Mechanical Refining Impact on Multi Ply Boxboard Z Direction Tensile Development
Controlled low energy refining of middle ply mechanical pulp yields superior Z direction tensile development without caliper loss in multi ply boxboard.
Microfibrillar Delamination
Structural Separation
Mechanical and chemical processing splits the layered internal wall of cellulose fibers, separating concentric microfibril layers without severing the main fiber axis. This internal structural separation, termed microfibrillar delamination, increases fiber wall flexibility and water retention capacity during pulping. Paper sheets made from delaminated fibers exhibit high density and exceptional tensile strength.
Shearing Force
High-pressure homogenizers and microfluidizers subject pulp suspensions to extreme fluid shear and cavitation forces to induce structural splitting. Concentrated mechanical energy forces water molecules between concentric lamellae, disrupting inter-crystalline hydrogen bonding networks that hold sub-fiber elements together. Controlled microfibrillar delamination exposes immense specific surface area, transforming rigid wood pulp into a highly viscous gel containing nanoscale cellulose fibrils.
Mill operators monitor pressure drops and passage counts through microfluidization chambers to target specific levels of internal wall separation. Proper delamination maximizes inter-fiber bonding potential during paper sheet formation while avoiding excessive mechanical degradation of individual cellulose polymer chains.
Viscosity Threshold
Extensive internal delamination dramatically increases slurry viscosity, creating fluid handling challenges in stock preparation systems. Dewatering rates on the paper machine wire drop significantly as nanoscale fibrils entrap free water within the wet web. Processing equipment must manage high pumping resistance to maintain continuous production.