精制棉成熟度及硝化工艺对高氮量NC硝化均匀性的影响

为研究精制棉质量、硝化工艺对高氮量硝化纤维素(NC)硝化均匀性的影响规律,采用H_2SO_4-HNO_3-H_2O体系对不同成熟度的精制棉进行硝化处理,通过改变硫酸-硝酸比、硝化时间制备了高氮量NC,利用偏光显微镜测试NC的含氮量及硝化均匀性,探讨了不同成熟度和硝化工艺对高氮量NC的氮量及硝化均匀性影响规律,同时将不同均匀性的NC经胶化压制成典型的发射药,对比了相应药粒侧断面的微观形貌。结果表明,精制棉成熟度高时,制备的高氮量NC均匀性优于成熟度低的产品;硫硝比为2.7时,制备的NC含氮量高、硝化均匀性较好;以成熟度大于70%的精制棉为原料,制备NC的硝化均匀性指标-均方差约2.3;30~35min硝化效果最佳,延长硝化时间对氮量影响不大,均匀性反而降低。表明,以成熟度高的精制棉为原料,通过控制硝化体系中硫硝比和硝化时间,可得到均匀性较好的NC,用其压制单基发射药的胶化和压伸成型质量可得到明显改善。

Effect of Maturity and Nitrification Process of Purified Cotton on the Nitrification Uniformity of Nitrocellulose with High-nitrogen Content

To study the influence law of purified cotton quality and nitrification process on the nitrification uniformity of nitrocellulose (NC) with high-nitrogen content, purified cottons with different maturity were nitrified via H₂SO₄-HNO₃-H₂O system, and NC with high-nitrogen content was prepared by changing sulfuric acid-nitric acid ratio and nitrification time. The nitrogen content and nitrification uniformity of NC were measured by polarizing microscope. The influence law of different maturity and nitrification processes on the nitrogen content and nitrification uniformity of NC with high-nitrogen content was discussed. At the same time, typical gun propellants were suppressed via. gelatinization of NC with different uniformity, and the microstructure of the lateral cross sections of the corresponding granules was compared. Results show that the nitrification uniformity of NC prepared from purified cottons with high maturity is better than that of low maturity products. NC prepared by low sulfuric acid-nitric acid ratio as 2.7 has higher nitrogen content and better nitrification uniformity. Using purified cotton of maturity as more than 70% as raw material, the nitrification uniformity index-variance of prepared NC is about 2.3. When nitrification time is about 30 mins, the nitrification effect is the best, the prolongation of nitrification time only has a little effect on the nitrogen content, but the uniformity decreases. So through the control of sulfuric acid- nitric acid ratio in the nitrification system and nitrification time, using purified cotton of high maturity as raw material, the NC with better uniformity can be obtained and the gelatinized extrusion molding quality of high-uniformity NC-pressed single-base propellant is significantly improved.