Elemental composition of wood as a potential marker to evaluate heat treatment intensity

185

Key message An efficient use of thermal treatment of wood requires a depth understanding of the chemical modifications induced. This is a prerequisite to avoid problems of process control, and to provide high quality treated wood with accurately assessed properties to the market. Properties and structural anatomy of thermally modified woods are slightly different than un-processed woods from a same wood species. So it is necessary to create or adapt new analytical methods to control their quality. Context Heat treatment as a wood modification process is based on chemical degradation of wood polymer by heat transfer. It improves mainly the resistance of wood to decay and provides dimensional stability. These improvements, which come at the expense of a weakening of mechanical properties, have been extensively studied. Since a decade, researches focused mainly on the understanding of wood thermal degradation, on modelling, on quality prediction and quality control. Aims We aimed at reviewing the recent advances about (i) the analytical methods used to control thermal treatment; (ii) the effects on wood decay resistance and (iii) the advantages and drawbacks of a potential industrial use of wood heating. Methods We carried out a literature review of the main industrial methods used to evaluate the conferred wood properties, by thermal treatment. We used papers and reports published between 1970 and 2015, identified in the web of science data base.. Results Approximately 100 papers mostly published after 2000 were retrieved. They concentrated on: (i) wood mass loss due to thermal degradation determination, (ii) spectroscopic analyses of wood properties, (iii) colour measurements, (iv) chemical composition, (v) non-destructive mechanical assessments and (vi) use of industrial data. Conclusions One of most interesting property of heat-treated wood remains its decay resistance. Durability test with modified wood in laboratory are expensive and time-consuming. This review displays data from different analytical methods, such as spectroscopy, thermogravimetry, chemical analyses or mechanical tests that have the potential to be valuable indicators to assess the durability of heat treated wood at industrial scale. However, each method has its limits and drawbacks, such as the required investment for the equipment, reliability and accuracy of the results and ease of use at industrial scale.

Section: Durability Prediction By Elemental Composition (O/c) Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Control of wood thermal treatment and its effects on decay resistance: a review

Candelier

Thévenon

Pétrissans

et al. 2016

185

“…The influence of treatment conditions on chemical composition and conferred properties of thermally modified wood have been intensively investigated. Previous studies have shown that new properties conferred to thermally modified wood are directly related to thermal treatment intensity, which depends directly on duration and treatment temperature (Nguila Inari et al 2009;Šušteršic et al 2010). These findings have resulted in the development of a quality control marker for thermally modified wood based on mass loss (ML).…”

Section: Introductionmentioning

confidence: 99%

Variations in the natural density of European oak wood affect thermal degradation during thermal modification

Hamada

Pétrissans

Mothe

et al. 2015

Self Cite

“…Heat-treated wood at 280°C becomes totally resistant to decay, but its mechanical properties are strongly affected. Resistance to decay depends of the temperature and duration of treatment Nguila Inari et al 2009;Šušteršic et al 2010). Chemical modifications occurring during treatment are believed to be at the origin of durability improvement.…”

mentioning

confidence: 99%

New alternatives for wood preservation based on thermal and chemical modification of wood— a review

Gérardin

2015

Self Cite

193

126

Key message Increasing environmental pressures appearing over the last few years have led to important changes in the field of wood protection. In this context, new technologies, based either on thermal or chemical modifications, suggest increasing interest in prospect of programmed ban of biocide products.• Context The evolution of the regulations on the use of biocide products has led to important changes in the field of wood preservation, leading to an increasing interest for non-biocide treatments like thermal or chemical modifications to face to the programmed ban of biocide products.• Aims The paper reviews the different non-biocide alternatives developed currently on an industrial scale, highlighting their main characteristics and applications.• Results Different treatments have been developed on an industrial scale involving mainly thermal modifications and acetylation, furfurylation and DMDHEU constituting already available solutions.• Conclusion Different non-biocide alternatives already exist and will become more important in the next decades due to the increasing legislative pressure driven by environmental considerations.