters of CNC-Corn Starch Composite Oxidation on the Rheological Properties of Its Composite Film-Forming Solution

In this paper, corn starch was oxidized by NaClO with the assistance of cellulose nanocrystals, and then mixed with polyvinyl alcohol and glycerol to prepare film-forming solution. The effect of corn starch concentration (3.0%, 5.0%, 8.0% and 10.0%), oxidation and film-forming liquid components (PVA 30.0%, 40.0%, 50.0%, 60.0%, 70.0% and 80.0%) on the rheological properties of the composite forming solution were investigated. The results indicated that oxidation could lead the reduction of viscosity, and the lowest was 0.08 Pa·s.The increase of oxidized starch concentration could improve viscosity, shear stress, thixotropy and viscoelasticity of the oxidized starch paste and the film-forming solution, however, its stability was lowered. The viscosity and stability of the oxidized starch paste and the film forming solution were good at 5.0% of the oxidized starch concentration. The increase of PVA dosage could improve viscosity, shear stress and viscoelasticity of the film-forming solution. the viscosity and viscoelasticity of film-forming solution reached maximum at 60.0% of PVA dosage, and the maximum viscosity was 9.9 Pa·s.Starch paste and film-forming solution showed shear-thinning property and positive thixotropy, and their rheological features could be fitted by Ostwald-de-Waele model.