Europhys. Lett., 66 (4) , pp. 513-519 (2004)
DOI: 10.1209/epl/i2003-10231-y

Tackiness of pressure-sensitive adhesives: An ultra-small-angle X-ray scattering investigation

P. Müller-Buschbaum, T. Ittner and W. Petry

Technische Universität München, Physik-Department E13 James-Franck-Strasse 1, D-85747 Garching, Germany

(Received 9 December 2003; accepted in final form 5 March 2004)

Abstract
The debonding of a model pressure-sensitive adhesive (PSA) poly- n-buthylacrylate is investigated by a combination of the mechanical tack test, optical microscopy and in situ ultra-small-angle X-ray scattering. From the mechanical test, macroscopic values such as force-distance curves are determined. The force-distance curve exhibits the typical non-linear behavior. With microscopy the macroscopic cavitation structure is observed. Scattering addresses the structure of the PSA on a microscopic level for the first time. As a new feature, a sub-structure of the usual optically resolvable macroscopic fibrils between the PSA surface and the probe punch is detected. The sub-structure exists over a large distance between the PSA and the probe surface and remains constant in diameter. This behavior of the sub-structure as well as the dependence of the force plateau on the film thickness are compared with theoretical predictions.

PACS
61.10.Eq - X-ray scattering (including small-angle scattering).
81.70.Bt - Mechanical testing, impact tests, static and dynamic loads.
68.35.Np - Adhesion.

© EDP Sciences 2004