Chemical physics of cellulose nitration

Resumo

The physical mechanisms responsible for the kinetics of nitration of cellulose raw materials of different origin have been studied. It has been shown that the main nitration rate-limiting factor is the speed of untwisting of supercoiled cellulose fibers. This process limits the penetration of nitrating agents into microcrystalline regions and, thus, the total reaction rate. The constructed physical model provides an adequate explanation of all the experimentally observed features of the cellulose nitration process, particularly as a function of cellulose origin (cotton, flax, wood) and preparation/treatment methods (sulfite, sulfate, bleached, refined with sulfurous or boric acids or acetone). The theoretical results have been tested in practice.