Effect of nitrification system and refined cotton drying process on the nitrogen distribution uniformity of nitrocellulose

Polarizing microscope has been used to investigate the nitrogen distribution uniformity of nitrocellulose (NC) prepared from cotton linters which are refined by different pretreatment methods, and one of nitrating system is ordinary mixtures of nitric and sulfuric acids and water while the other one is green sulfur-free nitrating system - HNO₃/CH₂Cl₂. The results show that the uniformity of the product of nitrification will change obviously as the treatment of raw cotton cellulose changing, the performance of NC has a more obvious change if the raw cotton cellulose containing water be dried, because of the role of keratinization during the drying process of the cotton cellulose. The role of the keratinization makes the nitrogen content and nitrogen distribution uniformity of NC worse than that NC prepared from cotton linters without being dried. The homogeneity of nitrocellulose changes regularly at different nitrogen content levels, NC with mid-nitrogen content, such as 12%, has a better uniformity than those with 13% or 11%.