Quality control of thermally modified timber using dynamic vapor sorption (DVS) analysis

Humar, Miha (author), Repič, Rožle (author), Kržišnik, Davor (author), Lesar, Boštjan (author), Cerc Korošec, Romana (author), Brischke, Christian (author), Emmerich, Lukas (author), Rep, Gregor (author)

The importance of thermal modification is increasing worldwide. Increased use of thermally modified timber (TMT) has resulted in a need for reliable quality control, comprising control of variation of the production within defined limits, allowing third-party control in the case of certification and the regulation of customer complaints and claims. Techniques are thus needed to characterise the modification of quality in terms of improved target properties of TMT during industrial production, and of TMT products that have been in service for an arbitrary time. In this study, we aimed to utilise dynamic vapor sorption (DVS) for this purpose. Norway spruce (Picea abies) and European beech (Fagus sylvatica) samples were thermally modified at different temperatures according to different heat treatment techniques: (1) the Silvapro process based on an initial vacuum; (2) an air heat treatment, whereby samples were wrapped in aluminium foil; (3) thermal modification of wood samples in the ambient atmosphere in a laboratory oven. Wood samples from closed processes were analysed for validation. TMT was characterised with respect to mass loss, colour and density. Mass loss of wood due to modification (ML$_{TM}$) was correlated with factors derived from DVS analysis. The present DVS measurements suggest that the equilibrium wood moisture content (EMC$_{95\%}$ $_{RH}$), the time to reach 10% wood moisture content (t$_{10\%}$ $_{MC}$), and the elongation factor, c, derived from a logarithmic function, can serve as alternative parameters to characterise the quality of several thermal modification processes. Further studies are recommended using other wood species, different modification processes and further parameters gained from DVS measurements to understand the robustness and the predictive power of the applied technique.

• Language: English
• Keywords: thermal modification, quality control, dynamic vapour sorption, wood, moisture content
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty; FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2020
• Number of pages: 12 str.
• Numbering: Vol. 11, iss. 6, art. 666
• PID: 20.500.12556/RUL-133934
• UDC: 630*8
• ISSN on article: 1999-4907
• DOI: 10.3390/f11060666
• COBISS.SI-ID: 19360259
• Publication date in RUL: 20.12.2021

Record is a part of a journal

• Title: Forests
• Shortened title: Forests
• Publisher: MDPI
• ISSN: 1999-4907
• COBISS.SI-ID: 3872166

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 11.06.2020

Secondary language

• Language: Slovenian
• Keywords: termična modifikacija, kontrola kakovosti, dinamična sorpcija vodne pare, les, vlažnost lesa