Measurements of Interfacial Strength from the Blister Test

Measurements of the interfacial properties between an elastic tape and poly(methyl methylcrylate) substrates were carried out using a circular blister test. All properties, including adhesive fracture energy G_a, residual stress σ_o and the elastic modulus of the tapes can be deduced in a single test. Three different approaches have been adopted to analyze the relations between blister radius, blister height, and the pressure inside the blister. A comparison of the calculated results from these methods is provided and the details of the fracture process are discussed. Effect of the volume flowrate of the injected fluid was investigated as well. Results show that the deduced value of G_a is about 3.0 ± 0.5 J/m² and the elastic modulus of tape is 330 ± 40 MPa, in good agreement with that determined from the tensile test. The fracture time is reduced from 4000 to 700 s for a flowrate of the injected fluid from 0.05 to 0.5 mL/h. In all cases, quasistatic deformation of the blister is found valid and the effect of the flowrates on the failure mechanics is not significant for the present study. However, one should take the dynamic deformation effect of the blister into consideration when the flowrate is too high.