scholarly journals Potential Use of Wollastonite as a Filler in UF Resin Based Medium-Density Fiberboard (MDF)

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1435 ◽  
Author(s):  
Hamid R. Taghiyari ◽  
Ayoub Esmailpour ◽  
Roya Majidi ◽  
Jeffrey J. Morrell ◽  
Mohammad Mallaki ◽  
...  
Keyword(s):  
Bond Strength ◽  
Internal Bond ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Medium Density ◽  
Environmental Footprint ◽  
Positive Effects ◽  
Uf Resin ◽  
Resin Curing ◽  
Potential Use

Urea-formaldehyde (UF) resins are primary petroleum-based, increasing their potential environmental footprint. Identifying additives to reduce the total amount of resin needed without adversely affecting the panel properties could reduce these impacts. Wollastonite is a mineral containing calcium and silica that has been used as an additive in a variety of materials and may be useful as a resin extender. Nanoscale wollastonite has been shown to enhance the panel properties but is costly. Micron-scale wollastonite may be a less costly alternative. Medium-density fiberboards were produced by blending a hardwood furnish with UF alone, micron-sized wollastonite alone, or a 9:1 ratio of UF to wollastonite. Panels containing of only wollastonite had poor properties, but the properties of panels with 9:1 UF/wollastonite were similar to the UF-alone panels, except for the internal bond strength. The results suggest that small amounts of micron-sized wollastonite could serve as a resin extender. Further studies are suggested to determine if the micron-sized material has similar positive effects on the resin curing rate.

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

RSC Advances ◽  
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.

scholarly journals Some advantages of three-layer medium-density fibreboard as compared to the traditional single-layer one

2019 ◽  
Vol 65 (1) ◽  
Author(s):  
Turgay Akbulut ◽  
Nadir Ayrilmis
Keyword(s):  
Bond Strength ◽  
Internal Bond ◽  
Single Layer ◽  
Middle Layer ◽  
Resin Content ◽  
Internal Bond Strength ◽  
Medium Density ◽  
Medium Density Fibreboard ◽  
Uf Resin ◽  
Layer Medium

Abstract The aim of the study was to develop three-layer medium-density fibreboard (MDF) manufacture by adding the coarse fibres in the middle layer, like three-layer particleboard. The liquid urea–formaldehyde (UF) resin was reduced from 10.5 to 6.5 wt% in the middle layer of the MDFs. The UF resin content was kept constant at 10 wt% in the surface layers of all the MDFs. Moreover, the average density of MDFs was decreased from 730 to 650 kg/m3. The internal bond strength of three-layer MDFs decreased with decreasing UF resin content (10.5 to 8.5 wt%) in the middle layer. However, the decreases in the internal bond strength were statistically not significant. The internal bond strength values of the MDFs having density between 730 and 675 kg/m3 did not show significant differences. The cost savings of the resin were 20% when the amount of resin was reduced from 10.5 to 8.5 wt%. Three-layer MDFs had lower resin consumption at lower densities over traditional single-layer MDFs produced in the same plant with the same material components without decreasing their technological properties. In conclusion, it can be said that three-layer MDF could be produced at a lower cost than traditional single-layer MDF.

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.

Impact of pressing regime and substrate type on bond quality of decorative veneer

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2668-2679
Author(s):  
Vladislav Zdravković ◽  
Tanja Palija ◽  
Aleksandar Lovrić ◽  
Anđela Obradović
Keyword(s):  
Multivariate Analysis ◽  
Bond Strength ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Medium Density ◽  
Substrate Type ◽  
Bond Quality ◽  
The Impact ◽  
Moisture Resistant

The choice of optimal pressing regime for certain types of substrate is of great importance in production of veneered panels. In this paper, the impact of pressing regime on the bonding strength of beech and oak veneers, glued with urea-formaldehyde (UF) adhesive, on medium-density fiberboard (MDF), and moisture-resistant MDF (MR MDF) substrates was examined. The analyses showed a generally higher bond strength with oak veneer compared to beech veneer, which was also the case with regular MDF compared to moisture-resistant MDF. Multivariate analysis of variance (ANOVA) showed that with beech veneer, all of the used regimes produced better results on regular MDF compared to moisture-resistant MDF. In contrast, with oak veneer, the influence of pressing regime had a more noteworthy impact than the type of substrate used. These results indicated that the use of MR MDF as substrate in combination with UF adhesive was inadequate.

scholarly journals Effect of Panel Moisture Content on Internal Bond Strength and Thickness Swelling of Medium Density Fiberboard

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 114
Author(s):  
Roberto Magalhães ◽  
Beatriz Nogueira ◽  
Samaritana Costa ◽  
Nádia Paiva ◽  
João M. Ferra ◽  
...  
Keyword(s):  
Moisture Content ◽  
Bond Strength ◽  
Internal Bond ◽  
Room Temperature ◽  
Medium Density Fiberboard ◽  
Internal Bond Strength ◽  
Medium Density ◽  
Thickness Swelling ◽  
European Standard ◽  
Test Pieces

Wood-based products usually have serious limitations concerning contact with water, both because wood is a hygroscopic material and because the commonly used binder has low moisture resistance. This paper studies the effect of panel moisture content (MC) on the physico-mechanical properties of medium density fiberboards (MDF). Several commercial MDF boards produced in Europe were stored at room temperature and relative humidity (RH) for 9 weeks (approx. range 15–20 °C and 50–85% RH). Every week, a strip of each MDF board was cut out, divided into 5 × 5 cm test pieces and its internal bond strength (IB) was measured. A strong influence of MDF moisture content on internal bond strength was observed and therefore IB test pieces were stored in a climatic chamber (either at 20 °C, 55% RH and at 20 °C, 70% RH). A decreasing linear relation was established between IB and MC. It was found that this effect is reversible: after drying, internal bond strength rises again (following a slight hysteresis). This work reinforces the importance of conditioned storage before board properties analysis, as described in European Standard EN 319.

Preparation and Characteristic of Urea Formaldehyde Modified with Hexamethoxymethyl Melamine

2010 ◽  
Vol 160-162 ◽  
pp. 1245-1252
Author(s):  
Zhen Zhong Gao ◽  
Li Tao Guan ◽  
Jin Sun ◽  
Deng Yun Tu
Keyword(s):  
Bond Strength ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Solidification Time ◽  
Uf Resin ◽  
Optimum Formulation ◽  
Chinese Standard

Hexamethoxymethyl melamine (HMMM) was used to modify UF resins to obtain good performance with low formaldehyde emission. The effect of urea to formaldehyde ratio, HMMM content on the properties of UF resin was studied in detail. The results suggested that urea to formaldehyde ratio to be 1:0.9 and 20% HMMM content is the optimum formulation to afford desired UF resin. The viscosity, solidification time, bond strength and formaldehyde emission of the modified UF resins were also studied. The results revealed that the performance of the modified UF achieved the chinese standard.

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