Characterization of adhesive curing reactions using rapid heat rheology

Understanding the curing mechanisms of adhesives presents basic knowledge of planning adhesive application and bonding processes. The demand for short manufacturing cycle times drives the development of rapid curing adhesives. Furthermore, the processing parameters influence both: the process time and the adhesive properties. This motivates upgrading the boundary conditions of common rheometric measurement methodologies to reflect application process parameters. For this purpose, it is imperative to investigate the interaction of fast-curing adhesive, rheometric method and measuring device setup. Influences on the measurement accuracy caused by highly dynamic heating processes must be minimized or compensated for in the evaluation of the results. At the same time, knowledge must be acquired on how to determine the material-specific process limits. The resulting systematics for the development of fast-curing adhesives and for the planning of adhesive manufacturing processes will enable a significant industrial spread of fast curing with all its advantages. This paper provides a first step in this process by investigating the curing behavior of a thermal rapid curing one component polyurethane adhesive at heating rates of 50 and 100 K/min. The results for the evolution of the shear modulus are compared to the results from standard rheometric methods.