Monitoring Resin Cure Of Medium Density Fiberboard Using Dielectric Sensors

1996 ◽  
Vol 430 ◽  
Author(s):  
R. J. King ◽  
R. W. Rice
Keyword(s):  
Dielectric Constant ◽  
Real Time ◽  
Wood Density ◽  
Complex Permittivity ◽  
Loss Factor ◽  
Phenol Formaldehyde ◽  
Medium Density Fiberboard ◽  
Modulus Of Rupture ◽  
Curing Process ◽  
Medium Density

AbstractFlush mounted, in-press microwave (600–800 MHz) sensors have been developed for monitoring the complex permittivity in real time during the cure of medium density fiberboard. The measured dielectric constant (ε')a nd loss factor (ε") are independent diagnostic indicators of dynamic cure events that are catalyzed by heat, pressure and moisture. In particular, with this technique the instantaneous effects of resin viscosity, rate and degree of adhesive cure, the wood density, the changes in phase of the moisture and the rate of moisture depletion can be monitored during the entire curing process.The comparative roles of moisture and adhesive content are discussed, along with the comparative modulus of rupture with cure duration. Results are presented comparing the dynamics of phenol-formaldehyde and isocyanate resins.

scholarly journals The Effects of SLS on Structural and Complex Permittivity of SLS-HDPE Composites

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Abubakar Dantani Meli ◽  
Zulkifly Abbas ◽  
Mohd Hafiz Mohd Zaid ◽  
Nor Azowa Ibrahim
Keyword(s):  
Dielectric Constant ◽  
Complex Permittivity ◽  
Loss Factor ◽  
Microwave Frequency ◽  
Soda Lime ◽  
Physical Structure ◽  
Host Matrix ◽  
Lower Dielectric Constant ◽  
Absorbing Material ◽  
Diffraction Patterns

RS-4050 is a rigid epoxy based magnetic castable microwave absorbing material; it has been used in many areas of waveguide application as a microwave waveguide terminations and dummy loads. In recent years, there is a demand for composites material with lower dielectric constant higher loss factor for microwave application. This research, the effect of soda lime silica (SLS) on structural and complex permittivity of soda lime silica-high density polyethylene (SLS-HDPE) composites was conducted in order to explore the possibility of substituting RS-4050 with SLS-HDPE composites as a microwave waveguide terminations and dummy loads. Elemental weight composition of the SLS glass powder and HDPE was identified through scaling of different percentage of SLS and HDPE. X-ray diffraction (XRD) was used to investigate the crystallinity behavior of SLS-HDPE composites. The proposed SLS-HDPE composites material was studied at frequencies 8 to 12 GHz. The study was conducted using waveguide Agilent N5230A PNA technique. The effect of microwave frequency on complex permittivity properties for SLS-HDPE composites of different percentages of SLS and HDPE (10% SLS-90% HDPE, 20% SLS-80% HDPE, 30% SLS-70% HDPE, 40% SLS-60% HDPE, and 50% SLS-50% HDPE) were investigated. Results showed the diffraction patterns reveal good amorphous quality with a genuinely properties structure. The microwave frequency and composites percentages significantly influenced the complex permittivity (real and imaginary) properties of the composites. Moreover, the complex permittivity increased as the percentage of SLS filler increased in the host matrix HDPE as a result of increased in composite density due to less volume being occupied by the filler as the percentage increased. The complex permittivity of the smallest and largest percentages of SLS (10% and 50%) was (2.67-j0.05) and (3.45-j0.35), respectively. The study revealed that the best sample for waveguide application as microwave terminator is 50% SLS as it has the highest dielectric constant, highest loss factor, and highest loss tangent as compared to 10% SLS to 40% SLS. Also 50% SLS has the highest absorption properties as compare to 10% SLS, 20% SLS, 30% SLS, or 40% SLS. The XRD physical structure of the SLS-HDPE composites revealed the absorption characteristics of different percentages of the materials. The SLS-HDPE composites can be applied in the area of waveguide as a microwave waveguide terminations and dummy loads.

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.

Properties of thermally modified medium-density fibreboards

Holzforschung ◽  
2012 ◽  
Vol 66 (1) ◽  
Author(s):  
Jürgen Bonigut ◽  
Detlef Krug ◽  
Beate Stephani
Keyword(s):  
Thermal Treatment ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Phenol Formaldehyde ◽  
Creep Behaviour ◽  
Modulus Of Rupture ◽  
Medium Density ◽  
Thickness Swelling ◽  
Short Term ◽  
European Standards

Abstract Thermal treatment of solid timber and oriented strandboards (OSB) improves durability against fungal decay and dimensional stability (swelling and shrinking). It is not clear whether thermal treatment of medium-density fibreboards (MDF) has the same effects. In this work, four variants of phenol-formaldehyde (PF)-bonded MDF with varying contents of resin and hydrophobing agent were thermally post-treated according to the Mühlböck procedure at three different maxi-mum temperatures. The short-term properties internal bond, modulus of rupture, modulus of elasticity, thickness swelling and equilibrium moisture content and the long-term property creep behaviour of treated variants and of one untreated variant have been tested. The results are presented and discussed in comparison with the respective European standards. Altogether, the thermal treatment had a positive effect on most of the tested mechanical short-term properties. The moisture-related properties, i.e., thickness swelling and equilibrium moisture content, were also positively influenced. The creep behaviour of heat-treated MDF could also be improved by thermal modification.

