N-乙酰化壳聚糖的FTIR和XRD研究

Study on N-Acetylated Chitosans by FTIR and XRD

壳聚糖分子的脱乙酰度(DD)是影响壳聚糖性质的主要因素之一。文章通过壳聚糖的N-乙酰化反应制备了不同脱乙酰度的壳聚糖。采用傅里叶变换红外光谱(FTIR)和X射线衍射(XRD)分别研究了由N-乙酰化反应得到的不同脱乙酰度的壳聚糖的红外光谱特性和晶体结构,并由此分别计算确定了样品的脱乙酰度和结晶度,探讨了N-乙酰化程度对壳聚糖脱乙酰度以及结晶度的影响。由FTIR可知,随N-乙酰程度的增加,壳聚糖分子中剩余氨基的反应速度变慢。另外XRD也表明,伴随N-乙酰反应,壳聚糖分子的结晶区被破坏,规整度下降,并逐渐形成新的结晶区。

The degree of N-deacetylation （DD） is an important property of chitosan. In the present article the reaction of N-aeetylation was applied to prepare six ehitosan samples with various DDs. The samples were studied by FTIR and XRD to investigate their IR absorbanee eharaeteristies and erystallinity, from whieh the DDs and erystallinity index （CrI） of ehitosans were also determined respectively. The influence of N-aeetylation on DD and CrI was also diseussed, and it could be found from FTIR that the N-aeetylation reaetion became difficult for the remaining amino group in ehitosan molecule as the reaetion procee- ded. XRD also indieated that the erystalline zone was broken by N-aeetylation gradually, and another kind of erystal form appeared instead.