Psychrometric Boundary Layer Analysis in Wrapped Paperboard Pallets during Transit
Polyethylene film wraps trap moisture desorbed by paperboard during thermal swings, elevating internal relative humidity and triggering mechanosorptive failure.
Containerboard Furnish
Fiber Composition
Raw material blends for corrugated packaging production consist of virgin softwood pulps, hardwood fibers and recycled paperboard stock mixed in water suspensions. Mill stock preparation processes define a containerboard furnish by adjusting the ratio of unbleached kraft pulp to old corrugated containers. This mixture determines the fundamental density, fiber length distribution and drainage characteristics of the paperboard sheet.
Structural Performance
Stock preparation plants refine raw fiber components to develop internal fibrillation and surface area before feeding the headbox. Incorporating high proportions of recycled fiber into a containerboard furnish introduces short, degraded fibers that reduce tensile energy absorption and compression resistance. Papermakers offset recycled strength losses by adding wet-end dry strength agents, refining softwood fractions separately, or adjusting multi-ply headbox layering.
Softwood kraft fibers form a strong structural matrix, whereas recycled fractions contribute bulk and cost control to the finished linerboard or fluting medium. Higher refining levels increase sheet density but reduce drainage speed on the paper machine wire, forcing reductions in production line speed.
Mill Yield
Contaminant loads from recycled stock require extensive screening and cleaning stages to prevent stock prep pump wear and sheet defects. Sticky residues, wax particles and plastics limit recycled content ratios in high-grade packaging applications.