The Academy Lecture

THE WOOD FIBRE STRUCTURE - HOW TO BE UTILISED?

Lennart SALMÉN

Innventia, Stockholm, Sweden
(lennart.salmen@innventia.com)

Abstract

There is increasing demand for utilizing wood as a replacement for products derived from fossil fuels, both in the energy sector and as a replacement for various kinds of materials. In converting the wood into such products in an economically feasible way, new routes have to be explored to a better understanding of the wood ultra-structure. This applies especially to the interaction between the wood constituents in the cell wall in order to be able to separately extract these at high purity. In this paper some features of the polymer arrangement in this structure will be discussed, with a focus on the impact of the possibility of separating the wood components, specifically cellulose, lignin, and the hemicelluloses xylan and glucomannan. It is clearly evident that the secondary cell wall of wood fibres is a highly intermixed composite material for which the very detailed structure is not yet fully understood. Bonds between lignin and the hemicelluloses are clearly a fact that will adversely affect the ability for disintegration and more so after pulping when the degree of such bonds may have increased. The most important factor affecting the separation of the major component, the cellulose, is the fact that increased aggregation has to be avoided. In doing so, new pulping processes have to be adapted, with the principle of extracting lignin and hemicelluloses at lower temperatures in order to inhibit the self-organizing tendency of the cellulose. However, such an extraction also has to take into account of ways to stabilise the structure with spacers in between cellulose microfibrils to facilitate further processing without later aggregation.

The Lecturer

Prof. Lennart Salmén is currently Deputy Director for the business area Biorefining at Innventia, former STFI-Packforsk, in Stockholm, Sweden.
Salmén was born 1951 and was educated at KTH, the Royal Institute of Technology, in Stockholm where he received his PhD in 1982 in Paper Technology on the subject of “Temperature and Water Induced Softening Behaviour of Wood Fibre based Materials”.
Apart from a Research Fellowship at PAPRICAN, Montreal, Canada in 1978-1979 Salmén has been employed with Innventia (STFI, The Swedish Pulp and Paper Research Institute), in various positions since 1975.
Salmén was appointed Docent, Associate Professor, in Paper Technology at KTH, Stockholm in 1987. He has since then been qualified for Professorships in the areas of Wood Technology, Fibre Science, Paper Technology and Mechanical Pulping and was appointed adj. Professor at the Mid Sweden University in 2012.
The research interests of Salmén has mainly been devoted to the understanding of the relationship between the properties of the wood polymeric constituents and the macroscopic physical properties of fibres, wood and paper materials exploring new and innovative techniques for enhancing the understanding. Studies of softening phenomena, cell wall properties, micro-mechanical modelling, water interaction, mechano-sorptive creep, dimensional stability, fatigue of wood and mechanical and chemi-mechanical pulping are among the areas of published work. Much of the work has been devoted to the interaction of the cellulosic material with moisture where especially Salmén's development of moisture induced dynamic FTIR has been shown to give new insights. In all these research areas Salmén has been the supervisor of a number of PhD students. Salmén is the author of more than 180 reviewed scientific papers in the field of fibre, wood and paper physics and the Editor of 5 books.
During the years of 1993 to 1995 Salmén served as secretary, vice chairman and lastly Chairman of the Tappi Paper Physics Committee which involved the responsibility of organizing of a number of research conferences.
In the area of Wood Science Salmén has been highly involved in Wood Mechanics within COST EU-actions trying to bridge the knowledge between the sciences of wood and paper technology. This engagement lead up to the formation of the European Society of Wood Mechanics, ESWM, in 2000 for which Salmén served as vice chairman.
In 1996 Salmén was elected Fellow of IAWS, the International Academy of Wood Science, for which he in 2011 he became the president of.

The Lecture was presented during the 2012 IUFRO Conference Division 5 / Forest Products meeting in Estoril / Portugal

The wood fibre structure - how to be utilised?