Uniaxial Extensional Rheology of Associating Polymers: from Processing to Performance

Polymers which include associating groups show increased performance characteristics over the base backbone polymer. The tunable properties of associating polymers are desirable for a wide range of applications, including as self-healing materials. However, there is typically a loss of processability for strongly associating polymers. In this work, we use filament stretching uniaxial extension to probe the processing window of strongly associating polymers. We show that, processing is limited by melt fracture in a wide range of Weissenberg numbers. The presence of entanglements increases the level of processability both in terms of the maximum Hencky strain before failure and the minimum achievable strain at low temperatures. Furthermore, the mechanical performance of associating polymers is confirmed to depend strongly on the associating group strength. Both the processability and performance of associating polymers can be captured by a spectrum of relaxation timescales related to the polymer backbone and various states of the associating groups. By reducing the critical behaviors of associating polymers to key timescales, clear design and processing parameters can be addressed in terms of fundamental physics.