MISCIBILITY AND SHEAR CREEP RESISTANCE OF ACRYLIC PRESSURE-SENSITIVE ADHESIVES - ACRYLIC COPOLYMER AND TACKIFIER RESIN SYSTEMS

The miscibility between an acrylic copolymer and a tackifier resin was investigated in terms of phase diagrams, glass transition temperature s (T-g's), and dynamic mechanical properties of blends, Shear creep re sistance (holding power, t(b)) of the blends was measured as a functio n of both temperature and stress (sigma(0)) in order to obtain the mas ter curves. It was found that the shear creep resistance of the pressu re-sensitive adhesives (PSAs) was closely related to the miscibility b etween the components and viscoelastic properties of the blends. The m aster curve of the miscible blends shifts toward a longer time scale a s the amount of tackifier resin in the blend is increased as a result of the modification of the bulk properties, and their behavior greatly depends on the glass transition temperature (T-g) and storage modulus (G') of the blends. However, the master curve of immiscible blends wh ere two phases exist in the system does not shift greatly toward a lon ger time scale, because T-g and the storage modulus of the blend do no t change greatly. (C) 1995 John Wiley & Sons, Inc.