Penetration of Different Liquids in Wood-Based Composites: The Effect of Adsorption Energy

The penetration properties of three different liquids on the surface of medium-density fiberboard (MDF) and particleboard panels were studied. Water, as a polar liquid, was compared to two other less polar liquids (namely, ethanol and kerosene) with significantly larger molecules. Measurement of penetration time and wetted area demonstrated significantly higher values for water in comparison with the other two liquids, in both composite types. Calculation of adsorption energies, as well as adsorption distances, of the three liquid molecules on hemicellulose showed higher potentiality of water molecules in forming bonds on hemicellulose. However, comparison of the adsorption energies of cellulose with hemicellulose indicated a higher impact of the formation of bonds between hydroxyl groups in water and cellulose in hindering the penetration of water molecules into the composite textures. It was concluded that the formation of strong and stable bonds between the hydroxyl groups in water and cellulose resulted in a significant increase in penetration time and wetted area.

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Fractionation of Waste MDF by Steam Refining

Molecules ◽

10.3390/molecules25092165 ◽

2020 ◽

Vol 25 (9) ◽

pp. 2165 ◽

Cited By ~ 3

Author(s):

Sebastian Hagel ◽

Bodo Saake

Keyword(s):

Degradation Products ◽

Medium Density Fiberboard ◽

The Other ◽

Nitrogen Compounds ◽

Medium Density ◽

Steam Refining ◽

Carbohydrate Hydrolysis ◽

Extract Fraction ◽

Expected Increase ◽

Populus Spp

In view of the expected increase in available waste medium-density fiberboard (MDF) and the current insufficient and unsatisfactory disposal capacities, efficient ways of recycling the waste material need to be developed. In this study, the potential of steam refining as a method to hydrolyze the resins, isolate fibers, and obtain a hemicellulose-rich extract available for further utilization in the context of a biorefinery was assessed. Two different MDF waste samples, as well as poplar (Populus spp.) and spruce (Picea spp.) wood chips for benchmarking, were treated over a severity range from 2.47 to 3.95. The separated fiber and extract fractions were analyzed with regard to yield, content of carbohydrates, acids, degradation products, and nitrogen. A fiber fraction of more than 70% yield and an extract containing up to 30% of carbohydrates for further processing can be gained by steam-refining waste MDF. At low severities, most of the nitrogen-based compounds are solubilized. Increasing the severity leads to a decrease in nitrogen in the extract as the nitrogen compounds are converted into volatiles. A non-hydrolysable resin residue remains on the fibers, independent of the treatment severity. In comparison to the benchmark samples, the extract fraction of waste MDF shows a high pH of 8 and high amounts of acetic and formic acid. The generation of furfural and 5-hydroxymethylfurfural (5-HMF) on the other hand is suppressed. Distinct differences in carbohydrate hydrolysis behavior between waste MDF and conventional wood can be observed. Especially, the mannose-containing constituents seem to be resistant to hydrolysis reactions in the milieu created in MDF fractionation.

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Research into Corner L Separable Assemblies in Storage Furniture

Drvna industrija ◽

10.5552/drvind.2021.1924 ◽

2021 ◽

Vol 72 (1) ◽

pp. 89-98

Author(s):

Ivica Župčić ◽

Ivan Žulj ◽

Igor Kamerman ◽

Ivica Grbac ◽

Zoran Vlaović

Keyword(s):

Joint Strength ◽

Medium Density Fiberboard ◽

Bending Moment ◽

Trade Mark ◽

The Other ◽

Medium Density ◽

Research Results ◽

Other Hand ◽

Wear And Tear ◽

The Impact

This research is based on the testing of the impact of the board (particleboard and medium density fiberboard (MDF)) and hardware type used to connect the sides and the bottom or top of the storage furniture on the joint strength. The hardwares of the following trade mark were used: the confirmat screw, Minifix, Maxifix, Stablofix, RV and Solo 32. Such hardwares make it possible to disassemble the furniture as well as to assemble it (when moving the furniture) without reducing joint strength when reassembling it due to wear and tear on the material (with the exception of the confirmant screw). Research results showed that assemblies with the Maxifix hardware installed in the MDF base exhibited the highest values of bending moment (the average bending moment of 85.88 Nm). On the other hand, assemblies with the Minifix hardware installed in the particleboard exhibited the lowest values of bending moment (over three times lower than the Maxifix) (the average bending moment of 24.50 Nm). Assemblies with the confirmat screw exhibited satisfactory results, although, aesthetic requirements seem to be the main problem here (the average bending moment of 40.38 Nm for the particleboard and of 64.24 Nm for the MDF).

