ABSTRACT
Rheology is the science of deformation and flow of the matter due to the application of a force. Most rheological tests involve applying a force to a material and measuring its flow or change in shape. Rheological characterization is useful to study the flowability and viscoelastic properties of adhesive materials. This chapter reviews and discusses the rheological behavior of protein-based adhesives and the effect on their bonding properties. Rheological characterization allows the analysis of the internal structure of the adhesives when they are modified by both physical and chemical processes. Most of the discussion focuses on soy- based and cottonseed-based adhesives modified by heat treatments, varying pH, enzymatic treatment and blending with commercial latex. Rheological characterization may also provide operational parameters for the preparation of wood composites. As an example, adhesives with a high flow point value will not flow easily on the surface of wood particles, hindering the dispersion of the adhesive and wetting of such particles.
