Effect of swelling pretreatment to cotton linter on nitrogen content and its distribution uniformity of nitrocellulose

A testing instrument developed by Beijing Institute of Technology has been used to perform the research of this work, which could test the nitrogen content and its distribution uniformity of nitrocellulose (NC). The effects of swelling time and temperature, concentration of swelling agent and the kind of swelling agents on the swelling results of the cotton linter, nitrogen content and its distribution uniformity of NC were investigated. The testing results show that: the optimal swelling time is 1.0 hour and the optimal concentration of swelling agent is 8%; the swelling ability of swelling agents follow a descending trend in a sequence of potassium nitrate, urea, sodium acetate, sodium salicylate and thiourea=hydroxyphenol; and low temperature is benefit to the swelling effect. The higher the swelling degree of the cotton linter, the narrower the nitrogen distribution is.