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Hydrogen-bond network in cyclodecaamylose hydrate at 20 K; neutron diffraction study of novel structural motifs band-flip and kink in α-(1→4)-D-glucoside oligosaccharides

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768101014288 ◽

2001 ◽

Vol 57 (6) ◽

pp. 833-841 ◽

Cited By ~ 9

Author(s):

K. Imamura ◽

O. Nimz ◽

J. Jacob ◽

D. Myles ◽

S. A. Mason ◽

...

Keyword(s):

Hydrogen Bonds ◽

Neutron Diffraction ◽

Diffraction Study ◽

Structure Refinement ◽

Neutron Diffraction Study ◽

The Other ◽

Water Molecules ◽

Hydroxyl Groups ◽

Neutron Density ◽

Asymmetric Unit

A single-crystal neutron diffraction study of cyclodecaamylose (CA10) was carried out at 20 K. CA10 crystallizes with 27.18 water molecules [(C6H10O5)10·27.18H2O] in space group C2 with unit-cell constants a = 29.31 (5), b = 9.976 (10), c = 19.34 (2) Å, β = 121.07 (2)°. The asymmetric unit contains a half molecule of CA10 and 13.59 water molecules, the other half being related by a crystallographic twofold rotation axis. All H atoms except two water H atoms could be located from difference neutron-density maps; structure refinement converged at R = 0.635. Two of the five CH2—O6 groups and one of the 15 O2, O3 hydroxyl groups of CA10 are twofold orientationally disordered. A total of 13.59 water molecules in the asymmetric unit are distributed over 23 positions; 20 of which are in the CA10 cavity, and the other three occupy intermolecular interstices. Of the 123 symmetry-independent hydrogen bonds, 25 (= 20%) are three-centered and 7 (= 6%) are four-centered. Water molecules and O—H groups of CA10 form an extended network with cooperative O—H...O—H...O—H hydrogen bonds. They are arranged in 11 polygons with three, four, five, six and eight O—H bonds and in homodromic, antidromic and heterodromic arrangements. Nine polygons are located within the cavity and the others are outside.

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Synthesis Mechanism of an Environment-Friendly Sodium Lignosulfonate/Chitosan Medium-Density Fiberboard Adhesive and Response of Bonding Performance to Synthesis Mechanism

Materials ◽

10.3390/ma13245697 ◽

2020 ◽

Vol 13 (24) ◽

pp. 5697

Author(s):

Xiaodi Ji ◽

Minghui Guo ◽

Li Zhu ◽

Wenxin Du ◽

Hongbin Wang

Keyword(s):

Medium Density Fiberboard ◽

Hydroxyl Groups ◽

Medium Density ◽

Amino Groups ◽

Sodium Lignosulfonate ◽

Synthesis Mechanism ◽

Environment Friendly ◽

Bonding Performance ◽

3D Network ◽

Mass Ratios

Environment-friendly medium-density fiberboards (MDFs) prepared using sodium lignosulfonate/chitosan adhesives (L/C) show potential in environment-friendly wood-based panel application. However, the synthesis mechanism of this adhesive and the relationships between synthesis mechanism and bonding performance were not discussed in depth. Herein, the synthesis mechanism of L/C was explored in detail based on characterizations of L/C with different mass ratios of sodium lignosulfonate to chitosan by Fourier-transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. For L/C with different mass ratios of sodium lignosulfonate to chitosan, the corresponding bonding performance was also determined based on characterizations of mechanical and dimensional performance of MDFs. Results showed a 3D network structure of L/C formed through the hydrogen linkages among hydroxyl groups in sodium lignosulfonate and hydroxyl and amino groups in chitosan, amide linkages resulted from reaction between carbonyl groups in sodium lignosulfonate and amino groups in chitosan, and sulfonamide linkages originated from reaction between sulfonic groups in sodium lignosulfonate and amino groups in chitosan. The mechanical performance of MDF was closely related to the 3D network and amino groups of L/C, while the dimensional performance of MDF was negatively affected by sodium lignosulfonate. The MDFs with 1:3 and 1:2 mass ratios of sodium lignosulfonate to chitosan showed superior mechanical properties and comparable dimensional performance with a commercial panel.

