Determining Sorption Rate by a Continuous Gravimetric Method

Abstract : A rate-determining step in the decontamination of chemical agent resistant coating (CARC) is thought to be the rate of solvent sorption into the pores of the paint. Because of systematic errors inherent in the conventional "blotting" method, a continuous gravimetric method was developed to determine the initial sorption rates of various solvents into MIL-C-53039A CARC and total amounts of solvent sorbed (t=30 min). Using an HP Vector VL computer interfaced with a Mettler AX205 Delta Range balance, mass and time were automatically recorded in an Excel file while CARC coupons were submerged in solvent. Initial sorption rates were determined for butyl acetate, butyl ether, cyclohexane and propylene carbonate. A comparison between total sorption values (t=30 min) from the continuous gravimetric method and values from the "blotting" method (ASTM D543) shows a statistical difference between the two methods for CARC coupons.