Effect of juvenile wood on strength properties and dimensional stability of black spruce medium-density fiberboard panels

Holzforschung ◽  
2005 ◽  
Vol 59 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Jun Li Shi ◽  
Shu Yin Zhang ◽  
Bernard Riedl
Keyword(s):  
Water Absorption ◽  
Dimensional Stability ◽  
Juvenile Wood ◽  
Black Spruce ◽  
Medium Density Fiberboard ◽  
Strength Properties ◽  
Analysis Of Covariance ◽  
Modulus Of Rupture ◽  
Medium Density ◽  
Mean Values

Abstract Strength properties and dimensional stability of medium-density fiberboard (MDF) panels made from black spruce (Picea mariana [Mill.] BSP.) 0–20, 21–40, and over 40 year old fiber were studied. An analysis of covariance (ANCOVA) was performed to examine the differences in modulus of rupture (MOR), modulus of elasticity (MOE), and thickness swell (TS) of the three types of panels, while panel density was treated as a covariate in order to adjust the mean values that were partly attributed to panel density. The results indicate that MOR, internal bond (IB), and water absorption of MDF panels made from 0–20 year old fiber, which contained 100% juvenile wood, were significantly superior to those of panels made from 21–40 and over 40 year old fiber; but linear expansion (LE) of MDF panels made from 0–20 year old fiber was significantly larger than that of panels from the other two age classes. The differences in MOR, IB, water absorption, and LE between panels made from 21–40 and over 40 year old fiber were not significant. The comparisons of panel MOE and TS were relatively dependent on panel density due to existence of interactions among the three age groups.

Multivariate modeling of MDF panel properties in relation to wood fiber characteristics

Holzforschung ◽  
2006 ◽  
Vol 60 (3) ◽  
pp. 285-293 ◽  
Author(s):  
Jun Li Shi ◽  
S.Y. Zhang ◽  
Bernard Riedl
Keyword(s):  
Wood Density ◽  
Medium Density Fiberboard ◽  
Wood Fiber ◽  
Arithmetic Mean ◽  
Modulus Of Rupture ◽  
Predictor Variables ◽  
Small Particles ◽  
Dummy Variables ◽  
Functional Relationships ◽  
Response Variables

Abstract Properties of medium density fiberboard (MDF) panels in relation to wood and fiber characteristics were investigated. Laboratory MDF panels were manufactured from raw fiber materials from black spruce [Picea mariana (Mill.) BSP.], three hybrid poplar clones (Populus spp.), two exotic larch (Larix gmelinii and Larix sibirica), and a mix of spruce, pine, and fir wood chips. The panels were evaluated for modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), linear expansion (LE), thickness swelling (TS), and water absorption (WA). These properties were analyzed as response variables. As predictor variables, various wood and fiber characteristics were measured, including wood density, pH, base buffering capacity and fiber coarseness. Multiple linear regression analysis was performed to develop functional relationships between panel properties (response variables) and wood fiber characteristics (predictor variables). Ten dummy variables were created and incorporated into the analysis to examine the effects of wood species or type on MDF panel properties. MOR was negatively related to arithmetic fine percentage. MOE was negatively affected by the percentage of small particles (>200 mesh) and wood pH. IB strength was negatively related to arithmetic fine percentage and fiber pH, but positively related to the percentage of small particles (>200 mesh). Wood density affected LE. TS was negatively affected by arithmetic mean fiber length. Arithmetic mean fiber width had a negative effect on panel WA. The presence of dummy variables in the models for MOE, IB and LE indicates that wood fiber characteristics other than those measured in this study significantly affected these panel properties. The study indicates that the refining process can play a significant role in manipulating MDF panel properties.

Effect of Incorporation of Flame Retardants on Some of the Properties of Phenol Formaldehyde Medium Density Fiberboard

2008 ◽  
Vol 3 (5) ◽  
pp. 331-339 ◽  
Author(s):  
O. Sulaiman ◽  
R. Hashim ◽  
R.N. Kumar ◽  
P. Tamyez ◽  
R.J. Murphy ◽  
...  
Keyword(s):  
Flame Retardants ◽  
Phenol Formaldehyde ◽  
Medium Density Fiberboard ◽  
Medium Density

Effect of Core Temperature on Some Important Properties of Poplar Scrimber Boards during the Heat Curing Process

2019 ◽  
Vol 69 (3) ◽  
pp. 210-216
Author(s):  
Fei Rao ◽  
Jinguang Wei ◽  
Yue Qi ◽  
Yahui Zhang ◽  
Wenji Yu
Keyword(s):  
Mechanical Properties ◽  
Core Temperature ◽  
Large Scale ◽  
Phenol Formaldehyde ◽  
Formaldehyde Emission ◽  
Modulus Of Rupture ◽  
Curing Process ◽  
Horizontal Shear ◽  
Heat Curing ◽  
Swelling Rate

Abstract In this study, poplar wood and a phenol-formaldehyde (PF) resin were used to produce a large-scale scrimber product by a combined cold pressing and heat curing method. The water resistance, mechanical properties, and formaldehyde emission of the scrimber boards prepared at different core temperatures (100°C, 110°C, 115°C, and 120°C) were investigated. The results showed that the peak core temperature had a significant effect on the scrimber performance. The thickness swelling rate and width swelling rate of the scrimber boards prepared at a core temperature of 100 °C were significantly higher than other samples. The formaldehyde emission from the surface layer of the scrimber boards prepared at a high core temperature (115°C and 120°C) was much lower than that at a core temperature of 100°C and 110°C. These results can be explained by the correlation between curing degree and temperature of the PF resin in the scrimber. With increasing core temperature, the modulus of rupture, compression strength, and horizontal shear strength of the scrimber boards first increased and then decreased, suggesting that core temperature during the heat curing process also played an important role in determining mechanical properties. The scrimber boards with the best mechanical properties were prepared at a core temperature of 115°C. The results of the study demonstrated that the optimal core temperature necessary to produce a low-cost and high-performance scrimber was 115°C.

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.

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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