Abstract: Polymer blends were prepared via thermo-pressing mixtures of soy protein isolate(SPI) and poly (vinyl alcohol) (PVA) using glycerol as a plasticizer. The structure, morphology, and properties of the blends were investigated using X-ray diffraction, dynamic mechanical analyzer, differential scanning calorimetry analyzer, universal electronic tensile testing machine, and scanning electron microscopy. Phase separation was observed between glycerol and SPI forming glycerol-rich and protein-rich domains. The addition of PVA significantly damaged the crystalline structure of SPI in glycerol-rich domain, and increased its glass transition temperature. When the content of PVA was 1 phr, the tensile strength of SPI/PVA increased by 41.5 %, and the 24 h water absorption of SPI/PVA decreased from 134.86 % to 77.38 %, based on neat SPI.

Key words: soy protein isolate, poly (vinyl alcohol), structure, mechanical property, water absorption ability