Similarities in bonding influence between pre-failure tensile creep and stress–strain behavior of paper

The role of bonding in the pre-failure tensile creep behavior of paper was analyzed using handsheets with a range of bonding levels produced through manipulation of relative bonded area and specific bond strength. This was done by varying the level of wet pressing (to change relative bonded area) and using debonding and bonding agents (to change specific bond strength). Once manufactured, sheets underwent an extensive battery of creep testing. Creep testing was conducted under constant humidity and cyclic humidity (accelerated creep) conditions. Microscopic analysis techniques were also employed to visually study bonded area loss from creep strain. Overall, the results from this study show that the role of bonding in tensile creep behavior (and accelerated creep behavior) is no different than its role in stress–strain behavior. The findings show that bonding influences tensile creep behavior by altering sheet efficiency and how effectively stress is distributed within the structure, bonded area loss is a strain-induced phenomenon and bonding is not the cause of accelerated creep behavior.