scholarly journals Characterisation of Moisture in Scots Pine (Pinus sylvestris L.) Sapwood Modified with Maleic Anhydride and Sodium Hypophosphite

Forests ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1333
Author(s):  
Injeong Kim ◽  
Emil Engelund Thybring ◽  
Olov Karlsson ◽  
Dennis Jones ◽  
George I. Mantanis ◽  
...  
Keyword(s):  
Cell Wall ◽  
Maleic Anhydride ◽  
Scots Pine ◽  
Cell Walls ◽  
Sodium Hypophosphite ◽  
Hydroxyl Groups ◽  
Capillary Water ◽  
Saturated State ◽  
Water Saturated ◽  
Modified Wood

In this study, the wood–water interactions in Scots pine sapwood modified with maleic anhydride (MA) and sodium hypophosphite (SHP) was studied in the water-saturated state. The water in wood was studied with low field nuclear magnetic resonance (LFNMR) and the hydrophilicity of cell walls was studied by infrared spectroscopy after deuteration using liquid D2O. The results of LFNMR showed that the spin–spin relaxation (T2) time of cell wall water decreased by modification, while T2 of capillary water increased. Furthermore, the moisture content and the amount of water in cell walls of modified wood were lower than for unmodified samples at the water-saturated state. Although the amount of accessible hydroxyl groups in modified wood did not show any significant difference compared with unmodified wood, the increase in T2 of capillary water indicates a decreased affinity of the wood cell wall to water. However, for the cell wall water, the physical confinement within the cell walls seemed to overrule the weaker wood–water interactions.

scholarly journals Mode of action of brown rot decay resistance in modified wood: a review

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 239-246 ◽  
Author(s):  
Rebecka Ringman ◽  
Annica Pilgård ◽  
Christian Brischke ◽  
Klaus Richter
Keyword(s):  
Cell Wall ◽  
Mode Of Action ◽  
Wood Decay ◽  
Brown Rot ◽  
Decay Resistance ◽  
Hydroxyl Groups ◽  
Decay Fungi ◽  
Brown Rot Decay ◽  
Thermally Modified Wood ◽  
Modified Wood

Abstract Chemically or physically modified wood materials have enhanced resistance to wood decay fungi. In contrast to treatments with traditional wood preservatives, where the resistance is caused mainly by the toxicity of the chemicals added, little is known about the mode of action of nontoxic wood modification methods. This study reviews established theories related to resistance in acetylated, furfurylated, dimethylol dihydroxyethyleneurea-treated, and thermally modified wood. The main conclusion is that only one theory provides a consistent explanation for the initial inhibition of brown rot degradation in modified wood, that is, moisture exclusion via the reduction of cell wall voids. Other proposed mechanisms, such as enzyme nonrecognition, micropore blocking, and reducing the number of free hydroxyl groups, may reduce the degradation rate when cell wall water uptake is no longer impeded.

scholarly journals Effects of Changes in Biopolymer Composition on Moisture in Acetylated Wood

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 719
Author(s):  
Tiantian Yang ◽  
Emil Engelund Thybring ◽  
Maria Fredriksson ◽  
Erni Ma ◽  
Jinzhen Cao ◽  
...  
Keyword(s):  
Cell Wall ◽  
Moisture Content ◽  
Spin Relaxation ◽  
Cell Walls ◽  
Lignin Content ◽  
Theoretical Estimate ◽  
Relaxation Times ◽  
Dry Weight ◽  
Hemicellulose Removal ◽  
Water Saturated

To investigate the effects of changes in biopolymer composition on moisture in acetylated poplar wood (Populus euramericana Cv.), the acetylation of control wood was compared to the acetylation of wood with reduced hemicellulose or lignin content (about 9% reduction of total specimen dry weight in both cases). Time-domain nuclear magnetic resonance relaxometry of water-saturated wood gave spin–spin relaxation times (T2) of water populations, while deuteration in a sorption balance was used to characterize the hydroxyl accessibility of the wood cell walls. As expected, the acetylation of pyridine-swelled wood reduced hydroxyl accessibility and made the cell wall less accessible to water, resulting in a reduction of cell wall moisture content by about 24% compared with control wood. Hemicellulose loss per se increased the spin–spin relaxation time of cell wall water, while delignification had the opposite effect. The combined effect of hemicellulose removal and acetylation caused more than a 30% decrease of cell wall moisture content when compared with control wood. The acetylated and partially delignified wood cell walls contained higher cell wall moisture content than acetylated wood. An approximate theoretical calculation of hydroxyl accessibility for acetylated wood was in the low range, but it agreed rather well with the measured accessibility, while acetylated and partially hemicellulose-depleted and partially delignified wood for unknown reasons resulted in substantially lower hydroxyl accessibilities than the theoretical estimate.

scholarly journals Improvement of interfacial interaction in impregnated wood via grafting methyl methacrylate onto wood cell walls

