Spectrophotometric determination of water vapor permeation through polymer films

Abstract

SynopsisA novel method for measuring the permeation of water vapor through polymer films is described. A cellulose detector film incorporating cobalt chloride in a blue anhydrous form is sealed between two pieces of test film in a specially designed cell. The cell is placed in a controlled temperature and humidity cabinet, and the disappearance of the blue color of the cobalt chloride is recorded spectrophotometrically as water vapor diffuses through the test film into the detector film. This simple method of determining water-vapor-transmission rates is more rapid than standard gravimetric procedures because of the highly sensitive detection technique.