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Pihlak, Joel, 2021. Thermally modified hybrid aspen : adding value to fast growing broadleaved species in Northern Europe. Second cycle, A2E. Alnarp: SLU, Southern Swedish Forest Research Centre



This thesis is focused on thermal modification of hybrid aspen (Populus tremula L. x Populus
tremuloides Michx.), its mechanical properties, wood defects and potential use in construction.
In the recent years, wood as a building material has become increasingly popular. It is preferred
because of its aesthetic appeal; it is renewable and substitutes fossil-based energy consuming
materials. However, greater use of wooden products can also put more pressure on our natural
The main problems discussed in this paper were: mechanical characteristics after intense
thermal modification and overall quality characteristics of thermally modified hybrid aspen.
The present thesis conducts an empirical research of harvesting model trees, band sawing them
into boards and kiln-drying, in order to prepare samples for thermal modification. Specimens
were prepared for compressive strength, bending strength and wood density testing.
Mechanical tests were carried out following the standards of ISO 13061-17, ISO 13061-3 and
ISO 13061-2, accordingly. Furthermore, thermally treated sample boards from hybrid aspen
(Populus tremula L. x Populus tremuloides Michx.), were evaluated according to 14
predetermined quality characteristics.
Thermally modified hybrid aspen showed lower wood density and lower bending strength, but
higher compressive strength in comparison with untreated hybrid aspen material. Wood quality
evaluation showed that hybrid aspen had almost two times more wood defects compared to
European aspen. Thermal modification process had statistically insignificant effect on
measured wood quality.
As a result, it can be said, that despite the decrease of some mechanical properties, thermally
modified hybrid aspen still has a potential in areas where load bearing abilities are not so
important, for example sauna interiors and interior panelling.

Main title:Thermally modified hybrid aspen
Subtitle:adding value to fast growing broadleaved species in Northern Europe
Authors:Pihlak, Joel
Supervisor:Böhlenius, Henrik and Lutter, Reimo and Tullus, Hardi
Examiner:Agestam, Eric
Volume/Sequential designation:UNSPECIFIED
Year of Publication:2021
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:SM001 Euroforester - Master's Programme 120 HEC
Supervising department:(S) > Southern Swedish Forest Research Centre
Keywords:thermally modified wood, wood quality, short-rotation forestry, Hybrid aspen, European aspen, Populus tremula x tremuloides
Permanent URL:
Subject. Use of subject categories until 2023-04-30.:Forestry production
Deposited On:15 Dec 2021 09:18
Metadata Last Modified:16 Dec 2021 02:01

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