A correlation between the gas and liquid permeabilities of beech wood heat-treated in hot water and steam mediums

Hamid Reza Taghiyari,Aisona Talaei,Ali Karimi

doi:10.4067/s0718-221x2011000300008

Hamid Reza Taghiyari, Aisona Talaei + Show 1 more

Open Access

https://doi.org/10.4067/s0718-221x2011000300008

Copy DOI

Abstract

Heat-treatment, a major method of wood modification for improving dimensional stability and natural durability, has been studied considerably in the scientific literature. This study will focus on the effect of heat-treatment on permeability, an important physical property of wood by subjecting beech samples to two different mediums of hot water and steam, as well as in two buffered hot water of pH 7 and 8. Hydrothermal treatment caused gas permeability to decrease to its lowest value among the treatments (91.6% decrease comparing the control treatment). Hydrothermal treatment in buffered hot water of pH 8 made the lowest impact on gas permeability (12.3% decrease). The decrease in gas permeability was due to settlement of extractives on vessel perforation plates. Gas permeability showed a highly significant correlation with the amount of swelling in radial direction. Low correlation was found between liquid permeability with water absorption and the amount of swelling. Gas permeability is considered a suitable criterion for predicting the amount of swelling in beech wood.

Highlights

Of all the various wood modification processes that have been studied, thermal modification is by far the most commercially-advanced
Hydrothermal heat-treatment resulted in gas permeability decreasing to its lowest value of 1.1 ×10-13 m3 m-1 (91.6% decrease)
Buffered hot water of pH7 resulted in the mitigation of the decreasing effect of hydrothermal treatment, still gas permeability value was quite low (3.7 ×10-13 m3 m-1)

Summary

Introduction

Of all the various wood modification processes that have been studied, thermal modification is by far the most commercially-advanced It has long been recognized as a potentially useful method to improve the dimensional stabilization of wood and increase its decay resistance (Hill 2006). Tiemann (1915) was one of the first researchers to report on the effect of high-temperature treatment upon the physical properties of wood. He heated air-dried wood in superheated steam at 150°C for 4 hours, which reduced the subsequent moisture sorption by 10-25%, with relatively low reductions in strength found in most cases. What is less certain is the exact points at which the different reactions become dominant (Stamm et al 1946)

Results

Discussion

Conclusion