Elastomerics Blog

Stockwell Elastomerics can apply adhesives to rubber materials and fabricated custom gaskets. Many of these gasket materials are specialty silicone or fluorosilicone, and many silicone gaskets use a pressure sensitive adhesive (PSA) backing for peel-and-stick installation. These adhesive backed gaskets can promote faster and less expensive product assembly, and Stockwell Elastomerics is ready to help engineers select the best adhesive for their applications.

Adhesion and Cohesion Explained

When specifying adhesives for rubber materials, it’s important to understand the difference between adhesion and cohesion. Adhesion is the force of the attraction between the adhesive and the substrate. In other words, it determines how well the adhesive sticks to the gasket material. Cohesion refers to the internal strength of the adhesive instead. It determines how well the adhesive holds together once applied, and it may be for the structural integrity of the adhesive bond.

Engineers don’t want adhesives that will peel off due to adhesive failure, so matching the adhesive’s chemistry to the type of rubber is critical. At the same time, engineers don’t want adhesives that will fail internally under load or temperature extremes. That’s why gaskets subjected to flexing, compression, and shear need adhesives with sufficient cohesive strength to resist cracking, tearing, or flow under mechanical stress and temperature cycling.

Peel, Lap Shear, and Tensile Testing for Adhesives

Peel, lap shear, and tensile tests are used to measure the strength and performance of adhesives. Peel testing measures adhesion, tensile testing measures cohesion, and lap shear testing measures both. View the adhesive data sheets for values that are reported.

• Peel testing measures the force required to peel an adhesive from a substrate. The force direction is angular (90° or 180°), and the results are given in newtons per millimeter (N/mm) or pounds per inch (lb/in).
• Lap shear testing measures the shear strength of an adhesive between two overlapping materials. The force direction is parallel (shear), and the units of measure are megapascals (MPa) or pounds per square inch.
• Tensile testing measures the maximum force that an adhesive can withstand when pulled apart in tension. The force direction is perpendicular, and the units of measure are MPa or psi.

Contact Stockwell Elastomerics for more information and help with adhesive selection for custom gaskets and pads.