不同甲酰胺含量下大豆蛋白塑料的性能和结构

将甲酰胺按不同比例与大豆蛋白质混合,经模压成型制成大豆蛋白塑料,并采用材料实验机、热重分析仪、动态力学热分析仪、红外光谱仪和扫描电镜研究了塑料的性能、结构和形态.结果表明:当甲酰胺的含量(质量分数)为20%时,大豆蛋白塑料具有最大的断裂伸长率,为269.66%,比纯大豆蛋白塑料提高了76倍;甲酰胺含量为20%的大豆蛋白塑料的热失重曲线中甲酰胺最大质量损失速率所对应的温度远高于甲酰胺的沸点;甲酰胺增塑塑料的吸水率和玻璃化转变温度随甲酰胺含量的增加而降低,而损耗峰峰高则呈增加趋势;红外光谱表明甲酰胺增塑剂与大豆蛋白质分子之间发生了氢键相互作用,并破坏了蛋白质之间的氢键作用;扫描电镜实验证实甲酰胺作为增塑剂可显著改善纯大豆蛋白塑料的内部组织结构,提高塑料的韧性.

Properties and Structure of Soy Protein Plastic with Different Formamide Contents

Soy protein and formamide were mixed at different ratios and were hot press-molded to produce soy protein plastic.The properties,structure and morphology of the plastic were then investigated by means of tensile test,thermogravimetric analysis,dynamic mechanical thermal analysis,Fourier-transform infrared spectroscopy,and scanning electron microscopy.The results show that(1) the soy protein plastic with a formamide content(mass fraction) of 20% has a maximum elongation of 269.66%,which is 77 times that of pure soy protein plastic;(2) the temperature for the maximum mass loss of the plastic with 20% of formamide is much higher than the boiling point of pure formamide;and(3) the water absorption and glass transition temperature of the formamide-plasticized plastic decrease with the increase in formamide content,while the height of loss peak increases.It is also indicated by FTIR that there exist hydrogen bonds between the plasticizer and the soy proteins,which breaks the hydrogen bonds among the protein molecules.Furthermore,the SEM results prove that the introduction of formamide can greatly improve the microstructure and flexibility of soy protein plastic.