The effect of tackifiers on the viscoelastic properties of polyolefin based pressure sensitive adhesives

The effects of nonpolar tackifiers on the glass transition temperature, terminal relaxation time, plateau modulus and steady shear viscosity of polyolefin-based Pressure Sensitive Adhesives (PSAs) were investigated. Free volume theory and Gordon-Taylor equation are used to explain the special effects of tackifiers on the glass transition temperature (related to the segmental relaxations) of the PSA systems. The Plateau Modulus and Monomeric Friction Coefficient are related to entanglements and zero shear viscosity of the systems respectively. The terminal relaxation time (related to the whole molecular chain relaxations) was calculated from the plateau modulus and zero shear viscosity. Explanations were offered as to why tackifiers appear to have the "paradoxical" effect of increasing the glass transition temperature but decreasing the plateau modulus of the base polymer.; This research was initiated to investigate the formulation of adhesives for bonding to low surface energy polymers. Specifically, resin-coated (RC) photographic prints are used by fine art photographers. These are photographic papers that are coated with polyethylene and designed to be unaffected by excessive humidity. In addition, it was necessary to limit this research to adhesives that are reversible on demand (i.e. thermoplastic systems) since irreversible adhesives would permanently alter the photograph.; In order to develop appropriate adhesives applicable to resin coated papers, the surface energy of the PSAs and substrate, the results of preliminary testing of shear and peel strength and UV aging were considered and discussed. Polyolefin based PSAs (tackified by Regalite resin R1100) show appropriate peel, shear strength and good UV light stability which enable them to mount the resin coated papers and to be removed cleanly from the surface of the substrate later.