硝化体系及温度对硝化棉含氮量均匀性的影响

Effect of Nitration System and Temperature on Nitration Uniformity of Nitrocellulose Fibers

以精制棉为原料,采用HNO3/H2SO4/H2O和HNO3/CH2Cl2两种硝化剂体系制备硝化纤维素,通过偏光显微镜分析测试了硝化产品的氮量及氮量分布(硝化均匀性),系统研究了硝化体系组成及硝化温度对硝化棉氮量及均匀性影响规律。研究结果表明:HNO3/H2SO4/H2O体系中水含量的增加会显著降低硝化棉产物含氮量,但适当增加水含量有利于得到氮量分布更为均匀的硝化棉;硫酸含量高的体系,制得的硝化棉氮量高,但硝化的均匀性变差;硝化棉含氮量均匀性随HNO3/CH2Cl2中HNO3含量增加先升高、后下降直至保持不变;增加硝化温度,有利于酯化试剂扩散,硝化棉含氮量分布均匀性有所增强。

The nitrocellulose is synthesized by nitrating the cotton linter with HNO3/ H2SO4/ H2 O or HNO3/ CH2Cl2 as nitration agent. The nitrogen content and its distribution（ uniformity of nitration） of nitrocellulose are analyzed by a polarizing microscope. The influences of the components of nitration system and nitrification temperature on the nitrogen content and uniformity of nitrocellulose are studied. The nitrogen content of nitrocellulose obviously decreases with the increase in water content in HNO3/ H2SO4/H2 O. The uniformity of nitrocellulose would be improved if the water content increases appropriately.Mixed acids with high sulphuric acid content is employed to give a material of high nitrogen content but bad uniformity. With the increase in HNO3 content in HNO3/ CH2Cl2,the uniformity of nitrocellulose is improved firstly,and then is declined before unchanging. The uniformity of nitrocellulose is improved with the increase in nitration temperature which is conducive to the diffusion of esterification reagents.