Effect of Plasticizer Content on the Structure and Properties of SPI/MA-g-PBAT Blend Films

Soy protein isolate (SPI) has the advantages of low cost, easy processing, stable performance and so on. However, the processing temperature of SPI is high, the processed products are hard and brittle with high water absorption capacity, so it is necessary to modify the soybean protein during processing. Small molecule plasticizer is commonly used globally to plasticize and modify soybean protein. Different plasticizer content has different plasticizing effect on protein, and the properties of materials prepared will also vary greatly. The plasticizer can affect the viscosity of the blends morphology and properties by changing the viscosity of protein phase. In this work, glycerol with the excellent plasticizing effect was selected as plasticizer, and SPI was plasticized with glycerol of different contents, and then the plasticized SPI was blended with poly (butylene adipate-co-terephthalate)(PBAT) to prepare biodegradable blend materials. The influence of plasticizer content on the structure and properties of the blends was explored by observing the microstructure, mechanical and thermal properties of the blends. The results showed that with the increase of glycerol content, the crystallization temperature and melting temperature of the blend system increased, the chain segment was easier to move, and the glass transition temperature(Tg) decreased. At the same time, the viscosity of the blending system decreases, which improves the processing fluidity of the system.