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Disorder in Cyclodextrin Clathrates: X-ray Diffuse Scattering Analysis of α-Cyclodextrin Cyclopentanone Hydrate

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768197000414 ◽

1997 ◽

Vol 53 (4) ◽

pp. 673-679 ◽

Cited By ~ 1

Author(s):

G. Le Bas ◽

J. Doucet

Keyword(s):

Crystal Growth ◽

Neutron Diffraction ◽

Structure Determination ◽

Diffuse Scattering ◽

The Other ◽

Water Molecules ◽

Hydroxyl Groups ◽

Asymmetric Unit ◽

Orientational Disorder ◽

X Ray

Most of the cyclodextrin clathrates display disorder, consequently the structure determination is often difficult to carry out. Previous studies by X-ray and neutron diffraction have shown that the \alpha-cyclodextrin cyclopentanone hydrate crystallizes in a channel-like structure with hexagonal P6 symmetry. Two inclusion complexes were found in the asymmetric unit; there is an orientational disorder of the guest with six positions found in one host cavity, three in the other. In addition, certain host hydroxyl groups and water molecules were found to be disordered and their disorder was correlated with the guest disorder. In this paper we investigate X-ray diffuse scattering phenomena in order to go further in the interpretation of disorder. Complicated diffuse scattering patterns revealed a variety of disorder phenomena. Some were not shown by the average structure determination. The interpretation of the results (structure in domains, supercell and vacancies) helps to explain the rotational disorder of the guest and some observed strains of the averaged structure. The description of different microstructures may be of interest for crystal growth and inclusion chemistry.

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The crystal structure of sucrose sodium bromide dihydrate

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1947.0075 ◽

1947 ◽

Vol 190 (1021) ◽

pp. 257-272 ◽

Cited By ~ 45

Keyword(s):

Crystal Structure ◽

Direct Proof ◽

The Other ◽

Sodium Bromide ◽

Water Molecules ◽

Hydroxyl Groups ◽

Pyranose Ring ◽

Complete Structure ◽

The Mean ◽

First Time

The complete crystal structure of sucrose sodium bromide dihydrate has been determined. The crystals are orthorhombic, with space-group P 2 1 2 1 2 1 , and cell-edges a =21.92, b =9.72, c =8.43 A. The bromine positions were obtained from Patterson-Harker syntheses, and the signs of the F ’s of the (0 kl ), ( h 0 l ) and ( hk 0) planes from the change of intensity from the chloride to bromide compounds. Fourier projections parallel to the three axes were used to determine the complete structure. In the structure the pyranose ring of the molecule is of the Sachse trans form. The furanose ring is an unexpectedly compact grouping, and one member of the ring is displaced from the plane of the other four. The configuration of both rings is such as to allow the groups attached to the ring atoms to approach as nearly as possible to the mean plane of each ring. Direct proof that sucrose may be described as α - d -glucopyranosido- β - d -fructofuranoside has been obtained for the first time. The sucrose molecules are held together by bonds from the hydroxyl groups to the Na and Br ions and to the water molecules, the hydroxyl groups each having two external bonds. The method used of reducing the observed intensities to an absolute scale is described, and the proof of the correctness of the structure is given as a set of diagrams of calculated and observed electron density.

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

10.26434/chemrxiv.8075204 ◽

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.

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Calcium carbonate modified urea–formaldehyde resin adhesive for strength enhanced medium density fiberboard production

RSC Advances ◽

10.1039/d1ra04316a ◽

2021 ◽

Vol 11 (40) ◽

pp. 25010-25017

Author(s):

Li Lu ◽

Yan Wang ◽

Tianhua Li ◽

Supeng Wang ◽

Shoulu Yang ◽

...

Keyword(s):

Calcium Carbonate ◽

Urea Formaldehyde ◽

Medium Density Fiberboard ◽

Urea Formaldehyde Resin ◽

Formaldehyde Resin ◽

Medium Density ◽

Ionic Bond ◽

Resin Adhesive ◽

Uf Resin ◽

Modified Urea

Reactions between CaCO3 and CH2O2 during polycondensation of UF resin produce Ca2+. Ionic bond complexation binds Ca2+ with UF resin. The UF resin crystalline percentage decreases from 26.86% to 22.71%. IB strength of resin bonded fiberboard increases from 0.75 to 0.94 MPa.

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