Morphological studies on the adhesion mechanism of pressure-sensitive adhesives

The breaking process of the thin film of pressure‐sensitive adhesives which are blends of natural rubber and the pentaerythritol ester of hydrogenated rosin and its surface structure after peeling off have been studied by electron microscopy. The dynamic observation of breaking process of the adhesives during the peeling has also been done by optical microscopy. The fibril structure with diameter of 50‐100 Å was observed under the breaking process of the thin film and on the surface after peeling off the adhesive tape consisting of 40‐60 wt % of resin. The previously proposed mechanism of adhesion which is based on the dynamic behaviors of fibrils and easy flow regions in the adhesives is confirmed by the electron microscopic observation.