Understanding Hot Melt Adhesive Rheology

Hot melt adhesives are a popular adhesive choice for many applications. Easy to apply, they can increase throughput, enabling plants to meet high production demands. Additionally, by containing little to no solvents, these adhesives aid in plants’ sustainability initiatives. Yet it’s also important to understand how these adhesives work in order to ensure adhesive success. Take a look at what rheology is and how it impacts performance. What is Rheology? Rheology is the study of the flow of materials. For hot melt adhesives, rheology plays an important role in determining how they will perform for a specific application. It relates to how well the adhesive will flow, wet out and adhere to a certain substrate. In particular, adhesive elasticity, viscosity and modulus are related to its rheology.

• Elasticity: the adhesive’s ability to store energy and use that energy to retain original shape when moved
• Viscosity: the adhesive’s resistance to flow
• Modulus: the adhesive’s flexibility levels after it sets

How is Hot Melt Adhesive Rheology Determined? Common tests to determine hot melt adhesive rheology include conducting dynamic oscillatory measurements. This method involves twisting the material at different frequencies and amplitudes and studying the adhesive’s behavior. It helps give insight into the adhesive’s flow properties in order to predict how it will perform for an application. Understanding an adhesive’s rheology not only gives insight into its performance, it also can help manufacturers:

• Make adhesive improvements
• Customize adhesives for certain applications
• Develop new products with different elasticity and viscosity measurements

Smart Adhesives with Smart Rheology For over 125 years, Bostik has manufactured smart hot melt adhesives designed to improve operational efficiencies and overall product quality. Contact us today for more information on our hot melt adhesives.