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Doctoral thesis, 2021

The biology and properties of wood for nanocellulose production

Bünder, Anne

Abstract

Wood is a renewable and environmentally friendly raw material envisioned for the production of novel materials. In this interdisciplinary thesis project, I investigated genetic factors controlling cellulose biosynthesis, cellulose microfibril dimensions, wood mechanical properties and factors that influence nanocellulose extraction from wood.  
I show that RNA-interference-mediated reduction of the CELLULOSE SYNTHASE-INTERACTIVE 1 (CSI1), which is known to link the cellulose synthase complex (CSC) to cortical microtubules (cMTs), affects wood mechanical properties as well as fibre dimensions and cellulose degree of polymerization (DP) in hybrid aspen (Populus tremula x tremuloides).  
Furthermore, the reduced level of CSI1 was shown to negatively affect cellulose nanofibril (CNF) separation, possibly due to structural differences in cellulose microfibrils (CMFs) and/or cell wall matrix interactions. Additionally, alteration in cellulose DP and wood mechanical properties were found to be preserved in the manufactured CNF networks. 
In collaboration with material scientists, I also investigated the effect of tension wood and variations in wood lignin content on nanocellulose isolation and properties. We found that the cell wall structure and composition of the tension wood, negatively affect CNF isolation when using TEMPO-mediated oxidation followed by mechanical nanofibrillation. Unexpectedly, high wood lignin content facilitated CNF isolation, potentially through increased cell wall porosity caused by TEMPO-mediated delignification. Taken together, the results show that native wood properties affect CNF isolation as well as CNF properties and motivate for further genetic improvement of trees and wood as a raw material for nanocellulose production.

Keywords

CELULOSE SYNTHASE-INTERACTING1 (CSI1); Cellulose microfibrils (CMFs); Secondary cell wall (SCW); Wood mechanical properties; Degree of polymerization (DP); Nanocellulose; Cellulose nanofibrils (CNFs); TEMPO-oxidation; Populus

Published in

Acta Universitatis Agriculturae Sueciae
2021, number: 2021:73
ISBN: 978-91-7760-823-3, eISBN: 978-91-7760-824-0
Publisher: Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences

Authors' information

Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology

UKÄ Subject classification

Wood Science

URI (permanent link to this page)

https://res.slu.se/id/publ/113856