Chemical and ultrastructural changes of ash wood thermally modified using the thermo-vacuum process: I. Histo/cytochemical studies on changes in the structure and lignin chemistry
Abstract
Changes in structure and lignin chemistry were investigated in ash wood thermally modified (TMW) by the thermo-vacuum (Termovuoto) process for 3 h at 190–220°C by means of light, fluorescence, and transmission electron (TEM) microscopy combined with histo/cytochemistry. Variation in changes in native cell color in TMWs was positively correlated with differences in lignin content between cell types and cell wall regions in the reference wood. Histochemical staining showed increasing amounts of acidic groups in TMWs with different response to ethanol extraction between secondary cell walls and CMLcc (compound middle lamella/middle lamella cell corner) regions. Fluorescence microscopy of TMWs and references showed a difference in intensity and color emission of lignin autofluorescence, reflecting modification of lignin in TMWs. Changes in histochemistry and fluorescence were prominent at and above 200°C. With TEM, increased intensity of lignin staining and distortion of fiber S1 layers were detected in TMW treated for 3 h at 220°C (TMW3 h, 220°C). TMW3 h, 220°C differed significantly in molecular ultrastructure of fiber cell walls compared to references, such as loss of the lamellar structure and size and distribution of lignin aggregates. The modification in CMLcc structure in ash TMW3 h, 220°C is different from that of softwoods.
Acknowledgments
The authors gratefully acknowledge funding provided by Formas projects 2009-582 and 2011-416 and the Eco-Innovation initiative-EU project TV4NEWOOD Eco/12/333079.
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©2015 by De Gruyter
Articles in the same Issue
- Frontmatter
- Original Articles
- Study on the residual lignin in Eucalyptus globulus sulphite pulp
- Hydrogenolysis of lignin in ZnCl2 and KCl as an inorganic molten salt medium
- Synthesis of lignin polyols via oxyalkylation with propylene carbonate
- Preparation of water-dispersive poly(3,4-ethylenedioxythiophene) (PEDOT) conductive nanoparticles in lignosulfonic acid solution
- Properties of polyurethane (PUR) films prepared from liquefied wood (LW) and ethylene glycol (EG)
- Dynamic response of earlywood and latewood within annual growth ring structure of Scots pine subjected to changing relative humidity
- One-stage thermo-hydro treatment (THT) of hardwoods: an analysis of form stability after five soaking-drying cycles
- The variation of tangential rheological properties caused by shrinkage anisotropy and moisture content gradient in white birch disks
- Inheritance of basic density and microfibril angle and their variations among full-sib families and their parental clones in Picea glehnii
- Mechanical properties and chemical composition of beech wood exposed for 30 and 120 days to white-rot fungi
- Chemical improvement of surfaces. Part 3: Covalent modification of Scots pine sapwood with substituted benzoates providing resistance to Aureobasidium pullulans staining fungi
- Chemical and ultrastructural changes of ash wood thermally modified using the thermo-vacuum process: I. Histo/cytochemical studies on changes in the structure and lignin chemistry
- Chemical and ultrastructural changes of ash wood thermally modified (TMW) using the thermo-vacuum process: II. Immunocytochemical study of the distribution of noncellulosic polysaccharides
- Revisiting hardboard properties from the fiber sorting point of view
- Effects of acetylation and formalization on the dynamic water vapor sorption behavior of wood
- Immune-regulatory activity of methanolic extract of Acacia confusa heartwood and melanoxetin isolated from the extract
- Stereomicroscopic optical method for the assessment of load transfer patterns across the wood-adhesive bond interphase
Articles in the same Issue
- Frontmatter
- Original Articles
- Study on the residual lignin in Eucalyptus globulus sulphite pulp
- Hydrogenolysis of lignin in ZnCl2 and KCl as an inorganic molten salt medium
- Synthesis of lignin polyols via oxyalkylation with propylene carbonate
- Preparation of water-dispersive poly(3,4-ethylenedioxythiophene) (PEDOT) conductive nanoparticles in lignosulfonic acid solution
- Properties of polyurethane (PUR) films prepared from liquefied wood (LW) and ethylene glycol (EG)
- Dynamic response of earlywood and latewood within annual growth ring structure of Scots pine subjected to changing relative humidity
- One-stage thermo-hydro treatment (THT) of hardwoods: an analysis of form stability after five soaking-drying cycles
- The variation of tangential rheological properties caused by shrinkage anisotropy and moisture content gradient in white birch disks
- Inheritance of basic density and microfibril angle and their variations among full-sib families and their parental clones in Picea glehnii
- Mechanical properties and chemical composition of beech wood exposed for 30 and 120 days to white-rot fungi
- Chemical improvement of surfaces. Part 3: Covalent modification of Scots pine sapwood with substituted benzoates providing resistance to Aureobasidium pullulans staining fungi
- Chemical and ultrastructural changes of ash wood thermally modified using the thermo-vacuum process: I. Histo/cytochemical studies on changes in the structure and lignin chemistry
- Chemical and ultrastructural changes of ash wood thermally modified (TMW) using the thermo-vacuum process: II. Immunocytochemical study of the distribution of noncellulosic polysaccharides
- Revisiting hardboard properties from the fiber sorting point of view
- Effects of acetylation and formalization on the dynamic water vapor sorption behavior of wood
- Immune-regulatory activity of methanolic extract of Acacia confusa heartwood and melanoxetin isolated from the extract
- Stereomicroscopic optical method for the assessment of load transfer patterns across the wood-adhesive bond interphase