Energy Input
Mechanical forces applied to a mixture of water and paper during testing quantify the energy required to return a solid sheet to a liquid fiber suspension. Laboratory disintegration shear is the specific cutting and rubbing action generated by the blades of a test pulper. It overcomes the adhesive forces and mechanical interlocking that hold the paper together.
Measuring this force helps predict how easily a new packaging design will break down in a commercial mill.
Fiber Separation
Intense mechanical action is required to defiber wet-strength papers or boards with heavy polymer coatings. High levels of laboratory disintegration shear can reduce the length of the fibers if the rotor speed is not correctly calibrated. This shear is necessary to separate the cellulose from the plastic layers in laminated materials.
The intensity of the force is measured in kilowatt-hours per ton or simply by the duration of the agitation. Excessive force can generate heat that softens adhesives and makes them harder to screen.
Pulp Integrity
High shear levels often damage the fibers and lower the final strength properties. Selecting the right shear level is a balance between complete defibering and fiber preservation. This metric is a standard part of the recyclability assessment for new packaging.
