Material Toughness Measure
The absorption of mechanical force during the deformation of a fiber network determines the impact resistance of packaging material. High levels of energetic dissipation prevent the sudden, catastrophic failure of paperboard under dynamic loads during drop tests.
Fiber Network Action
Tensile and compressive forces distribute throughout the fibrous sheet, stretching the polymer chains of cellulose and hemicellulose. An energetic dissipation occurs as these internal hydrogen bonds break and reform under stress, converting mechanical energy into heat. Cohesive failure between the plies of multi-ply board also absorbs a portion of the impact, protecting the packaged goods from damage.
Boards with high tensile stiffness but low stretch tend to fail quickly because they cannot spread the localized forces over a wider area.
Testing And Calibration
Laboratory instruments measure the energy absorbed during rapid tearing or puncture to quantify this structural performance. Out-of-plane tear testers and drop-weight impact towers provide data on how the board behaves under realistic shipping conditions. Adjusting the ratio of softwood to hardwood pulp modifies the internal bonding strength, allowing papermakers to optimize this capacity.
Boards with a higher proportion of long softwood fibers demonstrate superior ability to withstand sudden shocks without tearing or bursting.
