Physicochemical characteristics of porous crystalline cellulose and formation of an amorphous state of ethenzamide by mixing

Abstract

The physicochemical characteristics of porous crystalline cellulose (PCC) have been investigated. The specific surface area and pore size distribution curve of PCC were determined from nitrogen gas adsorption isotherms. The specific surface area and pore volume of PCC were decreased on grinding with a mortar and pestle or after storage at high relative humidities, which was attributed to the destruction of the porous structure of PCC. When a physical mixture of ethenzamide (EZ) and PCC was stored for 1 month under dry conditions, amorphization of EZ was observed. After heating the mixture of PCC and EZ at 100°C for 2 h, crystalline EZ changed to an amorphous state. In the stored or heated mixtures of PCC-EZ, EZ molecules would be adsorbed physically onto the pore surface of PCC. The heated mixture of PCC-EZ showed a high rate of dissolution of EZ in polar and nonpolar solvents. Nonporous microcrystalline cellulose was unable to transform crystalline EZ to the amorphous state.