Interfibrillar Swelling Stress Redistribution Analysis for Coated Recycled Fiber Boards
Interfibrillar swelling in recycled board plies generates interface shear stresses that fracture coatings and degrade stacking strength under cyclic humidity.
ISO 8226
Standardized Measurement
Testing procedures for determining the dimensional changes of paper when exposed to varying relative humidity are specified by international agreements. The methodology defined in iso 8226 outlines how to measure the hygroinstability of paper and board under controlled environmental transitions. It provides a reliable framework for assessing how much a sheet expands or contracts as it absorbs or releases moisture.
Hygroinstability Evaluation
Hygroinstability evaluation requires precise conditioning chambers where relative humidity can be altered while maintaining a constant temperature. Under the protocols of iso 8226, specimen strips are subjected to specified humidity levels, and their length changes are measured with high-precision instruments. This testing is crucial for printing papers where misregistration must be avoided.
Operational Tolerance
Operational tolerance in multicolor offset printing is directly influenced by the hygroinstability of the paper stock. If the paper exhibits high expansion values during the run, successive color layers will not align properly, resulting in blurry images and rejected batches. Packaging converters use iso 8226 values to select papers that will remain flat and stable during subsequent coating and laminating processes.
By verifying that the paper complies with the specified expansion limits, mills can guarantee trouble-free feeding on high speed presses. Printers rely on this standard to resolve disputes regarding stock that exhibits excessive curling or waving in the pressroom.