Effects of Drying on the Mechanical Properties of Paper and their Relationship to the Treatment Of Paper

Abstract

ABSTRACTThe effects of drying on paper after water immersion are explored by evaluating mechanical properties. When paper is wet, structural interfiber hydrogen bonds are disrupted; drying reverses this process. However, some “as manufactured” mechanical properties are lost after wetting and drying. The method of drying was found to be critical for regaining the mechanical properties of a dried sheet.The effects of (1) wet-pressing (weight on paper during drying) and (2) wet-straining during drying are assessed. Application of incremental increases of the two variables results in changes of the mechanical properties which eventally reach and exceed the original mechanical properties which are lost during standard water immersion and drying treatments.The treatment method which most closely reproduces the “as manufactured” properties involves wet-pressing and wet-stretching. In particular, friction stretch-drying in an air-bag press can approximate original drying conditions. However, alterations of optical properties of the paper and design media due to elevated pressure prevents endorsement of the methodology.