Peel Grips

The adhesives industry continues to grow above historical trends, fueled by modern manufacturing strategies such as lightweighting, multi-material design, and automated assembly processes. In 2016, the global market for adhesives stood at roughly $25 billion USD with more than 10 million tons of output, and demand has continued to expand as manufacturers increasingly replace mechanical fasteners with bonded joints. Adhesive bonding allows for improved stress distribution, reduced structural weight, cleaner aesthetics, and more efficient production workflows, making it a preferred joining method across aerospace, automotive, electronics, packaging, and construction industries.

As adhesive formulations have diversified — ranging from pressure-sensitive tapes to structural epoxies and acrylic systems — standardized testing methods have become essential for comparing performance across materials and applications. Among these, peel testing plays a critical role because it evaluates how a bonded joint behaves under progressive separation, which closely reflects many real-world service conditions. Unlike pure tensile or shear tests, peel testing introduces bending stresses that concentrate force at the bond line, making the method particularly sensitive to surface preparation, adhesive thickness, cure conditions, and substrate stiffness.

The most common and straightforward peel procedures involve separating a flexible adherend from a substrate at either a 90-degree or 180-degree angle. These configurations are widely used for evaluating tapes, films, labels, protective layers, and flexible laminates. In a 90-degree peel test, the bonded material is pulled perpendicular to the substrate, simulating applications where a layer is lifted or removed from a surface. In the 180-degree configuration, the material is folded back over itself and peeled in line with the substrate, producing a more uniform stress distribution along the bond interface and often reducing the influence of bending stiffness.

A third widely used configuration is the T-peel test, which is typically applied when two flexible adherends are bonded together rather than attached to a rigid surface. In this setup, both ends of the specimen are pulled apart symmetrically, forming a “T” shape as the bond progressively separates. The T-peel method is commonly used for evaluating laminates, flexible packaging materials, bonded textiles, and other assemblies where both layers deform during testing. Because both adherends bend during loading, specimen stiffness and geometry play a more significant role in the measured peel force than in 90- or 180-degree configurations.