Credit System Claims against the Fibre Actually inside the Box
Paperboard credit systems balance financial ledgers rather than physical fibers, requiring buyers to separate administrative certificates from batch fiber testing.
Pulping Mechanics
Definitional Principle
Physical principles govern the breakdown of wood or recycled paper into individual fibres suitable for papermaking. Understanding pulping mechanics involves analyzing the interaction between mechanical forces and the chemical bonds that hold the cellulose structure together. These forces are applied to separate the lignin from the fibres without damaging the cell walls.
Frictional Disintegration
In mechanical systems, the wood is pressed against a rotating grindstone or passed between metal discs. The pulping mechanics here rely on high shear and compression to peel the fibres apart and create a high yield pulp.
Chemical Interaction
In chemical pulping, the mechanics are different as the process uses heat and pressure to dissolve the lignin glue. This allows the fibres to be released with less mechanical effort, resulting in longer and stronger fibres for high quality grades. The efficiency of this process is measured by how well the system preserves the length and flexibility of the cellulose chains.
Proper management of these forces is necessary for creating a pulp that has the right drainage characteristics on the paper machine. It also impacts the energy consumption of the mill, as refining and defibering are among the most energy intensive steps in the entire production sequence.