Fundamental aspects

Electrocapillary phenomena

Amir Akbari, Majid Soleimani, Reghan Hill, and Theo van de Ven

Improving the properties of fibre-based products (e.g., mechanical and barrier) hinges on the controllability of fibre conformational changes during pulping processes. Understanding the underlying mechanisms of wood-water interactions at various drying stages provides new practical and economical strategies to achieve open and collapsed fibres for desired applications. Here, we study idealized representative structures of wood-fibres through first-principle calculations to simulate drying and determine the conditions leading to open and collapsed conformations. 

Wood-fibre configuration significantly affects various paper properties, such as strength, hygroscopicity, and resistance to curling and edge crush. We are investigating the effect of capillary forces on fibre conformation. First, we calculated bubble and drop shapes on a curved surface, finding that bubbles and drops move to the most inwardly curved regions of a surface. Modelling wood fibres using a circular tube, we examined the cross-sectional deformation of wood fibres caused by capillary forces during drying, seeking necessary conditions for complete lumen collapse. Finally, we are analysing longitudinal fibre deformation driven by interfaces at fibre crossings in fibre networks. Together, these investigations help to understand the role of capillary forces on the fibre configuration as the moisture content changes


Cellulose crystal structures

Kevin Conley, Louis Godbout, M.A. (Tony) Whitehead and Theo van de Ven

We study the distortions of the crystalline structure of cellulose using molecular modelling and experimental techniques. Flat crystals relax into twisted rods with surprising implications to cellulosic materials. Can these effects at the atomistic level predict macroscopic behavior?

Cellulose crystal structures

Fibril twist at the micrometer length scale (cellulose, 1994, 4, 209-220)
Twist in tree trunk at the m scale (Picture seen in P&P. McGill)
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