Polymer Softening
Chemical modification alters the rigid molecular arrangement of wood pulp to increase the flexibility of the resulting sheet or film. Under specific thermal or chemical treatment, cellulosic plasticization reduces the hydrogen bonding between cellulose chains, which allows the fibres to slide more easily under tension. This process converts a brittle paper barrier into a formable substrate suitable for deep-draw packaging applications.
The treatment ceases to be effective if the temperature drops below the glass transition point of the modified polymer.
Fibre Modification
Introducing external agents such as water or glycol into the cellulose matrix breaks the highly crystalline areas of the fibre. This molecular restructuring decreases the stiffness of the paperboard while increasing its elongation before rupture.
Structural Elongation
Manufacturing processes that involve deep stamping or three-dimensional forming of paper trays rely on this increased ductility to prevent tearing. Standard uncoated paper would fail immediately under the tensile forces of a forming mold, whereas plasticized board stretches into the required shape without fracturing. The retention of this pliable state depends on the moisture content remaining within a specified tolerance during storage.
If the material dries out completely, the fibres re-establish their rigid crystalline networks and lose their formability.
