Investigations of the time dependence of the conversion of cellulose to alkali cellulose by X-ray diffraction

The course of the lattice transition of cellulose by interaction with aqueo us and aqueous-ethanolic solutions of NaOH was studied using two methods. F irst, the conversion reaction was stopped by adding acetic acid and subsequ ent determination of the amount ol cellulose II by a conventional WAXS tech nique. Second, the change oi the crystalline lattice was recorded in situ b y a series of WAXS-patterns obtained by synchrotron radiation with a time r esolution of 15 s. With an aqueous lye oi 12 to 18% NaOH concentration, the lattice transition is completed in less than 15 s. An increasing part of e thanol in the reaction system, however, reduces the rate of transition dras tically Lattice transition due to alkalization was approached kinetically b y a second order law, rate constants for aqueous NaOH solutions were obtain ed by extrapolation. Causes for the different behaviour of water and ethano l are discussed.