Delineating pMDI model reactions with loblolly pine via solution-state NMR spectroscopy. Part 2. Non-catalyzed reactions with the wood cell wall

Holzforschung ◽  
2011 ◽  
Vol 65 (2) ◽  
Author(s):  
Daniel J. Yelle ◽  
John Ralph ◽  
Charles R. Frihart
Keyword(s):  
Cell Wall ◽  
Moisture Content ◽  
Loblolly Pine ◽  
Quantum Coherence ◽  
Oriented Strand Board ◽  
Hydroxyl Groups ◽  
High Concentration ◽  
Model Compounds ◽  
Covalent Bonds ◽  
Solution State

Abstract Solution-state NMR provides a powerful tool to observe the presence or absence of covalent bonds between wood and adhesives. Finely ground wood can be dissolved in an NMR-compatible solvent system containing dimethylsulfoxide-d 6 and N-methylimidazole-d 6 , in which the wood polymers remain largely intact. High-resolution solution-state two-dimensional NMR correlation experiments, based on 13C–1H one-bond heteronuclear single quantum coherence, allow structural analysis of the major cell wall components. This technique was applied to loblolly pine that was treated with polymeric methylene diphenyl diisocyanate (pMDI) related model compounds under controlled moisture and temperature conditions. Chemical shifts of carbamates formed between the pMDI model compounds and loblolly pine were determined. The results show that: (a) under dry conditions and a high concentration of isocyanate, carbamates will form preferentially with side-chain hydroxyl groups on β-aryl ether and phenylcoumaran-linked lignin units in a swelling solvent; (b) phenyl isocyanate is more capable of derivatization in the cell wall than the bulkier 4-benzylphenyl isocyanate; (c) at 5% and 14% moisture content, detectable carbamates on lignin side-chains dramatically decrease; and (d) under typical conditions of industrial oriented strand-board production in a hot press at 5% and 14% moisture content, no carbamate formation was detected.

Delineating pMDI model reactions with loblolly pine via solution-state NMR spectroscopy. Part 1. Catalyzed reactions with wood models and wood polymers

Holzforschung ◽  
2011 ◽  
Vol 65 (2) ◽  
Author(s):  
Daniel J. Yelle ◽  
John Ralph ◽  
Charles R. Frihart
Keyword(s):  
Nmr Spectroscopy ◽  
Loblolly Pine ◽  
Model Compound ◽  
Oriented Strand Board ◽  
Chemical Shifts ◽  
Hydroxyl Group ◽  
Model Compounds ◽  
Solution State ◽  
Adhesive Interactions ◽  
Catalyzed Reactions

Abstract To better understand adhesive interactions with wood, reactions between model compounds of wood and a model compound of polymeric methylene diphenyl diisocyanate (pMDI) were characterized by solution-state NMR spectroscopy. For comparison, finely ground loblolly pine sapwood, milled-wood lignin and holocellulose from the same wood were isolated and derivatized with the pMDI model compound. One-bond 13C–1H correlation (HSQC) experiments on derivatized and dissolved ball-milled wood revealed which hydroxyl group positions of the cell wall polymers reacted with the pMDI model compound to form carbamates. The chemical shifts of the derivatized model compounds correspond precisely to the chemical shifts of derivatized wood polymers. These model experiments will be taken as a basis in the next phase of our research (Part 2), in which the reactions of pMDI model compounds will be studied with intact wood cell walls under conditions similar to those used in oriented strand-board production.

scholarly journals Thermal modification of wood—a review: chemical changes and hygroscopicity

2021 ◽  
Author(s):  
Callum Hill ◽  
Michael Altgen ◽  
Lauri Rautkari
Keyword(s):  
Cell Wall ◽  
Moisture Content ◽  
Dimensional Stability ◽  
Thermal Modification ◽  
Hydroxyl Groups ◽  
Water Leaching ◽  
Topic Area ◽  
Sorption Behaviour ◽  
Oh Groups

