Structural Analysis of Pressure-Sensitive Adhesive using Pulse NMR

Abstract

The useful data analysis techniques of the ¹ H pulse nuclear magnetic resonance（pulse NMR）measurement were discussed in order to clarify the tackiness mechanism of pressure-sensitive adhesive（PSA）. From the analysis of relaxation time for base polymer/tackifier system, the developmentof cohesive strength of PSA, the solubility of tackifier in base polymer and the phase separated structurecould be estimated. The relaxation spectrum shows clearly the existence of components whichraise the interfacial adhesion and the cohesive strength of PSA independently for base polymer/tackifiersystem, respectively. The difference spectrum indicates clearly the relaxation time range in whichthe cohesive strength of the base polymer was developed by the tackifier addition. The linear relationshipbetween the crosslinking density calculated from the equilibrium degree of swelling and therelaxation time was confirmed for crosslinked polyurethane pressure-sensitive adhesive. It was foundthat the crosslinking density is able to be estimated from the relaxation time.