A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Thermally and chemically modified wood-based panels
The modification of wood aims to alter the absorptive behaviour of wood and thus gives an advantage in terms of dimensional stability. The two main methods, of wood modification are chemical and thermal treatments; both result in an irreversible change of the wood cell components. The polyoses as main carrier of hydroxyl groups contribute most to moisture uptake and thus to the risk of dimensional changes. - The principle of a chemical modification is to replace the hydroxyl groups by a reagent; most study has undergone the substitution by acetyl groups referred to as acetylation of wood. Any chemical modification process results in a weight increase and keeps the wood in its swollen state. In contrast, thermal modification is always accompanied by a weight loss. The principle is to remove hydroxyl groups by thermal degradation thus leaving wood in its shrunken state. Wood modification has been subject to numerous studies and thermally modified solid wood became commercially viable whereas chemical modification processes often lack economical advantages due to high process and chemicals costs. - Increasingly, over recent years the focus is on applying those methods described on wood based panels as well. But despite promising results no commercial viability could be achieved yet. - The article gives an overview about different modification processes, their advantages but also negative impacts on board properties and highlights the limits in practical and economical terms.
Thermally and chemically modified wood-based panels
The modification of wood aims to alter the absorptive behaviour of wood and thus gives an advantage in terms of dimensional stability. The two main methods, of wood modification are chemical and thermal treatments; both result in an irreversible change of the wood cell components. The polyoses as main carrier of hydroxyl groups contribute most to moisture uptake and thus to the risk of dimensional changes. - The principle of a chemical modification is to replace the hydroxyl groups by a reagent; most study has undergone the substitution by acetyl groups referred to as acetylation of wood. Any chemical modification process results in a weight increase and keeps the wood in its swollen state. In contrast, thermal modification is always accompanied by a weight loss. The principle is to remove hydroxyl groups by thermal degradation thus leaving wood in its shrunken state. Wood modification has been subject to numerous studies and thermally modified solid wood became commercially viable whereas chemical modification processes often lack economical advantages due to high process and chemicals costs. - Increasingly, over recent years the focus is on applying those methods described on wood based panels as well. But despite promising results no commercial viability could be achieved yet. - The article gives an overview about different modification processes, their advantages but also negative impacts on board properties and highlights the limits in practical and economical terms.
Thermally and chemically modified wood-based panels
Paul, Wulf (author) / Ohlmeyer, Martin (author)
2010-01-01
Article/Chapter (Book)
Electronic Resource
English
DDC:
690
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