Resistance Assessment
Standard laboratory procedures determine the maximum sliding or tearing force that an adhesive bond or coating can withstand before failing. Performing shear threshold measurement ensures that laminated paperboard layers or labels will not slide and separate when subjected to heavy loads during transit or storage. This testing is essential for certifying the structural performance of heavy-duty boxes.
Test Mechanism
The testing apparatus secures a laminated specimen between a fixed clamp and a motorized pulling jaw, then applies a gradually increasing parallel force. Dynamic load cells record the exact force at which the first sign of sliding or cohesive failure occurs within the adhesive joint. This test can be conducted at elevated temperatures or humidities to simulate the environmental conditions of shipping containers in tropical regions.
Software plots the stress-strain curve to identify whether the failure is adhesive, meaning the glue separated from the paper, or cohesive, meaning the glue layer split internally.
Process Application
Inadequate adhesive curing or uneven adhesive application results in a low shear threshold, which can cause cartons to fall apart under stacking pressure. Using the recorded data, operators adjust the coat weight or drying parameters of the laminator to guarantee reliable bond strength.
