Bond Adhesion
Adhesion failure between a polymer extrusion and a paper substrate occurs when surface energy dips below the threshold required for molecular wetting. Dynamic scott bond measures internal ply separation resistance under a high speed impact stroke, separating standard static tensile tests from actual converting performance. Mill laboratories evaluate this property using a pendulum hammer that strikes a laminated sample at a fixed velocity, recording the energy consumed during total delamination.
Low surface tension on the paper board prevents molten polyethylene from anchoring into the cellulose fibres during extrusion coating, creating weak zones that fail during high speed cartoning operations. Converters adjust corona discharge intensity on the extrusion line to raise surface energy above thirty eight dynes per centimeter, ensuring permanent lamination across folding boxboard production runs.
Impact Resistance
High speed packaging lines subject laminated folding cartons to sudden mechanical shock during erect, fill, and seal cycles, demanding high internal bond strength to prevent structural delamination. Dynamic scott bond provides converters with quantitative data regarding how well multi layer paperboards withstand rapid delamination forces without shearing apart mid wall. Brittle starch adhesive layers inside recycled paperboard react poorly to sudden impact forces, causing internal ply failure when cartons undergo high speed compression on automated packing machinery.
Selecting virgin chemical pulp furnishes for the middle layers improves internal fibre entanglement, absorbing shock waves that would otherwise split the substrate apart.
Delamination Threshold
Paperboard packaging destined for liquid holding requires predictable internal bond values to withstand hydraulic pressure from hot fill beverages without swelling or separating at the glue lines. Dynamic scott bond establishes the outer boundaries of structural integrity for barrier coated substrates before moisture migration weakens the internal hydrogen bonds between cellulose sheets. Excessive refining during stock preparation increases fibre-to-fibre contact area and raises internal bond values, but excessive beating reduces tearing resistance and dimensional stability across offset printing presses.
Production engineers balance refining energy against internal strength requirements to maintain sufficient ply bond without sacrificing stiffness in the final packaging grade.
