TEXTURE CONTROL OF FREEZE-DRIED RESORCINOL-FORMALDEHYDE GELS

Resorcinol-formaldehyde gels synthesized in water were freeze-dried to a monolithic and highly porous material. The influence of dilution an d aging time on the porous texture after drying were studied using nit rogen adsorption-desorption, mercury porosimetry and small angle X-ray scattering. The drying method produces very large pores by ice crysta l growth, and changes the porous texture of the original wet gel. Free ze-drying does not substantially modify microporosity and mesoporosity , which are mainly fixed by reactant concentration and aging time. (C) 1998 Elsevier Science B.V. All rights reserved.