Determination of the effective degree of cross-linking of porous cellulose membranes cross-linked with bifunctional epoxides

The cross-linking efficiency of a continuous process for the production of porous cellulose membranes cross-linked with 1,4-butanediol diglycidyl ether (BDDE) under variation of four different process parameters (concentration of cross-linker, catalyst concentration, reaction temperature and reaction time) was studied. The analysis of the resulting network properties is based on gravimetric and titrimetric methods complemented by one-dimensional H-1 NMR analysis after degradation of the cross-linked cellulose membranes in aqueous zinc chloride solution. NMR results indicate that around 50 % of BDDE molecules are effectively cross-linking, the number being almost independent of the cross-linking conditions. Furthermore, thermogravimetric analysis of the cross-linked membranes showed a direct correlation between the degree of cross-linking and the decomposition temperature of the cellulose membranes.