How to formulate for high shear strength in adhesives?
Last update on Jan 14, 2026
Shear strength quantifies an adhesive’s capacity to withstand stresses applied parallel to the bond interface. It reflects the cohesive integrity of the adhesive film and the interfacial adhesion under lateral loading. It indicates how well the joint resists displacement when subjected to sliding or shear forces.
Shear strength vs. peel strength vs. tensile strength
Tensile strength refers to an adhesive’s ability to withstand forces applied perpendicular to the bond line. This means pulling the substrates directly apart. It measures the maximum stress the adhesive can endure before failure under pure tension.
Peel strength describes resistance to forces that separate bonded surfaces at a defined angle (commonly 90° or 180°). Peel stress is highly localized along the leading edge of the joint. It often involves at least one flexible substrate. This generates concentrated stress that can challenge interfacial adhesion at the bond edge.
To summarize:
Strength type | Stress direction | Mechanical context | Primary concern |
Shear strength | Parallel to bond line | Resists sliding or lateral forces across bond interface | Cohesive/interfacial integrity in lateral load |
Tensile strength | Perpendicular to bond line | Resists direct pulling forces separating bonded surfaces | Bond integrity under direct axial pull |
Peel strength | Localized at bond edge angle | Separates surfaces by peeling, often one flexible substrate | Stress concentration and edge adhesion |
It is crucial to take into account all these 3 parameters to understand how an adhesive will perform under diverse mechanical stress scenarios.
Pre-requisites
For formulators, two key considerations are:
- Cohesive integrity of the adhesive: High shear strength requires the adhesive to maintain internal cohesion under lateral load.
- Strong interfacial adhesion: Shear failure often occurs at the adhesive–substrate interface if adhesion is poor.
Formulation strategies
- (n.d.). Shear Strength vs. Tensile Strength: How to Choose the Right Adhesive for Your Application. Seal Bond.
- Cephas. (n.d.). Stressed Out? Understanding Shear and Peel Strengths for Adhesives. TAPECON.
- Edward Petrie. (n.d.). Acrylic Pressure-Sensitive Adhesives (PSAs): How to Formulate Them?. SpecialChem.
- Blacknall and Russell. (n.d.). Adhesive Performance Explained: Tack, Peel Strength, Shear and Cohesion. Big Picture.
- (n.d.). Bonding and Assembly. 3M.
- SpecialChem. (n.d.). Enhancing polymer properties through crosslinking.