scholarly journals Tuning of adhesion and disintegration of oxidized starch adhesives for the recycling of medium density fiberboard

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 5156-5178
Author(s):  
Muhammad Adly Rahandi Lubis ◽  
Byung-Dae Park ◽  
Min-Kug Hong
Keyword(s):  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Physical And Mechanical Properties ◽  
Formaldehyde Emission ◽  
Molar Ratio ◽  
Medium Density ◽  
Molar Ratios ◽  
Oxidized Starch ◽  
Cross Linker ◽  
The Cross

Oxidized starch (OS) adhesives with a balance between their adhesion and disintegration properties were prepared by controlling the degree of oxidation and modifying the cross-linker type and level to replace urea-formaldehyde (UF) resins for easy recycling of medium density fiberboard (MDF). Four molar ratios of H2O2/starch, two types of cross-linker, i.e., blocked-pMDI (B-pMDI) and citric acid (CA), and three levels of the cross-linkers were employed to tailor the performance of the OS adhesives. The OS reacted with the isocyanate groups from the B-pMDI to form amide linkages, while it formed ester linkages by reacting with the CA. The resulting B-pMDI/OS-bonded MDF had better physical and mechanical properties than the CA/OS-bonded MDF, with comparable adhesion (0.34 MPa) to UF resins and ten times greater degree of fiber disintegration than UF resins. The combination of a 0.5 molar ratio OS with 7.5 wt% of B-pMDI produced MDF exhibiting an optimal balance between adhesion and disintegration, suggesting that such OS adhesives could someday replace UF resins in manufacturing and recycling of MDF without formaldehyde emission.

scholarly journals Effect of Embedment of MWCNTs for Enhancement of Physical and Mechanical Performance of Medium Density Fiberboard

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 29
Author(s):  
Waheed Gul ◽  
Hussein Alrobei ◽  
Syed Riaz Akbar Shah ◽  
Afzal Khan ◽  
Abid Hussain ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Research Work ◽  
Multiwall Carbon Nanotubes ◽  
Physical And Mechanical Properties ◽  
Formaldehyde Emission ◽  
Modulus Of Rupture ◽  
Formaldehyde Resin ◽  
Medium Density

In this research work effect of embedment of multiwall carbon nanotubes (MWCNTs) on the physical and mechanical properties of medium density fiberboard (MDF) have been investigated. The MWCNTs were embedded in urea formaldehyde resin (UF) at 0, 1.5%, 3% and 5% concentrations by weight for the manufacturing of nano-MDF. The addition of these nanoparticles enhanced thermal conductivity by 24.2% reduced curing time by 20% and controlled formaldehyde emission by 59.4%. The internal bonding (I.B), modulus elasticity (MOE), modulus of rupture (MOR), thickness swelling (Ts) and water absorption (WA) properties were improved significantly by 21.15%, 30.2%, 28.3%, 44.8% and 29% respectively as compared to controlled MDF.

Effect of calcite addition on technical properties and reduction of formaldehyde emissions of medium density fiberboard

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3718-3733
Author(s):  
Osman Camlibel
Keyword(s):  
Liquid Paraffin ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Formaldehyde Emission ◽  
Modulus Of Rupture ◽  
Medium Density ◽  
Wood Fibers ◽  
Hot Press ◽  
Ammonium Sulphate Solution ◽  
Hot Press Process

Physical, mechanical, and formaldehyde emission properties were studied for medium density fiberboard (MDF) produced with oak (75%) and pine (25%) fibers that had been mechanically refined in the presence of calcite particles. The calcite slurry was prepared at two levels of solids, 1.5% and 3% (10 and 20 kg·m-³). Chips were cooked for 4 min at 185 °C, under 8 bar vapor pressure in an Andritz defibrillator. 1.8% liquid paraffin, 0.72% ammonium sulphate solution, and 11% urea-formaldehyde were added by percentage based on oven-dried wood fibers in the blowline at the exit of the defibrator. The fibers were dried to 11% moisture content. MDF boards (2100 mm × 2800 mm × 18 mm) were created using a continuous hot-press process. The addition of calcite in the course of MDF production resulted in improved physical properties, such as thickness swelling (ThS 24 hours) and water absorption (WA 24 hours). MDF boards prepared with calcite exhibited higher internal bond (IB), modulus of rupture (MOR), and modulus of elasticity (MOE). Resistance to axial withdrawal of screw also was increased by addition of 3% calcite. In addition, the lowest levels of formaldehyde emission were observed for MDF prepared with calcite at the 3% level.

scholarly journals Synthesis of Lignin-Based Polyacid Catalyst and Its Utilization to Improve Water Resistance of Urea–formaldehyde Resins

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 175 ◽  
Author(s):  
Shishuai Gao ◽  
Yupeng Liu ◽  
Chunpeng Wang ◽  
Fuxiang Chu ◽  
Feng Xu ◽  
...  
Keyword(s):  
Maleic Anhydride ◽  
13C Nmr ◽  
Water Resistance ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Formaldehyde Emission ◽  
Medium Density ◽  
1H And 13C Nmr ◽  
Uf Resin ◽  
Improve Water Resistance

In this study, a lignin-based polyacid catalyst was synthesized via two steps to enhance water resistance of urea–formaldehyde (UF) resins. The first steps involved a hydroxymethylation reaction to increase the hydroxyl content in lignin. Then, hydroxymethylated lignins were reacted with maleic anhydride to form maleated lignin-based polyacids. The acid groups were expected to function as acid catalysts to catalyze the curing process of UF resin. In order to elucidate the structural variation, 3-methoxy-4-hydroxyphenylpropane as a typical guaiacol lignin structural unit was used as a model compound to observe the hydroxymethylation and the reaction with maleic anhydride analyzed by 1H and 13C NMR. After the structural analysis of synthesized lignin-based polyacid by FTIR and 13C NMR, it was used to produce UF resin as an adhesive in plywood and medium density fiberboard (MDF) production, respectively. The results showed that when the addition of lignin-based polyacid was 5% in plywood, it could effectively improve the water resistance of UF resins as compared to commercial additive NH4Cl. It also exhibited a lower formaldehyde emission. Like plywood, lignin-based catalysts used in medium density fiberboard production could not only maintain the mechanical properties, but also inhibit the water adsorption of fiberboards.

