Development of an acoustic technique for assessing structure-property characteristics of polymeric thin films using high pressure

Cellulose acetate membranes are used in a wide range of commercial separation processes. A significant concern in the manufacture of these membranes is the development of large-scale defects termed macrovoids (MVs). Also, one impediment to the design of membranes with improved separation properties is the lack information regarding structural changes and response when the membranes are subjected to high pressures (4-6 MPa) typical of desalination applications. Acoustic time-domain reflectometry (ATDR) has been developed and implemented to give real-time membrane data during separation processes. The ATDR data provides thickness measurement and a “signature” which can be related to membrane morphology. The data for the membranes are compared using optical reflectometry and Sem analysis to provide the microstructure and MV characteristics. Compaction data has been obtained using ATDR to give an insight into membrane performance. Use of ATDR to discern structural defects and measure compaction in polymeric membranes has not been reported previously in the literature