Abstract Thermal modification is a well-established commercial technology for improving the dimensional stability and durability of timber. Numerous reviews of thermally modified timber (TMT) are to be found in the scientific literature, but until now a review of the influence of cell wall moisture content during the modification process on the properties of TMT has been lacking. This paper reviews the current state of knowledge regarding the hygroscopic and dimensional behaviour of TMT modified under dry (cell wall at nearly zero moisture content) and wet (cell wall contains moisture) conditions. After an overview of the topic area, the review explores the literature on the thermal degradation of the polysaccharidic and lignin components of the cell wall, as well as the role of extractives. The properties of TMT modified under wet and dry conditions are compared including mass loss, hygroscopic behaviour and dimensional stability. The role of hydroxyl groups in determining the hygroscopicity is discussed, as well as the importance of considering the mobility of the cell wall polymers and crosslinking when interpreting sorption behaviour. TMT produced under wet processing conditions exhibits behaviour that changes when the wood is subjected to water leaching post-treatment, which includes further weight loss, changes in sorption behaviour and dimensional stability, but without any further change in accessible hydroxyl (OH) content. This raises serious questions regarding the role that OH groups play in sorption behaviour. Graphical abstract

Properties of Gliricidia Wood (Gliricidia sepium) lntercropped with Cocoa (Theobroma cocoa) in Malaysia

2014 ◽  
Vol 11 (1) ◽  
pp. 51
Author(s):  
Mohd Helmy Ibrahim ◽  
Mohd Nazip Suratman ◽  
Razali Abd Kader
Keyword(s):  
Cell Wall ◽  
Specific Gravity ◽  
Moisture Content ◽  
Wall Thickness ◽  
Age Groups ◽  
Gliricidia Sepium ◽  
Cell Wall Thickness ◽  
Tree Age ◽  
Lumen Diameter ◽  
Significant Difference

Trees planted from agroforestry practices can become valuable resources in meeting the wood requirements of many nations. Gliricidia sepium is an exotic species introduced to the agricultural sector in Malaysia mainly for providing shade for cocoa and coffee plantations. This study investigates its wood physical properties (specific gravity and moisture content) and fibre morphology (length, lumen diameter and cell wall thickness) of G. sepium at three intervals according to age groups ( three, five and seven years of ages). Specific gravity (0.72) was significantly higher at seven years ofage as compared to five (0.41) and three (0.35) years age group with a mean of 0.43 (p<0.05). Mean moisture content was 58.3% with no significant difference existing between the tree age groups. Fibre diameter (22.4 mm) was significantly lower (p<0.05) for the trees which were three years of age when compared to five and seven years age groups (26.6 mm and 24. 7 mm), respectively. Means of fibre length, lumen diameter and cell wall thickness were 0.83 mm, 18.3 mm, and 6.2 mm, respectively, with no significant differences detected between trees in all age groups. Further calculation on the coefficient of suppleness and runkel ratio suggest that wood from G.sepium may have the potential for insulation board manufacturing and paper making. However, future studies should experiment the utilisation of this species for these products to determine its full potential.

QM/MM Simulations of Organic Phosphorus Adsorption at the Diaspore-Water Interface

2019 ◽  
Author(s):  
Prasanth Babu Ganta ◽  
Oliver Kühn ◽  
Ashour Ahmed
Keyword(s):  
Interaction Energy ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Water Interface ◽  
Mineral Surfaces ◽  
Soil Mineral ◽  
Phosphorus Adsorption ◽  
Covalent Bonds ◽  
Binding Mechanisms

The phosphorus (P) immobilization and thus its availability for plants are mainly affected by the strong interaction of phosphates with soil components especially soil mineral surfaces. Related reactions have been studied extensively via sorption experiments especially by carrying out adsorption of ortho-phosphate onto Fe-oxide surfaces. But a molecular-level understanding for the P-binding mechanisms at the mineral-water interface is still lacking, especially for forest eco-systems. Therefore, the current contribution provides an investigation of the molecular binding mechanisms for two abundant phosphates in forest soils, inositol hexaphosphate (IHP) and glycerolphosphate (GP), at the diaspore mineral surface. Here a hybrid electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) based molecular dynamics simulation has been applied to explore the diaspore-IHP/GP-water interactions. The results provide evidence for the formation of different P-diaspore binding motifs involving monodentate (M) and bidentate (B) for GP and two (2M) as well as three (3M) monodentate for IHP. The interaction energy results indicated the abundance of the GP B motif compared to the M one. The IHP 3M motif has a higher total interaction energy compared to its 2M motif, but exhibits a lower interaction energy per bond. Compared to GP, IHP exhibited stronger interaction with the surface as well as with water. Water was found to play an important role in controlling these diaspore-IHP/GP-water interactions. The interfacial water molecules form moderately strong H-bonds (HBs) with GP and IHP as well as with the diaspore surface. For all the diaspore-IHP/GP-water complexes, the interaction of water with diaspore exceeds that with the studied phosphates. Furthermore, some water molecules form covalent bonds with diaspore Al atoms while others dissociate at the surface to protons and hydroxyl groups leading to proton transfer processes. Finally, the current results confirm previous experimental conclusions indicating the importance of the number of phosphate groups, HBs, and proton transfers in controlling the P-binding at soil mineral surfaces.

