Fibre Integrity
Fibre loss during multiple recycling loops determines the functional lifespan of paper substrates. Secondary furnish degradation occurs when individual cellulose chains break down under mechanical shear during stock preparation and refining. This process shortens the average length of the suspended fibres, which reduces the bonding sites available for sheet formation.
Longer fibres provide the structural matrix for high strength packaging, while shorter fragments limit the ability of the material to resist tensile forces.
Refining Efficiency
Consistency in wet end chemistry helps mitigate the impact of recycled stock processing on sheet properties. Mill operators monitor freeness values to adjust the degree of mechanical work applied to the pulp slurry. Excessive refining causes further breakdown of the secondary furnish, which increases the population of fines and compromises drainage on the wire section.
High concentrations of these fine particles hinder the development of physical paper characteristics. Precise control over the energy input remains necessary to maintain the balance between strength and formation uniformity.
Mechanical Impact
Physical attrition during the pulping stage breaks down the internal structure of post-consumer fibre components. Stiff, hornified fibres often result from repeated drying and wetting cycles inherent in circular paper loops. This physical transformation permanently alters the capacity of the fibre to hydrogen bond during the subsequent papermaking process.
Consequently, the addition of virgin long-fibre reinforcement compensates for the structural deficit observed in older recycled furnishes. High rates of secondary furnish degradation necessitate structural adjustments in the paper machine approach flow to sustain consistent sheet quality.
