微波辅助甲基淀粉的制备及产物热性能表征

Microwave-assisted methylation of starch and thermal performance of methylated starch

采用微波辐射的方法,强化了淀粉的活化及与碳酸二甲酯的甲基化反应过程,考察了微波作用时间、无机盐种类、用量等因素对淀粉甲基化反应过程的影响,并对甲基淀粉热性能进行了表征。结果表明,当m(Starch)∶m(NaCl)∶m[(CH3O)2CO]=10∶4∶125、微波辐射13 min时,甲基淀粉的甲氧基含量达8.1%(相当于甲基淀粉的取代度为0.43),反应程度明显提高,反应时间大幅缩短,但与原淀粉相比,高度甲基化的淀粉热稳定性有明显下降。

Microwave irradiation was used to reinforce the activation and methylation process of starch with dimethyl carbonate.The effects of microwave irradiation time,inorganic salt and its dosage on the methylation process were investigated,and the thermal performance of methylated starch was characterized.The results showed that the methoxyl content of methylated starch was up to 8.1%（the degree of substitution of methyl starch was equal to 0.43）at reactants ratio of m（Starch）∶m（NaCl）∶m[（CH3O）2CO] = 10∶4∶125 within 13 minutes microwave irradiation.Reaction extent was increased,reaction time was reduced significantly,but thermal stability of methyl starch decreased obviously compared with native starch.