羟乙基纤维素填充大豆蛋白塑料的结构和性能

将羟乙基纤维素(HEC)填充大豆分离蛋白(SPI)制备出生物可降解SPI/HEC复合材料(ES),并用X-射线衍射、差示扫描量热法、扫描电镜和拉力测试表征其结构和力学性能。值得关注的是,仅仅加入5%(wt)的HEC即可使复合材料的拉伸强度达到11.74MPa(比纯大豆分离蛋白材料增加了60%),同时其断裂伸长率增加了50%。HEC在共混材料内部因含量的增加,由单分子分散逐渐聚集形成独立的结晶微区,导致增强效果的降低和伸长率的明显下降。当HEC以单分子分散并通过其伸出的侧基嵌入基质时,较强的组分间相互作用实现了材料的同步增强增韧,是提高力学性能的最佳形式。

Structure and Properties of Soy Protein Plastics Filled with Hydroxyethyl Cellulose

The biodegradable composite materials were prepared by filling hydroxyethyl cellulose (HEC) into soy protein isolate (SPI) under mechanical blending with the plasticization of glycerol. The structure and properties of the composite sheets were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and tensile testing. It was worth noting that the tensile strength of the composite material filled with only 5% (wt) HEC reached 11.74 MPa (as much as ca. 0.6-fold over that of pure SPI sheets) while the breaking elongation increased by 0.5 times as well. With an increase of HEC content, the distribution of HEC molecules transferred from the status of single chain to the crystalline domain of aggregates, resulting in the weakening of reinforcing function and the decrease of breaking elongation. It can be concluded that the filling of HEC as simple molecule might produce the optimal mechanical properties for blend materials, and that hydroxyethyl side-group stretching out of cellulose backbone chain and inserted into SPI matrix played a key role in simultaneous reinforcing and toughening as well as strong interaction between components.