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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Focus Session: Interactions Between Water and Cellulose II

CPP 37.1: Hauptvortrag

Donnerstag, 20. März 2025, 16:15–16:45, H34

Modelling Hygroexpansion of Compression and Opposite Wood of Conifer Branches: Bridging the Gap between Molecular and Cell Wall Level — Marie Hartwig-Nair, Sara Florisson, Kristofer Gamstedt, and •Malin Wohlert — Dep of Materials Science and Engineering, Uppsala University

Softwood branches develop compression wood (CW) in the lower and opposite wood (OW) in the upper part exhibiting different hygro-mechanical properties and differ in structure at several length scales. Distinctive differences are found at cell level, cell wall level and at the level of chemical composition of the lignin and hemicellulose matrix.

The effect each of these respective differences have on tissue level of wood hygromechanical properties is not yet clear. Here, a hierarchical multiscale modelling approach is employed, where the impact composition, MFA and lignin chemical difference have on wood hygro-expansion is studied by the means of hierarchical modelling as support to tissue level experimental investigation of CW and OW hygro-expansion [1]. With atomistic models and Molecular Dynamics simulations of lignin at different levels of hydration, swelling coefficients for the different lignin matrices are obtained [2] and implemented in a Finite Element (FE) model of the cell wall. The FE model also accounted for differences in MFA and composition.

The results of the FE model will be discussed and connected to the MD and tissue level results.

[1] M. Hartwig-Nair et al., Wood Sci. Technol., 2024, 58, 887-906.

[2] M. Hartwig-Nair et al., Wood Sci. Technol., 2024, in press.

Keywords: Multiscale modelling; Molecular modelling; Wood hygromechanics; Moisture interaction with cell wall polymers