Holzforschung ◽  
2020 ◽  
Vol 74 (10) ◽  
pp. 967-977
Author(s):  
Youming Dong ◽  
Michael Altgen ◽  
Mikko Mäkelä ◽  
Lauri Rautkari ◽  
Mark Hughes ◽  
...  
Keyword(s):  
Cell Wall ◽  
Methyl Methacrylate ◽  
Cell Walls ◽  
Wood Cell Wall ◽  
Principal Component ◽  
Interfacial Interaction ◽  
Raman Microscopy ◽  
Hydroxyl Groups ◽  
Confocal Raman Microscopy ◽  
Confocal Raman

AbstractImproving the interaction between the wood cell wall and a modifying agent is fundamental to enhancing the efficacy of wood modification. The extent of interaction is, nevertheless, difficult to evaluate due to the highly heterogeneous nature of the modified wood. In this study, methacryl groups were grafted onto the wood cell wall polymers, via the reaction between 2-isocyanatoethyl methacrylate (IEMA) and hydroxyl groups, to improve their compatibility and reactivity. Subsequently, methyl methacrylate (MMA) was introduced into methacrylated wood and copolymerized with the bonded methacryl groups. The distribution of IEMA and poly MMA (PMMA) in the wood cell walls was investigated by scanning electron microscopy (SEM) and confocal Raman microscopy. The results showed that MMA penetrated the wood cell walls and formed strong interfacial interaction, which was confirmed by confocal Raman microscopy combined with principal component analysis (PCA). With copolymerization, the highest anti-swelling efficiency (ASE) (57%) was achieved, because of the effect of methacrylation. Compared to the reference, the water resistance and hardness were significantly improved. In addition, the dynamic wettability was also altered largely due to copolymerization.

Chemical modification of Petersianthus macrocarpus (essia), to determine whether durability depends on bulking or hydroxyl substitution

2018 ◽  
Vol 3 (3) ◽  
pp. 92-96
Author(s):  
Eric D. Marfo
Keyword(s):  
Cell Wall ◽  
Decay Resistance ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Percentage Weight Loss ◽  
Weight Percentage ◽  
Chemically Modified ◽  
Cell Wall Polymers ◽  
Percentage Weight ◽  
Modified Wood

Wood is a biodegradable material. Decay resistance of wood is improved when the wood is chemically modified. The decayresistance of a chemically modified wood is improved as the modification stabilizes the cell wall polymers against enzyme attackdue to the blocking of accessible hydroxyl groups of the cell wall polymers which reduces the amount of water for hydrolysis. Theimproved durability of the modified wood as a result of reducing the amount of water molecules into the cell wall for hydrolysiswill depend on either bulking or percentage hydroxyl substitution (%OH). Petersianthus macrocarpus (essia), a tropical hardwoodspecies was chemically modified with acetic anhydride (AA) and pentanoic anhydride (PA) in dry pyridine to improve its decayresistance. Graveyard test was used to analyze the effect of the modification on the decay resistance of the wood in twelve weeksin-ground contact. Percentage weight loss and visual decay grades were used to evaluate whether the decay resistance dependson weight percentage gain or percentage hydroxyl substitution. The decay resistance of the modified samples were found to bedependent on bulking.

scholarly journals Dimensional stabilisation of Scots pine (Pinus sylvestris L.) sapwood by reaction with maleic anhydride and sodium hypophosphite

2021 ◽  
Author(s):  
Injeong Kim ◽  
Olov Karlsson ◽  
Dennis Jones ◽  
George Mantanis ◽  
Dick Sandberg
Keyword(s):  
Maleic Anhydride ◽  
Chemical Modification ◽  
Scots Pine ◽  
Dimensional Stability ◽  
Hydrolytic Stability ◽  
Treatment Temperature ◽  
Sodium Hypophosphite ◽  
Cross Linking ◽  
High Concentration ◽  
Weight Percentage

AbstractWood has the ability to absorb and desorb moisture, which can affect its dimensional size when in use. Limiting this can provide products with greater shape stability and less stresses on external coatings. One method that has been investigated for achieving this has been through chemical modification. In this work, the dimensional stabilisation imparted to Scots pine sapwood by chemical modification with maleic anhydride (MA) combined with sodium hypophosphite (SHP) was investigated. The influence of concentration of MA, treatment temperature and treatment period on weight percent gain (WPG) and bulking coefficient (BC) during treatment with MA and SHP of wood was studied. Furthermore, dimensional stability was determined by the water soak/oven dry method (wet-dry cycle) through five cycles in order to determine the hydrolytic stability of the ester bond and any potential cross-linking reactions. Wood blocks (20 × 20 × 10 mm) modified with MA combined with SHP exhibited lower weight loss following water soaking than unmodified blocks or MA-treated blocks. Wood blocks modified with MA and SHP showed the best anti-swelling efficiency and minimum wet-volume (water-saturated). However, as the concentration of SHP increased, dimensional stability was diminished without any increase in weight percentage gain after water soaking. When combined with FTIR results, it appeared that the modification with MA and SHP seemed to form cross-linking between wood constituents, though high concentration of SHP did not seem to result in additional cross-linking.