scholarly journals Structural characteristics of plant cell wall elucidated by solution-state 2D NMR spectroscopy with an optimized procedure

2020 ◽  
Vol 9 (1) ◽  
pp. 650-663
Author(s):  
Wanwan Wang ◽  
Jibao Cai ◽  
Zhenyu Xu ◽  
Yi Zhang ◽  
Fanchao Niu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Quantum Coherence ◽  
Nmr Spectra ◽  
Plant Cell Wall ◽  
Milling Time ◽  
Structural Characteristics ◽  
2D Nmr ◽  
2D Nmr Spectroscopy ◽  
Complete Representation

AbstractA method was developed for rapid qualitative determination of lignocellulose in the tobacco cell wall by utilizing 2D heteronuclear single quantum coherence NMR spectra (2D HSQC NMR). Traditional methods for analyzing the structure of lignocellulose involve many steps of separation and extraction, which is labor-intensive. In this work, the whole cell wall was milled and dissolved in deuterium solvent. The solvent dimethylsulfoxide (DMSO-d6) containing hexamethylphosphoramide (HMPA-d18) enhanced swelling of the sample and gave high-resolution spectra. The tobacco samples are ball milled at different ball milling times, and the state of the particles is observed through an electron microscope, and then the probability of the particles being less than 5 µm is counted. Through the comparison of the abundance and integration of the peak signals in the spectra under different transmittances, it was determined that when the milling time was 6 h, the quality of the NMR spectra was the best. The optimum conditions of characterizing tobacco structure were DMSO-d6/HMPA-d18 solution and 6 h milling time. Under these conditions, complete representation of the structure of lignocellulose and simplified process could be achieved.

Sensitivity of acoustic tools to variation in equilibrium moisture content of small clear samples of loblolly pine (Pinus taeda)

2017 ◽  
Vol 15 (1) ◽  
pp. 10-20 ◽  
Author(s):  
Charles Essien ◽  
Brian K. Via ◽  
Thomas Gallagher ◽  
Timothy Mcdonald ◽  
Lori Eckhardt
Keyword(s):  
Moisture Content ◽  
Pinus Taeda ◽  
Equilibrium Moisture Content ◽  
Loblolly Pine

scholarly journals Performance of Oriented Strand Board Made with Soy Substituted Resin in Termite Choice Tests with Southern Yellow Pine

2021 ◽  
Vol 71 (3) ◽  
pp. 199-208
Author(s):  
Qingzheng Cheng ◽  
Juliet D. Tang ◽  
Chengfeng Zhou ◽  
Wei Jiang ◽  
Lixia Hu ◽  
...  
Keyword(s):  
Weight Loss ◽  
Moisture Content ◽  
Oriented Strand Board ◽  
Soy Flour ◽  
Water Repellent ◽  
Rating Data ◽  
Structural Applications ◽  
Choice Tests ◽  
Yellow Pine ◽  
Southern Yellow Pine

Abstract Soy flour was evaluated as a partial substitute for resin in the manufacture of oriented strand board (OSB), a wood-based composite that often replaces solid lumber and plywood in structural applications in the construction industry. Since the presence of soy could alter OSB biodegradation properties, termite resistance of OSB panels made with 0, 10, and 20 percent of polymeric methylene diphenyl diisocyanate (pMDI) resin substituted with soy flour (OSB0, OSB10, and OSB20, respectively) was investigated. Single choice tests between three types of OSB and southern yellow pine (SYP) solid wood and an OSB choice test (OSB0 vs. OSB10) were evaluated. Results indicated that termites always showed a preference for SYP, with the OSB becoming less palatable when soy flour was present. Percentage weight losses for OSB0, OSB10, and OSB20 were 5.7×, 8.4×, and 8.6× less, respectively, compared with SYP. In the absence of SYP, termites did not differentiate OSB0 from OSB10, with OSB10 showing 1.5× less weight loss compared with OSB0. Visual rating data supported weight loss data, except significantly less damage was only found when the choice paired SYP with OSB made with soy (OSB10 or OSB20). Termite consumption preference for SYP was explained by differences in water absorption kinetics. SYP reached saturation (105% moisture content) within 1 week on moist sand, while moisture content of OSB composites slowly climbed to 79 percent over 4 weeks, never reaching a plateau. Lower moisture content was due to the presence of water-repellent resin and wax in the OSB.

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