Compositional Effects on the Adhesion of Acrylic Pressure Sensitive Adhesives

The contact mechanics-based Johnson−Kendall−Roberts technique has been used to study the adhesion of cross-linked 2-ethylhexyl acrylate- co -acrylic acid (2EHA- co -AA) elastomers as models of pressure sensitive adhesives (m-PSA). We have addressed the effect of m-PSA composition on intrinsic solid surface energetics and on the mechanical performance of m-PSA. The measured surface energies of the m-PSA were all approximately 30 mJ m - 2, indicating surfaces dominated by methylene groups. The extent of adhesion hysteresis for the m-PSA used in our measurements was not a strong function of acrylic acid content implying that the main mechanism contributing to the adhesion of practical un-cross-linked or lightly cross-linked PSA is the viscoelastic dissipation. Several technical and physical issues concerning contact mechanical measurement of adhesion and the observed rate-dependent patterns of adhesion have been addressed.