To insure that adhesives and sealants function well
during their application and end-use, the formulator must be able to control the flow
properties of the product. The challenge that the formulator faces is that the adhesive or
sealant may need different flow characteristics at different times.
Adhesive and sealant manufacturers employ rheological
additives for thickening and to prevent sag of their products. In practice, rheological
additives may provide benefits in addition to viscosity or flow control. When properly
formulated into adhesives and sealants, rheological additives improve several properties of the formulation.
In practice, formulators have a variety of additives
available to manipulate these properties. This article will review this technology with the
emphasis on the development of non-sag or thixotropic products. However, certain "thickening
agents" that are not classical thixotropes will also be discussed.