片工艺法制备羧甲基瓜尔胶的取代均匀性

Substitution Uniformity of Carboxymethyl Guar Synthesized by Split Process

陈卫平 叶应庆 季美芳 何建平

CHEN Weiping，YE Yingqing，JI Meifang，HE Jianping

为研究用片工艺法改性羧甲基瓜尔胶的取代均匀性，采用环境扫描电镜能谱法（ESEM-EDS）分析了片工艺法合成羧甲基瓜尔胶片的内部截面元素分布，用核磁共振氢谱法（1H-NMR）分析了胶片不同片层的取代度。结果表明，碱化剂NaOH在瓜尔胶片内部均匀扩散，NaOH浓度对扩散均匀性基本无影响；醚化剂氯乙酸钠分子体积较大，无法快速有效地在瓜尔胶片内扩散均匀，胶片内部的氯乙酸钠含量低于胶片外部；采用片工艺法合成的羧甲基瓜尔胶片的取代度由外及里依次降低，从0.291降至0.197，外层取代度是内层的1.48倍。由片工艺法制得的羧甲基瓜尔胶是非均匀取代的改性瓜尔胶产品。图7参14

In order to study the substitution uniformity of carboxymethyl guar produced by split process，the internal cross-section element distribution of carboxymethyl guar split was analyzed by environmental scanning electron microscopy spectroscopy（ESEM-EDS），and the degrees of substitutions（DS）of different layers of carboxymethyl guar split were determined by 1H-NMR.The results showed that alkalizer NaOH diffused uniformly through the guar split，and the concentration of NaOH had no effect on its diffusion behavior. The etherifying agent sodium chloroacetate was unable to diffuse uniformly due to a large molecular. The content of sodium chloroacetate inside the split was lower than that of outside the split. The DS of the carboxymethyl guar split decreased from 0.291 for the outer layer to 0.197 for the inner layer，which revealed that the split process gave a heterogeneous product.

10.19346/j.cnki.1000-4092.2019.04.006