中文摘要：

在低pH值条件下采用NaIO4氧化羧甲基纤维素（CMC）,制备了二醛羧甲基纤维素（DACMC）,通过FT-IR、^13C NMR、XRD和AFM等研究了pH值对NaIO4氧化CMC程度的影响,以及pH值对DACMC结晶结构、形貌结构、热稳定性的影响.结果表明：pH值对NaIO4氧化CMC的程度有显著的影响,但缺乏规律性,当pH值为1.5时其氧化程度最高（醛基含量最大为54.35%）;FT-IR和^13C NMR结果证实了在CMC分子链上有羰基产生;DACMC的结晶度均大于CMC,且随反应体系pH值的增加而增大;由于失水葡萄糖环的断裂,DACMC的分子链更加柔软,相互缠结得更加紧凑、规整,表面Z向尺寸随着醛基含量的增大而降低;DACMC的热稳定性差于CMC,pH=1.5的条件下制备的DACMC的热稳定性最差.

英文摘要：

Dialdehyde carboxymethyl cellulose（DACMC） was synthesized by oxidizing carboxymethyl cellulose（CMC） with periodate NaIO4 at low pH value,and the effects of pH value on the oxidation degree of CMC,as well as on the crystal structure,morphology and thermal stability of DACMC,were investigated by means of FT-IR,^13C NMR,XRD and AFM.The results show that（1） pH value significantly and irregularly affects the oxidation degree of DACMC,and the oxidation degree reaches its maximum at pH 1.5,with an aldehyde content of 54.35%;（2） carbonyl groups are introduced into the molecular chain of CMC,which is verified by FT-IR and 13C NMR results;（3） the crystallinity of DACMC is higher than that of CMC and increases with pH value;（4） due to the break of glucopyranose rings,the molecular chain of DACMC becomes softer,entangles with each other more compactly and arranges more regularly,while the Z dimension of DACMC surface decreases with the increase of aldehyde content;and（5） the thermal stability of DACMC is poorer than that of CMC,especially in the condition of pH 1.5.