WOOD RESEARCH Volume 62, Number 5, 2017
Zhe Wang, Bailing Sun, and Junliang Liu

Investigation of volatile products released during vacuum heat treatment of larch wood

The aim of this study was to investigate the components of volatile by-products released at different treatment temperatures. For this objective, the aldehydes and ketone were trapped in DNPH solution and the aldehyde and ketone derivatives were analyzed by HPLC. The acids and alcohols were trapped in deionized water and analyzed by HPLC and GC. The other volatile organic compounds were trapped on Tenax TA tubes and analyzed by GC-MS. The results showed that there was an increasing trend in the concentrations of aldehydes, acids, and alcohols with the increasing treatment temperature. The heat treatment at higher temperature resulted in more kinds of volatile organic compounds.

WOOD RESEARCH Volume 63, Number 6, 2018
Jiajun Wang, Junliang Liu, Lin Ni, and Jianzhang Li

Thermopressed binderless fiberboards from wheat straw by adding black liquor

For the shortage of timber resources and the sake of the formaldehyde emissions, people desire to use non-adhesive bonding technology. This paper studies the chemical composites of black liquor, at different contents ranging from 20 to 40 wt%, into fiberboards made from wheat straw pulp. Adding a little black liquor has positive effect on qualities of boards, contributing to presence of proteins and lignin in black liquor, but adding too much liquor would decrease properties of them for the ash content. The FT-IR measurements indicated that there are more low-molecular substance and hydrogen bonds producing after fining and thermopressing processes. The thermo analysis were conducted to better understand these results. The physical and mechanical properties of the resulting fiberboard were evaluated. The results showed that binderless fiberboards by adding 30 wt% have good mechanical and water resistance properties which can partly satisfy the requirements of the relevant standards specifications.

WOOD RESEARCH Volume 64, Number 5, 2019
Bailing Sun, Yubo Chai, Junliang Liu, and Holger Militz

Acetylation of plantation softwood without catalysts or solvents

This study explored acetylation of wood of Larix kaempferi (Lamb.) Carr. and Pinus sylvestris var. mongolica Litv. without catalysts or solvents. Both wood samples were impregnated with acetic anhydride and subsequently heated to 120°C for different reaction durations (0.5-8 h) in the esterification reagent. The extent of acetylation was measured by weight percent gain (WPG), which varied from 12.0% to 21.7% and 13.6% to 22.3% for both wood species. The cell wall bulking and anti-shrink efficiency (ASE) started to increase faster and then increase slower with increasing reaction time. As the WPG reached 19.2% and 17.8% or more separately, ASE of both acetylated wood were above 50% in any RH conditions. FTIR, CP/MAS 13C NMR, and XPS studies produced evidences for acetylation of both wood species. The degree of acetylation of wood cell wall polymers increased with increasing WPG, but during the process degradation of lignin and acid hydrolysis of carbohydrates occurred.

WOOD RESEARCH Volume 64, Number 1, 2019
Bailing Sun, Zhe Wang, and Junliang Liu

Study on color and surface chemical properties of Eucalyptus pellita wood subjected to thermo-vacuum treatment

The objective of this study was to investigate the color and surface chemical properties of Eucalyptus pellita wood subjected to thermo-vacuum treatment. Specimens were thermally modified in a vacuum at various temperatures for 4 h. The color parameters of untreated and heattreated samples were measured using the CIE Lab method. Surface chemical properties were evaluated by UV-Vis spectroscopy, 13C NMR spectroscopy and X-ray photoelectron spectroscopy. The results showed that eucalypt wood became darker uniformly throughout with the increase of treatment temperature, and the total color variation ΔE* obviously increased at higher temperature. The spectral changes indicated that degradation and oxidation of hemicellulose, lignin and extractives contributed to the formation of color substances during thermo-vacuum treatment. Crystalline content of carbohydrates increased. The decrease in O/C ratio signified the increase of the relative content of lignin and extractives on the wood surfaces in the heating process.