Experimental Method Development for MRI Moisture Measurements in Paper Materials

Sammanfattning

An understanding of moisture transport within sized paperboards is an important quality aspect for the packaging industry. In this study, the experimental technique of magnetic resonance imaging (MRI) is used to develop a testing methodology which can measure, characterise and quantify the transport of water within paper materials. A methodology for in-plane liquid uptake measurements within the MRI was developed and found to be applicable for hydrophilic materials. Through thickness testing was performed in the MRI and 1-D profiles were obtained along the throughthickness direction of the paper materials with a spatial resolution of 31μm and a temporal resolution of 2 minutes measurement acquisition time. To give further insight into the mechanisms of liquid transport within the fibre structure of the paper materials apparent diffusion coefficients were estimated and found to be on the order of 10−12 m2/s which strongly suggest that the rate defining mechanism for hydrophobized paper is moisture diffusion within the fibers. This study also explores the various issues encountered during method development and lays a foundation for further work.