Effect of Different Film-forming Temperature on Physicochemical Properties and Microstructure of Sorghum Straw Powder/Nano-ZnO/Polyvinyl Alcohol Nanocomposite Film

In order to improve the utilization of agricultural and forestry waste and promote the industrial production of new biomass materials, sorghum straw powder (SSP), nano-ZnO, polyvinyl alcohol (PVA) were used as the main film matrix and sorghum straw powder/nano-ZnO/polyvinyl alcohol (SSP/Nano-ZnO/PVA, SNP) nanocomposite films were prepared by blending casting method in this research. The effects of SSP addition and different film-forming temperatures (75, 80, 85, 90, 95 ℃) on the thickness, tensile strength (TS), barrier properties, microstructure, spectral properties and thermal properties of SNP nanocomposite films were investigated. The results showed that the addition of SSP could improve the TS, barrier properties and thermal properties of the SNP nanocomposite films. With the increase of the film-forming temperature, the TS and barrier properties of the SNP nanocomposite films increased first and decreased later. When the film forming temperature was 85 ℃, SNP nanocomposite film exhibited the best comprehensive performance with maximum TS (31.22 MPa) and minimum water vapor transmission coefficient (1.32×10⁻¹² g/(cm·s·Pa)), water soluble (36.41%) and swelling degree (238.41%). The SEM, AFM, FT-IR and TG analyses showed that the SNP nanocomposite film had a smooth surface, dense cross-section, good compatibility between the substrates and good thermal stability, and overall performance (better than other film-forming temperatures of nanocomposite films).