摘要:
In this paper, the response surface method was used to optimize the preparation process of dialdehyde starch by one-step acidolysis oxidation.Then corn starch as raw material, hydrochloric acid (HCl) as acid solution and sodium periodate (NaI O4) as oxidant. The concentration of HCl, the concentration of starch milk, the reaction temperature and the reaction time were the variables. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis proved that the dialdehyde starch was successfully prepared. The gelatinization properties, particle morphology, crystalline structure and thermal properties of dialdehyde starch were characterized by rotating viscometer, scanning electron microscope (SEM) , X-ray diffractometer (XRD) and thermogravimetric analyzer (TGA) . The results showed that the influence of the aldehyde group content was reaction temperature> reaction time> starch milk concentration> HCl concentration. The optimum preparation process was as follows: the HCl concentration was 1. 2 mol/L, the concentration of starch milk was 7%, the reaction temperature was 49 °C, and the reaction time was 4 h. At this moment, the aldehyde group content was 85. 17%, close to the theoretical value maximum of 86. 26%, showing the optimized result believable. After acid oxidation, the gelatinization viscosity of dialdehyde starch was reduced to 30 mP a·s, and the reaction activity and maneuverability were significantly improved. SEM analysis showed that the dialdehyde starch granules were depressed in the middle, and showed a ring structure. XRD analysis showed that the crystalline structure of the starch was destroyed, and the recrystallization increased the crystallinity to 36. 05%. TGA analysis showed that the initial temperature of thermal decomposition of dialdehyde starch was decreased, but the residual ratio of decomposition was increased, indicating that the thermal plasticity and thermal stability increased.%本工作采用响应曲面法优化了一步酸解氧化制备双醛淀粉的工艺, 以玉米淀粉为原料、盐酸 (HCl) 为酸解剂、高碘酸钠 (NaIO4) 为氧化剂, 设置HCl浓度、淀粉乳浓度、反应温度和反应时间为变量.傅里叶变换红外光谱 (FT-IR) 和X射线光电子能谱 (XPS) 分析证明本实验成功制得了双醛淀粉.采用旋转黏度计、扫描电子显微镜 (SEM) 、X射线衍射仪 (XRD) 和热重分析仪 (TGA) 对双醛淀粉的糊化性能、颗粒形貌、结晶结构和热性能进行了表征.结果表明, 对醛基含量的影响大小依次为反应温度>反应时间>淀粉乳浓度> HCl浓度.最佳制备工艺为:HCl浓度为1. 2mol/L, 淀粉乳浓度为7%, 反应温度为49°C, 反应时间为4 h.在该条件下制得的双醛淀粉的醛基含量为85. 17%, 与理论最大值86. 26%接近, 说明优化结果可信.酸解氧化后, 双醛淀粉的糊化黏度降至30 mPa·s, 可显著提高反应活性和可操作性.SEM分析显示, 双醛淀粉颗粒中间凹陷, 呈现出环状结构.XRD分析表明, 淀粉的结晶结构发生破坏, 重结晶使结晶度增大至36. 05%.TGA分析表明, 双醛淀粉受热分解起始温度降低, 但分解残余率提高, 说明其热塑性和热稳定性有所提高.