The Study Of Esterification Reaction And Stability Treatment Of NC

Objective: Esterification reaction and stability treatment of NC was studied from theoretical and actual production aspects. This paper describes the principle of NC estering process and stability treatment process and analyzes factors affecting NC estering quality and stability. Nitration degree, key index for NC quality controlling, is thoroughly studied and an expert control system for NC stability treatment process is constructed.Means:Property of cellulose, content of acid mixture, temperature and time of esterification are main factors which have affection on nitrogen content of NC. Cellulose is to be subject to pre-treatment before esterification is given. NC made by cellulose being treated by flash treatment modification contains higher nitrogen than cellulose without modification treatment and uniformity of distribution of nitric ether base is greatly improved also. When sulfuric acid increased in sulfuric acid and nitric acid mixture, esterification reaction will be slower, water increased in acid mixture and nitrogen content of NC appears reducing tendency. While esterification may be speeded up by rising temperature, but esterification reaction is of reversible reaction, by-products will be increased and viscosity as well as polymerization and stability of NC will be decreased. It takes long time to make esterification reaction to be in balance, with esterification time increased, oxidation and hydrolysis and etc. side reaction will destroy NC, nitrogen content and viscosity will decreased along with.Stability treatment process is mainly decided by diffusion speed of free sulfuric acid. Stability treatment period can be decreased by temperature rising, pressure increasing and improving cellulose's structure to be more loose. To accurately control boiling temperature by expert intelligent method and control boiling pressure by real time system and expert system together can provide an effective control for NC stability treatment process and shorten stability treatment period, to optimize process operation conditions, improve process control level, especially safety in production process has been solved, and product quality and uniformity has been obviously improved.conclusion: Property of cellulose, content of acid mixture, temperature and time of esterification are main factors which have affection on nitrogen content of NC.In Stability treatment process, To accurately control boiling temperature by expert intelligent method can shorten stability treatment period, to optimize process operation conditions, improve process control level, especially safety in production process has been solved, and product quality and uniformity has been obviously improved.