磷酸化淀粉的疏水化交联及改性机理的研究

为了提高淀粉基塑料膜的降解性能,需要对淀粉进行疏水亲脂化改性。该文以磷酸化交联淀粉为原料,甲氧基硅烷偶联剂KH-570为改性剂,采用干法工艺对交联淀粉进行疏水亲脂化改性。通过四因素二次旋转正交组合试验设计及响应面分析,得出淀粉疏水化改性的回归模型。并利用旋转黏度仪、生物显微镜以及红外光谱仪表征疏水化交联淀粉。结果表明,疏水化改性最佳工艺参数为乙醇浓度为95.70%,KH570用量为1.68%(占淀粉干基),稀释度为2.81%,反应时间为29.61min。疏水化交联淀粉吸水率最小为16.23%,较原淀粉和交联淀粉吸水率分别降低了42.44%和33.2%。随着疏水化改性程度的加深,改性淀粉在液体石蜡有机介质中的分散性明显增强;颗粒形态由疏松态向串状葡萄球团聚态转变;在交联淀粉脱水葡萄糖单元羟基上引入了甲氧基硅烷偶联剂KH570的长链基团。

Hydrophobic coupling cross-linked starch phosphorylation and mechanism of modification

In order to increase degradability and mechanical property of starch-based plastics films,it is necessary that starch is modified by hydrophobic and lipophilic treatment.With cross-linked starch(CST)as a raw material and the organic silane coupling agents KH570 as a modifier,dry method was used to improve the hydrophobic and lipophilic property of cross-linked starch.By using four-factor quadratics rotary orthogonal combination experiment design method and response surface analysis,a regression model of hydrophobic modified starch was obtained.The hydrophobic modified starch was characterized by rotational viscometer,biomicroscopy and infrared spectrometer.The results indicate that the optimized processing parameters of hydrophobic modification are alcohol concentration 95.70%, amount of KH570 1.68%(dry starch base),dilution degree 2.81%,and reaction time 29.61 min.The minimum capacity of water adsorption of hydrophobic coupling cross-linked starch(KCST)is 16.23%,the adsorption rate decreases by 42.44%and 33.2%compared with nature starch and cross-linked starch(CST).With the deepening of hydrophobic modification,the dispensability of modified starch in organic solvent liquid paraffin is markedly enhanced.The particle shape changes from rarefaction to cluster grape ball agglomeration state.The long chain group of methoxyl silane coupling agents KH570 is linked with the anhydrous glucose units of the cross-linked starch.