Rheology of film-forming solutions and physical properties of tara gum film reinforced with polyvinyl alcohol (PVA)

Abstract Tara gum (TG)/polyvinyl alcohol (PVA) blend films were prepared by a casting method. The films were characterized by Fourier transform-infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and thermogravimetric analysis. The rheology properties of the film-forming solutions were also analyzed. The FTIR results showed hydrogen bonds formed between the two types molecules. The increased crystallinity of the films was illustrated by XRD analysis. The addition of PVA had no obvious influence on the thermal stability of the films. The viscosity measurements revealed that the blended film-forming solution exhibited a shear-thinning behavior and the dynamic tests confirmed the addition of PVA enhanced the elastic behavior. The mechanical, hydrophobic, barrier and transparency properties of films with different ratios of TG/PVA were evaluated. It was found that the tensile strength increased from 20.71 MPa to 44.74 MPa and that the contact angle increased from 55.95° to 90.0° with increasing ratio of TG/PVA from 90/10 to 70/30. The barrier properties (including oxygen permeability, water vapor permeability, and UV barrier ability) were also enhanced with the addition of PVA. Therefore, the combination of TG and PVA could produce a good blend film for use in film-packaging industries.