AbstractCellophane sheets were coated with acrylic latex polymers, pressed together in pairs at elevated temperature, and peeled apart at constant relative humidity and temperature. The effect of the rate of peeling and the adhesive layer thickness upon the peeling force was investigated. When a laminate is peeled, the steady‐state peeling force is generally not constant, but the frequency distribution of the instantaneously measured steady state force values is Gaussian. The mean value of the force is well defined and is equal to the median force. This type of variability is probably due to sample nonuniformity. The second type of variability in the steady‐state peeling force is inherent in the binder/substrate system. Here failure in the glue line is not initiated continuously but periodically, and the failure propagates faster than the rate of peeling. Consequently the steady‐state peeling force passes through well‐defined maxima and minima. It was also observed that the distance between two adjacent maxima or minima was constant and insensitive to the testing rate. When the force is randomly oscillating, the mean force generally either increases with the rate of testing or is insensitive to it. It always increases with the thickness of the adhesive layer. A special case was extensively investigated where at low rates there was cohesive failure and the peeling force increased with the testing rate, while at high rates the force was rate independent and produced adhesive failure. The cohesive failure force could be represented by a single master curve when the force was plotted againstRtan, whereRis the peeling rate,tais the thickness of the adhesive layer, and the exponentnis a constant characteristic of the system. When the binder/substrate system gives a steady‐state force with well‐defined periodicity, the maxima and minima in the force generally decrease with increasing testing rate. The periodicity of the steady‐state force can be eliminated by having a rough instead of smooth binder/substr
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