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 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 Investigation of the Impact of Micro-Structuring on the Bonding Performance of Beechwood (Fagus Sylvatica L.)

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 113
Author(s):  
Destin Bamokina Moanda ◽  
Martin Lehmann ◽  
Peter Niemz
Keyword(s):  
Bond Strength ◽  
Waiting Time ◽  
Type I ◽  
Bond Quality ◽  
Structured Surfaces ◽  
Structured Surface ◽  
Bonding Performance ◽  
Delamination Resistance ◽  
Micro Structuring ◽  
The Impact

Although glueing softwood is well mastered by the industry, predicting and controlling bond quality for hardwood is still challenging after years of research. Parameters such as the adhesive type, resin–hardener ratio, and the penetration behaviour of the wood are determinants for the bond quality. The aim of this work was to assess to what extent the glueing behaviour of beechwood can be improved by using structural planing. The different surfacing methods were characterised by their roughness. The bond strength of the micro-structured surfaces was determined according to EN 302-1, and the delamination resistance was tested as indicated by EN 302-2 for type I adhesives. Micro-structured surfaces were compared with different surfaces (generated by surfacing methods such as dull/sharp planing and sanding). In dry test conditions, all surfacing methods gave satisfying results. In the wet stage, the bond strength on the finer micro-structured surface slightly outperformed the coarse structure surface. For the delamination resistance, a clear improvement could be observed for melamine-formaldehyde-bonded specimens since, when using the recommended amount of adhesive, micro-structured surfaces fulfilled the requirements. Nevertheless, structural planing cannot lead to a reduction in the applied grammage since no sample with a smaller amount fulfilled EN 302-2 requirements even by observing the recommended closed assembly waiting time. Adhesion area enlargement of the micro-structuring is minor. The good delamination performance without waiting time (CAT) is not caused by surface enlargement, since finer micro-structured surface with negligible area increase and delivered even better delamination resistance. Subsurface analysis should be carried out to thoroughly investigate this phenomenon.

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.

Labile Extractable Urea-Formaldehyde Resin Components from Medium-Density Fiberboard*

2015 ◽  
Vol 65 (1-2) ◽  
pp. 15-19 ◽  
Author(s):  
Warren J. Grigsby ◽  
James E. P. Carpenter ◽  
Armin Thumm ◽  
Rosie Sargent ◽  
Nancy Hati
Keyword(s):  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Urea Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Medium Density

scholarly journals Impact of malocclusion on the quality of life of Saudi children

2013 ◽  
Vol 83 (6) ◽  
pp. 1043-1048 ◽  
Author(s):  
Irfan Dawoodbhoy ◽  
Elsa K. Delgado-Angulo ◽  
Eduardo Bernabé
Keyword(s):  
Quality Of Life ◽  
Saudi Arabia ◽  
Multivariate Analysis ◽  
The Other ◽  
Arabic Version ◽  
Child Perception ◽  
Clinical Measures ◽  
The Impact ◽  
The Relationship

ABSTRACT Objective: To assess the relationship between malocclusion severity and quality of life in children. Materials and Method: Two hundred and seventy-eight children aged 11 to 14 years were recruited voluntarily from the Dental and Maxillofacial Centre of the Almana General Hospital in Alkhobar, Saudi Arabia. The children were asked to fill out the Arabic version of the Child Perception Questionnaire for 11- to 14-year-old children (CPQ11–14) and were then clinically examined to determine the severity of their malocclusion using the Dental Aesthetic Index (DAI). Multivariate analysis of variance was used to compare the four domains and the total CPQ11–14 scores between the four DAI severity groups. Results: Significant differences were found between DAI severity groups for the four domains and the total CPQ11–14 scores. Although children with very severe (handicapping) malocclusion had significantly higher domain and total CPQ11–14 scores than all the other groups (differences of up to 6 and 22 units, respectively, compared to children with no/minor malocclusion), there were no differences between those with no/minor, definite, and severe malocclusion. Conclusion: These findings suggest that only very severe malocclusion had an impact on the quality of life of the participants. Orthodontists should focus not only on clinical measures of malocclusion but should also consider the impact of severe malocclusion on patients' quality of life.

scholarly journals SHORT NOTES: APPLICATION OF MINERAL FILLER IN MEDIUM DENSITY FIBERBOARD (MDF) AND ITS EFFECT ON MATERIAL PROPERTIES AS A FUNCTION OF PARTICLE SIZE

Wood Research ◽  
2021 ◽  
Vol 66 (5) ◽  
pp. 891-899
Author(s):  
TOMASZ OZYHAR
Keyword(s):  
Particle Size ◽  
Material Properties ◽  
Filler Content ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Strength Properties ◽  
Inorganic Filler ◽  
Formaldehyde Resin ◽  
Medium Density ◽  
Wood Fibers

The addition of inorganic filler material in medium density fiberboard (MDF) and the effect on material properties as a function of particle size was examined. Medium density fiberboard was manufactured in a laboratory scale environment to a target raw densityof 750 kgm-3. Wood fibers were replaced by using calcium carbonate at 3 and 10 wt.% using fillers with weighted median particle sizes of d50= 2.0 μm and d50= 30 μm, respectively. Urea formaldehyde resin was used as binder in all MDF. The influence of filler addition on the modulus of elasticity, bending and tensile strength, dimensional stability and liquid permeability was investigated. The results demonstrate the effect of filler content and its dependence on particle size. The addition of filler with d50= 30 μm does not have any influence on material properties up to a filler content of 10 wt.%. Using the finer filler with d50= 2.0 μm at 10 wt.% filler, the quantity significantly increases the water adsorption and swelling behavior and reduces the strength properties of the MDF.

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