Tensile Strain Measurement in Recycled Paperboard Grades
Recycled paperboard strain measurement requires direct optical extensometry under ISO 1924-3 to isolate true sheet elongation from clamp slippage.
Stretch at Break
Elongation Capacity
Tensile assessment calculates the percentage increase in length a substrate undergoes before structural failure occurs under a constant load. Stretch at break identifies the maximum strain a paper or plastic film sustains during a controlled pull until the material snaps. This value reveals the ductility of a sheet, informing how the substrate reacts to high-speed converting forces without rupturing.
Mechanical Behavior
Internal fibre orientation and chemical additives determine how a paper web distributes stress throughout its surface area during the manufacturing stage. Higher values indicate that the substrate possesses significant capacity to absorb energy during sudden web tension spikes on a flexographic press. Low figures signal brittle behavior, which frequently results in snap-offs during rapid winding or folding operations.
Consistent results depend on maintaining stable moisture content, because humidity fluctuations alter the pliability of the cellulose matrix.
Material Utility
Packaging engineers select specific substrates based on these measurements to ensure the final pouch or carton withstands the rigors of automated filling lines. Vertical integration of this metric allows converters to predict the point of rupture when a machine introduces mechanical strain through constant speed adjustments. A balance between stiffness and ductility remains necessary to prevent jamming while maintaining the integrity of the barrier protection.
Overestimating the allowance for deformation leads to deformed seals, while underestimating this limit produces frequent line downtime due to structural fracture.