What is thixotropic index and why is it measured?
What is thixotropic index and why is it measured? Ablestik defines thixotropic index as the ratio of the viscosity at 0.5 rpm and viscosity at 5.0 rpm at 25°C typically using a cone and plate viscometer. Using the pressure-dispensing model, the viscosity at 0.5 rpm represents the adhesive at rest, and less dripping is associated with a higher viscosity at 0.5 rpm. The viscosity at 5.0 rpm represents the adhesive rheological behavior when it is exposed to forces associated with dispensing through a needle or nozzle. Less tailing is associated with a lower viscosity at 5.0 rpm. In general, a thixotropic index of 3.0 or greater has shown to give good high-speed needle dispensing with minimal dripping and tailing.
