Comprehensive analysis of individual pulp fiber bonds quantifies the mechanisms of fiber bonding in paper

Abstract

The process of papermaking requires substantial amounts of energy and wood consumption, which contributes to larger environmental costs. In order to optimize the production of papermaking to suit its many applications in material science and engineering, a quantitative understanding of bonding forces between the individual pulp fibers is of importance. Here we show the first approach to quantify the bonding energies contributed by the individual bonding mechanisms. We calculated the impact of the following mechanisms necessary for paper formation: mechanical interlocking, interdiffusion, capillary bridges, hydrogen bonding, Van der Waals forces, and Coulomb forces on the bonding energy. Experimental results quantify the area in molecular contact necessary for bonding. Atomic force microscopy experiments derive the impact of mechanical interlocking. Capillary bridges also contribute to the bond. A model based on the crystal structure of cellulose leads to values for the chemical bonds. In contrast to general believe which favors hydrogen bonding Van der Waals bonds play the most important role according to our model. Comparison with experimentally derived bond energies support the presented model. This study characterizes bond formation between pulp fibers leading to insight that could be potentially used to optimize the papermaking process, while reducing energy and wood consumption.

Micro/Nano-fibrillated Cellulose from Cotton Linters as Strength Additive in Unbleached Kraft Paper: Experimental, Semi-empirical, and Mechanistic Studies

“…5% and 10% replacement of base pulp. The performance of the prepared handsheets was evaluated experimentally and compared with the predictions by semi-empirical models and mechanistic models (Hirn and Schennach 2015).…”

A Proposed Failure Mechanism for Pulp Fiber-Fiber Joints

“…In contrast, recent results show that there is a high degree of bonding between fiber surfaces (Persson et al 2013, Hirn and Schennach 2015. Therefore, we neglected possible flaws in the bonding for reasons of simplification.…”

Study of Hydraulic Properties of Uncoated Paper: Image Analysis and Pore-Scale Modeling

“…The cellulose material of the fibril is known to be strongly hydrophilic (see e.g. Hirn and Schennach 2015). So, the empty spaces between fibrils inside a bundle (about a few Nano meters) are expected to imbibe water strongly.…”

“…Based on their study, each cellulose fiber is composed of micro-fibril bundles (diameters of 20-30 nm). Hirn and Schennach (2015) found out that fibers in a paper bond to each other by six different mechanisms: interdiffusion, mechanical interlocking, capillary forces, Coulomb forces, hydrogen bonding, and van der Waals forces. They concluded that, in contrast to general belief that favors hydrogen bonding, van der Waals bonds play the most important role.…”