Wednesday  |  Carnegie III  |  03:10 PM–03:30 PM

#13700, Characterization of Rate-Dependent Failure Properties of Pressure Sensitive Adhesives

Pressure sensitive adhesives (PSAs) are commonly used in applications where the adhesive is required to withstand impact events, such as the consumer electronic device, aerospace, and automotive industries. Due to the viscoelastic mechanical behavior of PSAs, it is necessary to characterize these materials using strain rates and temperatures that are relevant to the intended application. This often proves challenging as the application design typically entails complex loading and deformation modes that are difficult and costly to measure directly or replicate in coupon level testing. For this reason, it is desirable to develop coupon level test methods that isolate specific deformation modes, such as tension and shear, to characterize the failure properties of the adhesive in these deformation modes at relevant rates and temperatures.

In this work, test methods which isolate through-thickness tension and simple shear deformation and failure modes are presented. The tests methods are compatible with both instrumented drop towers for test speeds on the order of 1 m/s and standard screw-driven load frames for test speeds on the order of 10 mm/s or slower. The methods are evaluated to understand the repeatability and reproducibility of the data generated. The effects of test rate and temperature on the mechanical and failure properties of PSAs are then explored. Further, in conjunction with rheological analysis, the time-temperature superposition principle is implemented to quantify failure properties of the adhesives at effective rates that could not be tested directly with the instruments. The viability of the time-temperature superposition method is investigated by comparing results from high-speed tests run on the drop tower and slow-speed tests run on the load frame shifted to effective rates based on the test temperature and the shift factors determined from the rheological analysis. When applicable, this approach provides potential cost savings as it allows for PSAs to be tested at conditions equivalent to impact rates without investment in specialized impact testing equipment and associated data analysis.

Michael Wald   3M Company
Aaron Hedegaard   3M Company
Ryan Birringer   3M Company
Tobias Waffenschmidt   3M Deutschland GmbH
Nelson Goncalves Pimentel   3M Deutschland GmbH