Magnetic resonance imaging of water vapor absorption in simulated corrugated board

Water vapor absorption into a multi-layer simulated corrugated board structure was investigated using magnetic resonance imaging (MRI). Humidity and other ambient conditions considerably affect the strength and durability of corrugated board, and through creep, collapse of the corrugated board structures at unexpectedly low load levels. Currently, water vapor permeation and absorption are investigated with methods that do not elucidate the behavior of individual sheet layers in corrugated board. With MRI, signal intensity changes caused by water absorption can be spatially located and identified, providing a promising tool for the assessment of internal changes in a board, and its interaction with humidity. In this work, simulated corrugated board assemblies, consisting of alternating straight layers of linerboard and fluting material, were constructed, subjected to one-sided high humidity environment and periodically MR imaged to obtain temporal information on water accumulation at high relative humidity. It was observed that, in general, the fluting layers would exhibit higher signal intensities sooner, and by extension, higher water accumulation, when compared to the linerboards. The presented study provides insight into the behavior of paperboards in a double-wall corrugated board structure while under constant high humidity. In the future, actual corrugated board samples could be investigated in periodically fluctuating relative humidity and under constant stress to obtain information on the mechanosorptive creep.