TEMPO/NaBr/NaClO体系下氧化淀粉的制备及其结构性能表征

以玉米淀粉为原料,以2,2,6,6-四甲基-1-哌啶氧基自由基(TEMPO)和NaBr为催化剂,NaClO为氧化剂,制备了氧化淀粉,研究氧化剂用量、氧化介质的pH、反应温度及反应时间等对氧化淀粉羧基含量和得率的影响。确定了玉米淀粉适宜的氧化条件为:NaClO质量分数为35%(以淀粉质量为基准),氧化介质的pH为10.5,反应温度0℃,反应时间2.5 h,此条件下氧化淀粉的羧基质量分数为5.30%,得率为88.8%。通过红外光谱(IR)和扫描电镜(SEM)对氧化淀粉的结构进行了表征,探讨了氧化淀粉的应用性能,氧化淀粉的糊液黏度由100 mPa.s下降至3.0 mPa.s,透光率由47.86%增加到94.19%。

Preparation and structure characterization of oxidized starch in TEMPO/NaBr/NaClO oxidation system

Oxidized starch was prepared using corn starch as the raw material and NaClO as the oxidant catalyzed with a complex catalyst 2,2,6,6-tetramethyl-piperidine-1-oxyl(TEMPO) and NaBr.Effects of the amount of NaClO,pH of reaction media,reaction temperature and reaction time on the yield and carboxyl group content of oxidized starch were investigated.The suitable oxidation conditions were determined as follows: the amounts of NaClO was 35 %(based on the weight of corn starch) respectively,pH of reaction media was 10.5,reaction temperature was 0 ℃,reaction time was 2.5 h.The content of carboxyl group of the oxidized starch obtained on the aforesaid conditions reached 5.30 %,and the yield of oxidized starch was 88.8 %.Furthermore,the structure and the application properties of oxidized corn-starch were characterized by IR and SEM.Comparing to raw starch,the paste viscosity of the oxidized starch decreased from 100 mPa·s to 3.0 mPa·s,and transmittance of paste liquid increased from 47.86 % to 94.19 %.