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

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 forcedistance 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.

Near-Surface Composition Profiles and the Adhesive Properties of Statistical Copolymer Films Being Model Systems of Pressure Sensitive Adhesive Films

“…By applying a slight pressure, a releasable bond to the substrate is formed (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). In many PSA applications, a controlled release of the adhesive bond is desired, making use of the ability to undergo several cycles of bonding and detaching.…”

Microscopic structure in pressure sensitive adhesives: an ultrasmall angle X-ray study

“…As 11 minima have been observed at one side in the scattering curves, n has to exceed 2i ¼ 22: For all film-punch distances the relation 210 nm onD y0 o257 nm is valid. In the context of adhesive debonding, the slits might be embodied by elongated micro-bubbles embedded in the polymeric fibrils [5]. The existence of microbubbles was proposed in theory [6].…”

“…Nevertheless, investigations by conventional microscopy are restricted towards small length scales by the optical resolution limit. In order to overcome this limit, we applied in situ ultrasmall angle X-ray scattering (USAX) during the tack test [5].…”

Pressure‐Sensitive Adhesive Blend Films for Low‐Tack Applications

“…The second, polystyrene (PS), increases cohesion and yields structured films, due to the incompatibility with PnBA. The tacky component, PnBA, was used in several investigations in the past 8, 18–20. The nonadhesive component, PS, was chosen as a standard polymer with well‐characterized physical parameters, including the polymer–polymer interaction parameter with PnBA, which characterizes the incompatibility.…”