scholarly journals Cell Wall Bulking by Maleic Anhydride for Wood Durability Improvement

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 367 ◽  
Author(s):  
Mingming He ◽  
Dandan Xu ◽  
Changgui Li ◽  
Yuzhen Ma ◽  
Xiaohan Dai ◽  
...  
Keyword(s):  
Cell Wall ◽  
Maleic Anhydride ◽  
Wood Cell Wall ◽  
Brown Rot ◽  
Decay Resistance ◽  
White Rot ◽  
White Rot Fungus ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Decay Fungi

Wood is susceptible to swelling deformation and decay fungi due to moisture adsorption that originates from the dynamic nanopores of the cell wall and the abundant hydroxyl groups in wood components. This study employed as a modifier maleic anhydride (MAn), with the help of acetone as solvent, to diffuse into the wood cell wall, bulk nanopores, and further chemically bond to the hydroxyl groups of wood components, reducing the numbers of free hydroxyl groups and weakening the diffusion of water molecules into the wood cell wall. The derived MAn-bulked wood, compared to the control wood, presented a reduction in water absorptivity (RWA) of ~23% as well as an anti-swelling efficiency (ASE) of ~39% after immersion in water for 228 h, and showed an improvement in decay resistance of 81.42% against white-rot fungus and 69.79% against brown-rot fungus, respectively. The method of combined cell wall bulking and hydroxyl group bonding could effectively improve the dimensional stability and decay resistance with lower doses of modifier, providing a new strategy for wood durability improvement.

Juvenile and Compression Wood Cell Wall Layers Differ in Lignin Structure in Norway Spruce and Scots Pine

IAWA Journal ◽  
2008 ◽  
Vol 29 (1) ◽  
pp. 47-57 ◽  
Author(s):  
Eija Kukkola ◽  
Pekka Saranpää ◽  
Kurt Fagerstedt
Keyword(s):  
Cell Wall ◽  
Norway Spruce ◽  
Scots Pine ◽  
Cell Walls ◽  
Compression Wood ◽  
Wood Cell Wall ◽  
Outer Part ◽  
Wall Layer ◽  
Mature Wood ◽  
Normal Wood

Dibenzodioxocin, an 8-ring substructure of lignin identified in the mid- 1990's, is known to occur in softwood cell walls especially in the S3-layers of normal wood. In this study the lignin substructure was immunolocalised in juvenile and mature wood as well as in different degrees of compression wood of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.). In juvenile wood of Norway spruce, dibenzodioxocin was hardly present in the tracheid cell wall, while in Scots pine some dibenzodioxocin was found evenly distributed in the S2-layers. In mature normal wood, dibenzodioxocin was localised in the S3-layers in both Scots pine and Norway spruce. In contrast, in compression wood tracheids of Scots pine, where the S3-layer is not present, dibenzodioxocin was found in the S1-layers and in the outer part of the S2-layers, while in Norway spruce the innermost cell wall layer showed a strong signal. These findings support the idea that in mature wood the condensed dibenzodioxocin structure is formed in Norway spruce at the end of lignification, when the supply of monolignols and probably also hydrogen peroxide is diminishing. The reasons for Scots pine juvenile and compression wood showing a different pattern of dibenzodioxocin labelling is discussed.

Silicification of wood-cell walls

1994 ◽  
Vol 52 ◽  
pp. 428-429
Author(s):  
S. E. Keckler ◽  
D. M. Dabbs ◽  
N. Yao ◽  
I. A. Aksay
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Cell Walls ◽  
Lignin Content ◽  
Resin Composite ◽  
Middle Lamella ◽  
Cellulose Fibers ◽  
Complex Structures ◽  
Rich Region ◽  
Inorganic Precursors

Cellular organic structures such as wood can be used as scaffolds for the synthesis of complex structures of organic/ceramic nanocomposites. The wood cell is a fiber-reinforced resin composite of cellulose fibers in a lignin matrix. A single cell wall, containing several layers of different fiber orientations and lignin content, is separated from its neighboring wall by the middle lamella, a lignin-rich region. In order to achieve total mineralization, deposition on and in the cell wall must be achieved. Geological fossilization of wood occurs as permineralization (filling the void spaces with mineral) and petrifaction (mineralizing the cell wall as the organic component decays) through infiltration of wood with inorganics after growth. Conversely, living plants can incorporate inorganics into their cells and in some cases into the cell walls during growth. In a recent study, we mimicked geological fossilization by infiltrating inorganic precursors into wood cells in order to enhance the properties of wood. In the current work, we use electron microscopy to examine the structure of silica formed in the cell walls after infiltration of tetraethoxysilane (TEOS).

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