Discrepancies in High Yield Pulp Mass Balance Calculations across Multi Ply Board Mills
High yield pulp mass balances fail when mills exclude white water solubles and moisture variation, exposing buyers to chain of custody audit liabilities.
Cationic Starch Retention
Polymer Binding Efficiency
Electrostatic attraction fixes dry strength additives onto the surfaces of wood fibres in the wet end. The phenomenon of cationic starch retention occurs when positively charged starch molecules bind to the anionic cellulose. This prevents the soluble polymer from escaping during drainage.
System Charge Management
High levels of anionic trash or dissolved organic compounds in the white water can neutralize the cationic charge before it can interact with the wood fibres. This interference decreases cationic starch retention, leaving unattached starch in the water loop where it contributes to biological oxygen demand. Wet end monitoring tools track the zeta potential of the furnish to maintain an optimal charge balance.
When the system approaches charge neutrality, the binding of the starch reaches its maximum efficiency.
Performance Testing Method
Operators determine the efficiency of this chemical addition by measuring the starch concentration in the headbox and the white water. A high difference between these two points indicates successful cationic starch retention, whereas a narrow gap signals that the polymer is being washed out into the drain. These measurements allow mills to adjust the starch dosage or add charge control agents to restore the electrostatic balance.
If the addition rate exceeds the available anionic binding sites on the fibres, the excess starch remains suspended and degrades sheet properties.