Soy Protein Plastics Strengthened with Star-like Lignin DerivativesWEI Ming~1,HUANG Jin~(1,2),AI Fu-jin~1,FAN Li-hong~1,ZHENG Hua~1 (1.School of Chemical Engineering,Wuhan University of Technology,Wuhan 430070,China;2.State Key Laboratory of Pulp and Paper Engineering,South China University of Technology,Guangzhou 510640,China)Biodegradable soy protein(SPI) plastics were compounded with star-like hydroxypropyl lignin(HL) to produce SPI/HL composite sheets with good mechanical performance.The structure and properties of composite materials were characterized by X-ray diffraction,differential scanning calorimetry,scanning electron microscopy,transmission electron microscopy and tensile test.It was worth noting that adding only 2% HL resulted in tensile strength of 16.8 MPa as much as 2.3-fold over that of pure SPI sheets without the elongation loss.As the HL content increased,HL can self-aggregate as supramolecular domain at nano scale,and the stronger interactions between HL and glycerol resulted in the absence of glycerol in SPI matrix.Thus,although the strength of composite materials increased,the elongation sharply decreased.It can be concluded that the filling of HL as simple molecule into SPI matrix would provide the optimal mechanical properties in this system by the stronger ability of stretching chains to adhere hybrid components in SPI matrix.soy protein;lignin;blend;strengthening;supramolecular structure