CHARACTERISTICS OF WATER-ADSORPTION ISOTHERMS FOR MATERIALS CONTAINEDIN A BOX OF A TOBACCO PRODUCT

An experimental study has been carried out on the characteristics of w ater adsorption isotherms for typical materials used in a box of tobac co products or cigarettes. Equilibrium moisture contents for different varieties of tobacco, papers, filters and activated carbons were meas ured with a flow-type adsorption system under the conditions of a cons tant temperature at 303 K and relative humidities ranging from 5 % to 80 %. A modified Dubinin-Astakhov equation was accurately applied to r epresent the water adsorption isotherms for all materials, These isoth erms were characterized by three parameters contained in the equation and divided into three groups; i.e. 1)tobacco, 2)papers as well as fil ters, and 3)activated carbons, depending mainly on pore sizes as well as the degree of swelling of the materials used. Under a relative humi dity of around 60 %, the main water migration was found to take place in the tobacco and the percentage of migrated water to the total was a ssessed to be more than 80 %. The results' suggested that the selectio n of film, which has a function of being a high vapor barrier, is impo rtant to maintain the constant moisture content of tobacco during stor age and marketing.