Effect of Peel Side on Optimum Condition for Measuring Flexible Film Peel Strength in T-Peel Adhesion Test

Abstract Standardized methods for conducting a T-peel test have been well established for rigid materials, but are not suitable for flexible film because of variations in peel strength. The purpose of this paper is to provide an experimental procedure for a T-peel adhesion test and determine optimum conditions by considering the effect from alternate peel sides. A new testing apparatus is developed to solve the variation problem of using standardized methods for flexible packaging film. The optimum conditions are achieved using a parameter design method. The dynamic signal-to-noise ratio provides the optimum condition, as it has a minimum variation of peel strength evaluated from the peel side of the aluminum (Al) and cast polypropylene (CPP) layers. An experimental design is employed using an orthogonal array with four control factors consisting of peel angle, peel speed, data region, and spring thickness. The variation caused by the different peel surfaces of each specimen is investigated to observe which peel side gives the best condition for the T-peel test. Three optimum conditions for flexible film are discussed: the aluminum peel side condition, the CPP peel side condition, and the harmonized condition. Based on the signal-to-noise ratio (SNR) used to evaluate the improved condition in a confirmation test, the CPP peel side has the highest SNR, followed by the aluminum peel side, and then the harmonized condition. The SNR for the CPP peel side condition increased by 22 % from the aluminum peel side condition; thus, it is advised that the CPP peel side condition be used. The SNR of the harmonized condition is lower than the CPP and aluminum conditions, but it provides a convenient design that can be used without regard for peel side.