scholarly journals Experimental Investigation of Vertical Density Profile of Medium Density Fiberboard in Hot Press

2021 ◽  
Vol 11 (22) ◽  
pp. 10769
Author(s):  
Asfar Hameed Minhas ◽  
Naveed Ullah ◽  
Asim Ahmad Riaz ◽  
Muftooh Ur Rehman Siddiqi ◽  
Khamael M. Abualnaja ◽  
...  
Keyword(s):  
Moisture Content ◽  
Density Profile ◽  
Cycle Time ◽  
Medium Density Fiberboard ◽  
Medium Density ◽  
Internal Bonding ◽  
Hot Press ◽  
Vertical Density Profile ◽  
Pressure Cycle ◽  
Vertical Density

This research investigates the performance of medium density fiberboard (MDF) with respect to hot press parameters. The performance of the board, type of glue, and production efficiency determine the optimum temperature and pressure for hot pressing. The actual temperature of the hot press inside the MDF board determines the properties of the final product. Hence, the optimal hot press parameters for the desired product are experimentally obtained. Moreover, MDF is experimentally investigated in terms of its vertical density profile, bending, and internal bonding under the various input parameters of temperature, pressure, cycle time, and moisture content during the manufacturing process. The experimental study is carried out by varying the temperature, pressure, cycle time, and moisture content in the ranges of 200–220 °C, 145–155 bar, 260–275 s, and 8–10%, respectively. Consequently, the optimum input parameters of a hot-pressing temperature of 220 °C, pressure of 155 bar, cycle time of 256 s, and moisture content of 8% are identified for the required internal bonding (0.64 N/mm2), bending (32 N/mm2), and increase in both the core and peak density of the vertical density profile as per the ASTM standard.

Modelling of the Development of the Vertical Density Profile of MDF during Hot Pressing

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
Arun Gupta ◽  
Patrick Jordan ◽  
Shusheng Pang
Keyword(s):  
Moisture Content ◽  
Density Profile ◽  
Hot Pressing ◽  
Major Influence ◽  
Transfer Model ◽  
Uniform Density ◽  
Moisture Movement ◽  
Vertical Density Profile ◽  
Vertical Density ◽  
Pressing Operation

The hot pressing operation is one of the most important operations in medium density fibreboard (MDF) manufacture. Complicated dynamic interactions occur during pressing, including heat transfer, moisture movement, development of gas pressure, internal stress development and relaxation, wood consolidation, resin curing, bonding between particles and eventual development of a non-uniform density distribution through the panel thickness. Consequently the mat experiences continuously changing internal conditions (temperature and moisture content) as the pressing operation proceeds. The vertical density profile (VDP) has a major influence on the MDF strength and physical properties. This influence of the VDP on the board properties is generally recognised, but the formation of the density profile and their specific effects on the board performance have proved difficult to quantify. A mathematical model based on theoretical analysis and experimental information is being developed. In the model, the mat is divided into a number of thin parallel layers. The deformation of each layer is a function of stress, temperature and moisture content of the layer. The model incorporates the variation of the mat mechanical and rheological properties with moisture content and temperature. The changes in temperature and moisture content are provided by a separate heat and mass transfer model. The present model can predict stress, strain, layer deformation and density across the thickness during pressing. The performance of the model was validated by experiments conducted in a pilot-scale press. Twelve MDF boards were made with different pressing parameters, and the VDP were measured and compared with the simulation results from the model. The model could predict the density profile with an acceptable accuracy for the main variables that control the manufacturing of MDF boards.

Poisson’s ratio of the MDF in respect to vertical density profile

2014 ◽  
Vol 72 (3) ◽  
pp. 407-410 ◽  
Author(s):  
Václav Sebera ◽  
Jan Tippner ◽  
Milan Šimek ◽  
Jan Šrajer ◽  
David Děcký ◽  
...  
Keyword(s):  
Density Profile ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Vertical Density Profile ◽  
Vertical Density

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 PAG Concentration Dependence of the Vertical Density Profile in Photoresist

2010 ◽  
Vol 23 (5) ◽  
pp. 709-713 ◽  
Author(s):  
Jae Hyun Kim ◽  
Sung II Ahn ◽  
Yong-ho Kim ◽  
Jin Goo Yoon ◽  
Wang-Cheol Zin ◽  
...  
Keyword(s):  
Concentration Dependence ◽  
Density Profile ◽  
Vertical Density Profile ◽  
Vertical Density

Simple production of medium density fiberboards (MDF) reinforced with chitosan

Holzforschung ◽  
2018 ◽  
Vol 72 (4) ◽  
pp. 275-281 ◽  
Author(s):  
Xiaodi Ji ◽  
Yue Dong ◽  
Ruidong Yu ◽  
Wenxin Du ◽  
Xue Gu ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Photoelectron Spectroscopy ◽  
Medium Density Fiberboard ◽  
National Standard ◽  
Medium Density ◽  
Wood Fibers ◽  
Hot Press ◽  
X Ray ◽  
Amide Bonds ◽  
Simple Production

AbstractA simple and efficient method was developed for preparing medium density fiberboard (MDF) reinforced with chitosan via the traditional hot-press manufacturing process. The mechanical and dimensional properties of the MDF were investigated as a function of the chitosan amount. At the 4% level of added chitosan, the MDF reached the optimal performance and met completely the requirements of the Chinese national standard GB/T 11718-2009. Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD) characterizations revealed that wood fibers and chitosan might interact with each other through the formation of hydrogen and amide bonds during the hot-pressing process. The fracture surfaces of the MDFs are indicative for strong bonds at the interface, which explain the excellent MDF performance.

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