Effect of the rheological properties of industrial hot-melt and pressure-sensitive adhesives on the peel behavior

Three factors govern the adhesion properties of hot-melt and pressure-sensi tive adhesives: (1) thermodynamic interfacial properties (Dupre adhesion en ergy); (2) interfacial losses due to specific interactions; and (3) viscoel astic losses in the bulk related to the rheological properties of the adhes ive. In the present paper, we focus on the main factor in the adhesion prop erties, which is the viscoelastic factor. We extend in this paper the resul ts obtained on a series of model adhesives to the case of industrial formul ations: one SIS triblock copolymer-based PSA formulation and one EVA copoly mer-based hot-melt formulation. After studying the rheologcal properties of these adhesives over a wide frequency range using time-temperature equival ence, we present data obtained on peel tests at various temperatures. As wi th model adhesives, the peel rate- temperature equivalence leads to the sam e shift factors as rheology. The experiments demonstrate that there is a on e-to-one relationship between the cohesive fracture domain and the terminal region of relaxation exhibited in rheological testing. The first interfaci al fracture mode is related to the rubbery plateau, and the brittle interfa cial fracture mode observed at high peel rates to the glassy behavior exhib ited at very high frequencies in rheological measurements.