Thixotropic Rebuild Kinetics Governing High Speed Slot Die Coating Instabilities
Thixotropic rebuild delay shifts slot die bead rupture limits during high speed web acceleration.
Yield Stress Resurgence
Meaning
Material properties sometimes recover their resistance to flow after the cessation of shear during a resting phase. Yield stress resurgence describes the increase in the minimum force required to initiate movement as a complex fluid rebuilds its internal structure. This phenomenon is common in thixotropic slurries used in battery manufacturing and mineral processing.
Network Restoration
Interparticle forces create a weak lattice that prevents flow at low stress levels. Once a pump stops, yield stress resurgence begins as particles find low energy positions and bond together again. The rate of this recovery determines how long a production line can sit idle before the pipes become blocked.
Storage Stability
Long periods of rest allow the internal structure to become significantly stronger than it was during the initial mixing phase. If the yield stress resurgence is too high, the fluid might not pour or pump after being stored in a tank. Formulations are often adjusted to limit this strength to a level that industrial motors can overcome, preventing the permanent seizure of stagnant lines.
Pumping Restart
Mechanical systems must provide enough initial torque to break the static structure of the fluid. Yield stress resurgence dictates the power requirements for restarting a line after a maintenance shutdown. Testing this property at the pilot scale prevents the failure of full-scale production pumps that lack the necessary startup pressure.