Authors: R. Shanks
Affilation: RMIT University, Australia
Pages: 600 - 603
Keywords: nano-silica, adhesion, cohesion, viscoelastic, network
The aim of this research is to increase cohesion of a PSA by including silica nanoparticles. The silica nanoparticles form reversible agglomerates and bind polymer molecules by adsorption. The adhesive becomes a reversible gel. Under pressure over a time suitable for bond formation the PSA can still flow due the time scale for the reversible silica physical gel to respond. The effect of cohesion on PSA bond formation can be characterised using modulated force thermomechanical analysis. The change in relaxation of a nano-silica filler on an elastomer, analogous to a PSA, has been measured using stress relaxation. The mastercurve measurements on bond strength (peel test) and viscoelastic cohesion (modulated force thermomechanical analysis) demonstrates the contribution of a bulk property (cohesion) to a surface property (bond strength) and reveals the mechanism of PSA. The PSA mechanism leads to the concept that an adhesive bond can be enhanced through formation of physical crosslinks by the high surface to volume ratio of a nanofiller. PSA–silica nanocomposites enable better control of adhesive bond formation and subsequent removal than adventitious chemical gelation during polymerization.