Optimizing Chemi-Thermomechanical Pulp Core Fractions for Lightweight Board
Balancing middle ply mechanical pulp freeness preserves sheet caliper and bending resistance while controlling delamination under high-speed scoring.
DIN 53121 Elastic Modulus
Bending Resistance
Standardized metric for determining the modulus of elasticity of paper and board by calculating the relationship between applied stress and resulting strain during a bending test. Testing according to din 53121 elastic modulus provides a fundamental value for the material stiffness that is independent of the specimen thickness. The method employs either a two point or four point bending setup to measure the force required to deflect the substrate.
It is particularly relevant for folding boxboard where the stiffness of the outer plies dictates the creasing performance.
Industrial Application
Converting operations rely on accurate stiffness data to predict how a board will behave on a high speed filling line. High values for the din 53121 elastic modulus suggest a material that will resist bulging when the finished carton is filled with product. Because paper is an orthotropic material, the modulus must be measured in both the machine direction and the cross direction to fully characterize its performance.
Modern paper machines use this information to adjust the fibre orientation and starch application during production.
Test Boundary
Results are only valid within the elastic region. This ensures the material returns to its original shape after the load is removed.