Forming Structure in Porous Polyvinylformal Filters for Selective Water Sorption

The data on generating porous structure from PVF during PVA acetalization is presented. The main parameters comprising the average pore diameter, the ratio of open to closed pores, the apparent density, porosity, and water absorption are estimated. It is shown that the density of PVF samples is about 0.54‒0.58 kg/cm³, and the total porosity is 55–57%. The number of open pores decreases from 38% to 23% when the mixing speed grows from 800 to 1200 rpm. The time dependences of PVF water absorption are obtained and it is established that water is mainly sorbed by open pores, reaching the value of 417%.