ABSTRACT
Properties related to flow are the lack of crystallinity, the lack of orientation, the need for cold flow, the high rate of relaxation, and the ductility. It should be pointed out that in comparison to the flow of plastics or rubber during processing, the flow of pressure-sensitive adhesives (PSAs) occurs isothermally. The role of the relaxation phenomena and their influence on the mechanical properties of plastics is well known. The dependence of the mechanical properties of plastic blends on the relaxation ability was demonstrated. A more thorough examination of the main rheological and mechanical characteristics of plastics/elastomers and PSAs reveals a lot of differences in their properties. The functional groups in classical adhesives serve mainly as crosslinking sites, while in PSAs are adhesion promoters. Thus in hot-seal adhesives the resin improves the adhesion to difficult substrates, decreases the blocking resistance, and lowers the seal temperature.
