Printed in U.S.A. Form No. 51-965A-97

Historically tape properties such as peel adhesion, shear and tack have been used to characterize the perfor-mance of pressure sensitive adhesives targeted for transdermal applications; however, variability from the test methods often resulted in wide specification limits and poor correlation of test data with adhesive performance. In addition, although these tests could qualitatively predict how quickly a system would bond to the skin, how easily the system would resist cold flow and how much force would be required to remove the system from the skin, these tests did not accurately measure how well the systems would wear. In order to better understand and predict the wear performance of transdermal systems, an understanding of the viscoelastic response of the bulk adhesive, the surface energies of both the adhesive and the adherend and the influence of the backing substrate must be developed. Within the last couple of decades, rheology has emerged as a new and innovative technique for not only charac-terizing viscoelastic properties of polymers, but for also predicting wear performance properties of pressure sensitive adhesives (1-5) and as shown below, attempts have been made to correlate traditional tape properties with rheological responses: In the early 1980’s, Dow Corning personnel began investigating different rheological tools for characterizing silicone adhesive performance. Data have shown that for viscoelastic material, such as silicone pressure sensitiv