Effect of nitration system and temperature on nitration uniformity of nitrocellulose fibers

The nitrocellulose is synthesized by nitrating the cotton linter with HNO₃/H₂SO₄/H₂O 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/H₂O. 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.