Microwave-assisted laminated veneer lumber (LVL): Investigation on the effect of preheating time and moisture content on resin penetration and bonding quality

Utilisation of forest plantation species such as Acacia hybrid has been used in wood-based industry as an alternative to solid wood that was usually attained from natural forest. While, the under-utilised species such as Mangifera sp. is not often been used as raw material for wood products, in this study, laminated veneer lumber (LVL) has been produced from Acacia hybrid and Mangifera sp. The physical and mechanical properties of LVL were determined and compared. For physical testing, the range value of moisture content was 9.41% to 14.56%, Density was 487.90 kg/m3 to 699.10 kg/m3, thickness swelling was between 0.20% to 6.05%, water absorption between 32.71% to 91.25%, and rate of delamination from 0% to 100%. Mangifera sp. LVL has higher moisture content, rate of delamination, and water absorbency. In mechanical testing, it is been found that Acacia hybrid LVL has overall higher strength compared to Mangifera sp. LVL, in terms of static bending strength (MOR and MOE), shear strength, and compression strength. Range of value for MOR was between 10.27 N/mm2 to 129.99 N/mm2, MOE between 1138 N/mm2 to 16472.93 N/mm2, shear strength between 0.43 N/mm2 to 3.40 N/mm2, and compression between 139.45 N/mm2 to 6749.74 N/mm2. For physical testing, the overall result of p-value for moisture content, water absorption, and delamination were significant at p ≤ 0.05, while density and thickness swelling were not significant at p ≥ 0.05. For overall result, the p-value for static bending strength (MOR and MOE) was significant at p ≤ 0.05 while for shear strength and compression strength were not significant at p ≥ 0.05.

Download Full-text

Microwave Assisted Vacuum Drying and Endpoint Determination Using Mass Spectrometry, Part II, On-Line Moisture Content Profiling

Organic Process Research & Development ◽

10.1021/op049853s ◽

2004 ◽

Vol 8 (6) ◽

pp. 867-872 ◽

Cited By ~ 3

Author(s):

Kevin Hettenbach ◽

David J. am Ende ◽

Eric Dias ◽

Steven J. Brenek ◽

Catherine Laforte ◽

...

Keyword(s):

Mass Spectrometry ◽

Moisture Content ◽

Vacuum Drying ◽

Microwave Assisted ◽

On Line

Download Full-text

Prediction of plywood bonding quality using an artificial neural network

Holzforschung ◽

10.1515/hf.2011.003 ◽

2011 ◽

Vol 65 (2) ◽

Cited By ~ 15

Author(s):

Luis García Esteban ◽

Francisco García Fernández ◽

Paloma de Palacios

Keyword(s):

Neural Network ◽

Artificial Neural Network ◽

Moisture Content ◽

Input Data ◽

Bending Strength ◽

Testing Time ◽

Bonding Quality ◽

Time Problem ◽

Artificial Neural ◽

Test Result

Abstract The bonding quality test is one of the most important of all tests performed on plywood, because it determines the suitability of boards for use in the type of exposure they are intended for. Because this test involves aging pretreatment, results are not available in <24–97 h after manufacture, depending on the type of board, and therefore any error in the manufacturing process is not detected until 1–4 days later. To solve this time problem, an artificial neural network was developed as a predictive method to determine the suitability of board bonding through other properties that can be determined in less testing time: thickness, moisture content, density, bending strength, and modulus of elasticity. The network designed WAS a feedforward multilayer perceptron trained by supervised learning after normalization of the input data, and allowed the bonding test result to be predicted with 93% accuracy.

Download Full-text

Calibration of Electrical Resistance to Moisture Content for Beech Laminated Veneer Lumber “BauBuche S” and “BauBuche Q”

Forests ◽

10.3390/f12050635 ◽

2021 ◽

Vol 12 (5) ◽

pp. 635

Author(s):

Philippe Grönquist ◽

Gianna Weibel ◽

Claude Leyder ◽

Andrea Frangi

Keyword(s):

Moisture Content ◽

Electrical Resistance ◽

High Performance ◽

Beech Wood ◽

Gravimetric Method ◽

Model Parameters ◽

Data Set ◽

Laminated Veneer Lumber ◽

Calibration Models ◽

Different Depths

Electrical resistance measurements are often employed for the purpose of nondestructive long-term monitoring of wood moisture content (MC) in timber structures. As a structural material for high-performance load-bearing applications in such structures, beech laminated veneer lumber (LVL) enjoys a growing popularity. However, due to the processing of beech LVL affecting physical properties, calibration curves for bulk beech wood cannot be used. In this study, resistance was measured on 160 beech LVL samples equilibrated in four different relative humidity (RH) climates. The results show a difference not only between the beech LVL products “BauBuche S” and “BauBuche Q”, but also between measurements at two different depths. For each data set, parameters for calibration models using two and using three model parameters were determined by regression analysis to MC determined by the gravimetric method.

