Rheology is the study of how things flow and as such is a lot more in depth than simple viscometry which is really only useful as a quality control test.

An understanding of flow behaviour is essential in Adhesives and Coating Technology as a materials flow characteristics will control a number of important properties like.

• In can stability
• Application e.g. spray, roller, slot coater, dip
• Setting characteristics e.g. Hot Melts.
• Sagging and flow brush marks and coating lines.

Essentially materials exhibit four main types of flow characteristics.

• Newtonian
• Pseudoplastic
• Dilatent
• Thixotropic

Thixotropic is a special form of Pseudoplastic flow. Which of these types of flow your adhesive or coating exhibits will dramatically affect how it applies to the substrate and in many coatings how it will behave after application while it is drying or curing.

Usually the wrong Rheology means it is difficult or impossible to apply the material or it sags or flows after application. Occasionally the wrong Rheology can have serious consequences. Adhesives which are Gravure applied need to be psuedoplastic. If they change during application due to prolonged shear they can become Dilatent resulting in cell clogging and reduced coat weight leading to cohesive failure in the final structure.

If you want to learn how Rheology affects the way your products behave and how to formulate the desired Rheological behaviour contact ATAC UK Ltd we can run short course for your staff at your premises. Additionally if you have a Rheology based problem we can provide expert assistance by.

• Defining the Rheology of your existing system.
• Identifying the required Rheology for the process.
• Providing help in formulating the desired Rheology.