Cellulosic Microfibril Moisture Binding Mechanisms in Packaging
Microfibril moisture binding follows GAB sorption kinetics where mesopore condensation above M0 plasticizes fiber networks, requiring crosslinking to preserve barriers.
Out of Plane Tensile Strength
Bond Strength
Strength property measures the force required to pull a paper or board sample apart in a direction perpendicular to its surface. Out of plane tensile strength indicates the internal bond quality between the different layers of the sheet. It is a critical metric for determining the resistance of a board to delamination during high-speed processing.
Testing Procedure
Testing involves sticking the surfaces of a small sample to two metal platens and pulling them apart until the internal structure fails. The result is expressed in kilopascals and indicates the distribution of fibres and binders through the thickness of the material. A low value suggests that the material may split when subjected to the high-tack inks used in offset printing.
This property is heavily influenced by the refining of the pulp and the wet-pressing stage of the paper machine.
Press Performance
Multi-ply boards are particularly susceptible to failures in this direction if the layers are not properly bonded together. High-speed folding carton lines generate significant peeling forces that can cause the board to separate at the corners. Improving this strength allows for the use of more aggressive adhesives and faster production speeds.
It is also an essential factor in the performance of easy-open packaging features. Surface treatments can enhance the bond between the top coating and the base sheet to prevent picking.