有机溶剂体系中羟烷基纤维素的硝化

Nitrification of Hydroxyalkyl Cellulose in Organic Solvent

选用HNO3/CH2Cl2有机硝化体系研究羟烷基纤维素的酯化过程。用XRD技术和jade5.0分析软件测试分析羟乙基纤维素(HEC)和二羟丙基纤维素(DHPC)的结晶情况,用显微镜观察酯化中形成凝胶的颗粒状态。研究表明,HEC和DHPC的酯化分为两个阶段,在达到凝胶临界点之前的酯化与纤维素类似,在达到凝胶临界点时,含氮量最高,形成凝胶之后,含氮量迅速降低。摩尔取代度(MS)越大,含氮量越低,并且MS大的硝化基体在硝化过程中更易形成凝胶。同等MS的HEC、DHPC,HEC结晶度小,在硝化过程中易形成凝胶。

Two kinds of hydroxyalkyl cellulose,hydroxyethyl cellulose（HEC） and dihydroxypropyl cellulose（DHPC） were nitrified in HNO3/CH2Cl2 system.The esterfication processes of HEC and DHPC in HNO3/CH2Cl2 system were studied.Crystallization properties of NHEC and NDHPC were analyzed by XRD and Jade5.0 analysis software.The morphology of gel particles formed in the nitrification were observed by microscope.The results show that the nitrification process of HEC and DHPC is proved to contain two stages divided by the separation-gel transition point,The first nitrification stage（before gel forming） is similar to cellulose,the nitro content reach its maxmium when the gel begin forming and declined rapidly as gel continued forming in the second stage.The larger the molar substitution（MS） is,the lower the nitro content is,and the easier the gel forming.HEC was easier to form gel in the nitrification process than DHPC with the same MS of hydroxyalkyl cellulos due to its lower degree of crystallization.