甘油对大豆分离蛋白/海藻酸钠复合膜热分解的影响

本文采用流延法制备了一系列甘油增塑、与海藻酸钠共混改性的大豆分离蛋白/海藻酸钠复合膜,并利用热重分析方法对这些复合膜的热分解性能进行了考察.热分解实验中,通过改变升温速率,研究甘油含量对大豆分离蛋白/海藻酸钠复合膜热分解性能的影响.从所得到的TGA和DTA曲线可知,大豆分离蛋白/海藻酸钠复合膜的热分解行为可以分为三个较明显的降解阶段.根据失重速率的变化确定热分解反应最剧烈的温度区间为420 ～630K,对此采用Coats-Redfern方法进行了热分解动力学分析,并得出该阶段为一级热分解反应的结论.通过动力学模型,可以计算得到这些复合膜热分解反应的动力学参数,如表观活化能和指前因子.实验结果显示,甘油的加入使复合膜更易热分解；计算也表明热分解活化能随着甘油量的增加而不断下降,降幅可达50％.

Effect of Glycerol on Thermal Decomposition of Soy Protein Isolate-Sodium Alginate Composite Films

A series of new glycerol-plasticized soy protein isolate(SPI) composite films,modified by the incorporation of sodium alginate,were fabricated in this work by using the solution casting method.The thermal decomposition properties of the films thus obtained were examined with a thermogravimetric analyzer.The influence of the glycerol content on the thermal degradation of SPI/SA composite films has been evaluated by means of varying the heating rate of thermal experiments. Based on TGA and DTG results,thermal behavior of the SPI/SA composite films could be clearly separated into three degradation stages.Based on the analysis of the variation in weight loss rate,the main thermal decomposition in the range of 420 ~ 630K was found to be the first order reaction through the Coats-Redfern method.Using certain models,the kinetic parameters like the apparent activation energy and the frequency factor can be calculated for these composite films.Experimental results showed that glycerol added has made the composite films more readily thermally degradable,which is also reflected by the 50%decrease in activation energy with the increase in glycerol content.