Thermal Behavior Analysis of Melamine Modified Urea-Formaldehyde Resin with Different Molar Ratios

2020 ◽  
Vol 1001 ◽  
pp. 61-66
Author(s):  
Shan Feng Xu ◽  
San Shan Xia ◽  
Yu Zhu Chen ◽  
Hui Xiao ◽  
Ming Wei Jing ◽  
...  
Keyword(s):  
Activation Energy ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Urea Formaldehyde Resin ◽  
Molar Ratio ◽  
Formaldehyde Resin ◽  
Molar Ratios ◽  
High Molar Ratio ◽  
Degradation Properties ◽  
Modified Urea

In this study, Thermogravimetry (TG) were used to analyze thermal degradation properties of two kinds of low-molar ratio of the melamine-modified urea-formaldehyde resin (MUF). The MUF was calculated using Kissinger equation and Flynn-Wall-Ozawa equation Resin pyrolysis activation energy. The results showed that the curing time of low mole was longer than that of MUF resin (muf-b), the content of free formaldehyde was lower, and the formaldehyde emission and wet bonding strength of plywood were reduced by 65.79% and 21.90%, respectively. TG test showed that the pyrolysis process of MUF resins with different molar ratios can be divided into three stages: dehydration, rapid pyrolysis and carbonization. At the same heating rate, the weight loss rate, peak conversion rate and carbon residue of the high molar ratio MUF resin (MUF-a) in the fast pyrolysis stage are larger than those of the MUF-b resin. The MUF-a resin pyrolysis activation energy is 166.76 kJ/mol, and the MUF-b resin pyrolysis activation energy is 95.30 kJ/mol. High molar ratio resin has higher pyrolysis activation energy and better thermal stability.

Preparation of Water-Resistance Plywood with UF Resin Modified by Emulsifiable Polyisocyanate

2010 ◽  
Vol 26-28 ◽  
pp. 1056-1060
Author(s):  
Li Bin Zhu ◽  
Bo Han ◽  
Ji You Gu ◽  
Yan Hua Zhang ◽  
Hai Yan Tan ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Water Resistance ◽  
Urea Formaldehyde ◽  
Great Influence ◽  
Physical And Mechanical Properties ◽  
Formaldehyde Emission ◽  
Molar Ratio ◽  
Formaldehyde Resin ◽  
X Ray ◽  
Uf Resin

The purpose of the study was to manufacture water-resistance plywood with using UF resin modified by emulsifiable polyisocyanate. The emulsifiable polyisocyanate which contains plenty of hydrophilic segments and teminal isocyanate groups were synthesized by reaction between various kinds of polyether polyols and polymeric methane dipthenyl diisocyanate (pMDI). A type of composite adhesive was obtained from the mixture of emulsifiable polyisocyanate and urea formaldehyde resin. The process parameters, such as the molar ratio of –NCO and –OH, mass fraction of emulsifiable polyisocyanate in UF resin and accessory ingredient have a great influence on the composite adhesive. X-ray photoelectron spectroscopy (XPS) had been used to analyze the chemical structure of bonding interface. The results showed that the composite adhesive consisting of UF resin and emulsifiable polyisocyanate content of 7.5% and kaolin content of 1.5% was used in plywood with high physical and mechanical properties, water resistance and low formaldehyde emission.

scholarly journals Effect of Alumina Nano-Particles on Physical and Mechanical Properties of Medium Density Fiberboard

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4207 ◽  
Author(s):  
Hisham Alabduljabbar ◽  
Rayed Alyousef ◽  
Waheed Gul ◽  
Syed Riaz Akbar Shah ◽  
Afzal Khan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Thermo Gravimetric Analysis ◽  
Physical And Mechanical Properties ◽  
Nano Particles ◽  
Modulus Of Rupture ◽  
Alumina Nanoparticles ◽  
Gravimetric Analysis ◽  
Medium Density

This research aims to explore the effects of nanoparticles such as alumina (Al2O3) on the physical and mechanical properties of medium density fiberboards (MDF). The nanoparticles are added in urea-formaldehyde (UF) resin with different concentration levels e.g., 1.5%, 3%, and 4.5% by weight. A combination of forest fibers such as Populus Deltuidess (Poplar) and Euamericana (Ghaz) are used as a composite reinforcement due to their exceptional abrasion confrontation as well as their affordability and economic value with Al2O3-UF as a matrix or nanofillers for making the desired nanocomposite specimens. Thermo-gravimetric analysis (TGA) and thermal analytical analysis (TAA) in the form of differential scanning calorimetry (DSC) are carried out and it has been found that increasing the percentage of alumina nanoparticles leads to an increase in the total heat content. The mechanical properties such as internal bonding (IB), modulus of elasticity (MOE) and modulus of rupture (MOR), and physical properties such as density, water absorption (WA), and thickness swelling (TS) of the specimens have been investigated. The experimental results showed that properties of the new Nano-MDF are higher when compared to the normal samples. The results also showed that increasing the concentration of alumina nanoparticles in the urea-formaldehyde resin effects the mechanical properties of panels considerably.

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