Paperboard Moisture Equilibration Rates under Cold Warehouse Storage
Cold warehouse paperboard equilibrates at rates four times slower than ambient standards, requiring staged thermal reconditioning to prevent moisture edge defects.
Stretch Film Permeability
Barrier Property
Rate of gas and moisture transmission through a stretched polymer wrap determines the atmospheric protection of palletized goods. In pallet wrapping, stretch film permeability dictates how much ambient humidity can penetrate the outer protective layer to reach the corrugated boxes inside. Lower permeability is preferred when shipping moisture-sensitive goods through tropical climates where damp air weakens the paperboard.
Diffusion Mechanism
Thinning of the film during the pre-stretch process increases the rate at which gas molecules pass through the polymer matrix. This rise in stretch film permeability occurs because the polymer chains align and thin out, reducing the path length for diffusing water vapour molecules. Packaging technicians measure this rate to select the optimum stretch ratio that ensures both load stability and barrier performance.
Storage Influence
Controlling this transmission rate is critical when pallets of dry food or paper products are stored in non-climate-controlled environments. High stretch film permeability allows condensation to form on the enclosed boxes during temperature fluctuations, leading to cardboard softening and column collapse. Specifying high-barrier films for these applications preserves the compression strength of the corrugated boxes, ensuring that the stacked pallet units remain upright and stable during prolonged storage, and reduces the need for expensive secondary wooden bracing on the transport vehicles.