Contact time and interfacial fracture energy of tacky polymers

The spontaneous adhesion of tacky polymers to rigid materials as a function of contact time at constant temperature and applied pressure is considered. Polymer-substrate attachment, assumed to initiate as microscopic nuclei that form at random locations on the substrate and expand to cover their surroundings, is studied from a probabilistic perspective. Calculation yields a description of the natural law governing the increase in the interfacial fracture energy of tacky polymers on rigid substrates with contact time. The description assigns to each polymer-substrate pair three parameters that characterize the pair's bonding behavior and serve as a signature for the pair. The proposed description of the underlying natural law is verified with published experimental data. Its main features and implications are examined. The findings pertain to pressure sensitive adhesion and tack, and are used to interpret experimental results. The scheme not only accounts for the reported results of 14 polymer-substrate pairs but also depicts other distinct bonding behaviors yet to be observed. (C) 2004 Wiley Periodicals, Inc.