Review: The Creep Response of Paper

Abstract

This article examines the literature pertaining to the creep behavior of paper. The basic concept of creep, the terminology used to describe creep, and the various ways to present creep are introduced. This is followed by a historical overview of creep in paper. Using this framework, discussions centered on tensile, compressive, and accelerated creep are presented. For years,
research efforts have focused on accelerated creep. Because of this diversion, an acknowledged fundamental understanding of paper creep is lacking. Using previous data for tensile creep in constant humidity conditions, a rudimentary model of creep in paper is developed. The model clearly demonstrates that the role of bonding is accounted for simply with an efficiency factor that acts to magnify the stress. In addition to the impact of inter-fiber changes, intra-fiber effects resulting from hardening and wet-straining are demonstrated. It is suggested that compressive creep differs from tensile creep due to material instability. Accelerated creep is taken to be the result of moisture-induced load cycling. The result of this discourse is that to increase understanding, fundamental studies of creep behavior in constant conditions are and will be more fruitful than studies in cyclic humidity.