The influence of test temperature on pressure-sensitive adhesive products
Views : 2702
Update time : 2021-04-02 08:27:35
When the 180° peel strength test is performed at different temperatures, not only the measured peel strength values are very different, but also the type of damage is also different. Under the same other test conditions, the 180° peel strength test value of a typical pressure-sensitive adhesive tape and the change curve of the type of damage that occur with the test temperature are shown in the figure. Cohesive failure of the adhesive layer occurs in the test in the high temperature zone, and the peel strength value mainly depends on the cohesive strength of the pressure-sensitive adhesive (A zone); as the test temperature decreases, the cohesive strength of the pressure-sensitive adhesive increases, and the peel strength appears first. A maximum value, and because the cohesive force of the adhesive layer gradually exceeds the interface adhesion force, the transition to the interface adhesion failure occurs (mixed failure area B), and then the complete interface adhesion failure area (section BC), in this area The internal peel strength increases rapidly with the decrease of the test temperature, until the second maximum (zone C) appears, followed by the stick-slip peeling zone, and the peel strength decreases rapidly with the decrease of the test temperature.
The change in the peel strength test of pressure-sensitive adhesive products with the decrease of the peeling temperature is also determined by the viscoelastic behavior of the pressure-sensitive adhesive. The decrease (or increase) of the test temperature and the increase (or decrease) of the peeling speed have the same rules for the effect of the peel strength and failure type. The two are equivalent. The two transitions of the change curve in the above figure also reflect the transition of the pressure-sensitive adhesive from the viscous fluid state to the highly elastic state and the transition from the highly elastic state to the exfoliated state. The temperature corresponding to the second maximum value is the peeling transition temperature Tg of the pressure-sensitive adhesive, and the transition temperature T from the cohesive failure of the adhesive layer to the interface adhesion failure is called the splitting temperature. Ts is also a useful performance characterization of pressure-sensitive adhesives. It can be considered that the Tg here is an important characterization of the low temperature resistance of the pressure-sensitive adhesive product: the lower the Tg, the better the low temperature resistance of the pressure-sensitive adhesive product. And Ts is an important characterization of the high temperature resistance of pressure-sensitive adhesive products: the higher the Ts, the better the high temperature resistance of the pressure-sensitive adhesive products. In fact, the temperature range between Tg and Ts is the actual temperature range in which pressure-sensitive adhesive products can be used.