机械活化木薯淀粉羧甲基化产物的结构表征

采用搅拌球磨机对木薯淀粉进行机械活化，以活化60min 的木薯淀粉为原料，氢氧化钠为催化剂，一氯乙酸为醚化剂干法合成羧甲基淀粉，利用红外光谱、扫描电子显微镜、X 射线衍射等手段对产物的结构进行表征分析，并与原木薯淀粉合成的羧甲基淀粉进行比较。结果表明：机械活化对木薯羧甲基淀粉的结构有显著影响；原木薯淀粉的羧甲基化反应受表面控制，主要发生在无定形区，部分发生在结晶区，产物含有结晶结构并保留着淀粉的颗粒形态；活化淀粉的羧甲基化反应在淀粉团粒表面及内部均匀进行，产物呈无规则黏连形态，是无定形的聚集状态结构。

Structural Characterization of Carboxymethylated Cassava Starch Prepared Based on Mechanical Activation

Cassava starch was mechanically activated for 60 min using a stirring type ball mill in order to provide activated cassava starch for preparing carboxymethylated starch using NaOH as a catalyst and ClCH2COOH as an etherification agent. The structure of carboxymethylated cassava starch was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). After mechanical activation, the structure of cassava starch had no obvious changes. Carboxymethylation reaction could be observed on the surface and interior of activated cassava starch. Its carboxymethylated counterpart showed an irregular adhesive form and an aggregative state and maintained both the precarboxymethylation crystal structure and morphological features of starch granules. In contrast, carboxymethylation controlled on the surface area was mainly completed in the amorphous zone and partly in the crystalline area of inactivated cassava starch.