A constitutive equation of pressure sensitive adhesives is described. The material characteristics of pressure sensitive adhesives indicate viscoelasticity and rubber-elasticity. The effective large deformation simulation of pressure sensitive adhesives should be inquantitative consistency with practical behavior. For the quantitative consistent simulation, the constitutive equation including every material characteristicis indispensable. This paper proposes the constitutive equation for pressure sensitive adhesives, which covers viscoelasticity and rubber-elasticity, and tests the validity of the proposed constitutive equation by using comparison with experiment and computational results.

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Relationship between adhesion properties and molecular mobility of styrene triblock and diblock copolymer blends was investigated in detail. For this purpose, polystyrene-brock-polyisoprene-block-polystyrene triblock and polystyrene-brock-polyisoprene diblock copolymers were used and thediblock content was varied from 0 to 100wt%. All blends formed the sea-island structure in which spherical polystyrene domains were dispersed in polyisoprene matrix and mean domain size was approximately 20nm. The domain size was slightly affected by the diblock content. The fracture stress and strain measured by a tensile test decreased and the molecular mobility measured by a1H pulse nuclear magnetic resonance analysis increased with an increase of diblock content. The tack as adhesion property increased with an increase of diblock content below 70wt%, then decreased over 70wt%. The cohesive strength decreased and the interfacial adhesion increased with an increase of diblock content. The tack increases by the development of cohesive strength and interfacial adhesion. Therefore, the tack showed the maximum at the optimum contribution balance between cohesive strength and interfacial adhesion.

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