Download Full-text

Physical properties and bonding quality of laminated veneer lumber produced with veneers peeled from small-diameter rubberwood logs

Royal Society Open Science ◽

10.1098/rsos.191763 ◽

2019 ◽

Vol 6 (12) ◽

pp. 191763 ◽

Cited By ~ 1

Author(s):

P. S. Khoo ◽

K. L. Chin ◽

P. S. H'ng ◽

E. S. Bakar ◽

C. L. Lee ◽

...

Keyword(s):

Phenol Formaldehyde ◽

Small Diameter ◽

Lower Grade ◽

Bonding Quality ◽

Laminated Veneer Lumber ◽

Short Rotation ◽

Different Temperatures ◽

Lamination Process ◽

Lathe Check

The peeling of small-diameter rubberwood logs from the current short-rotation practices undoubtedly will produce lower grade veneers compared to the veneers from conventional planting rotation. Hence, this raises the question of the properties of the produced laminated veneer lumber (LVL) from veneers peeled from small-diameter rubberwood logs using the spindleless lathe technology. Different thicknesses of rubberwood veneers was peeled from rubberwood logs with diameter less than 20 cm using a spindleless lathe. Three-layer LVLs were prepared using phenol formaldehyde (PF) adhesive and hot pressed at different temperatures. During the peeling of veneer, lathe checks as deep as 30–60% of the veneer thickness are formed. Owing to deeper lathe check on 3 mm rubberwood veneer, higher pressing temperature significantly increased the gluebond shear strength of the PF-bonded LVL. In addition, lathe check frequency was also shown to influence the bond strength. The presence of higher lathe check frequency on 2 mm veneer increased the wettability, thus facilitating optimum penetration of adhesive for stronger bonding. These findings stress the importance of measuring and considering the lathe check depth and frequency during the lamination process to get a better understanding of bonding quality in veneer-based products.

Download Full-text

The effects of the moisture content of laminated veneer lumber on bending strength and deformation determination via two-dimensional digital image correlation

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220986181 ◽

2021 ◽

pp. 095440622098618

Author(s):

Eser Sözen ◽

Kadir Kayahan ◽

Timuçin Bardak ◽

Selahattin Bardak

Keyword(s):

Digital Image Correlation ◽

Moisture Content ◽

Digital Image ◽

Bending Strength ◽

Image Correlation ◽

Bending Test ◽

Homogeneous Distribution ◽

Two Dimensional ◽

Laminated Veneer Lumber ◽

Strength And Deformation

This study determined the bending strength values of laminated veneer lumber (LVL) made with beech ( Fagus orientalis L.) veneer obtained by the peeling process and having four different moisture content values (0%/oven dry, 12%, 18%, and 25%). Bending tests were carried out in two different ways, i.e., for the flatwise and edgewise aspects of the LVL. Strain maps were created using two-dimensional digital image correlation (2 D DIC) and the samples having different moisture contents were compared. At the same time, the amount of displacement of the samples during the bending test was determined via conventional and DIC methods. Results of the study determined that the moisture content was effective in bending strength and tension zones. It was observed that increasing moisture content created homogeneous distribution of deformation. It was also observed that the data obtained by the 2 D DIC method were compatible with those obtained by the conventional method.

Download Full-text

Calibration and comparison of two moisture content measurement methods for in situ monitoring of beech laminated veneer lumber

Wood Material Science and Engineering ◽

10.1080/17480272.2021.1958918 ◽

2021 ◽

pp. 1-12

Author(s):

Marcus Schiere ◽

Bettina Franke ◽

Steffen Franke ◽

Andreas Müller

Keyword(s):

Moisture Content ◽

Measurement Methods ◽

In Situ Monitoring ◽

Laminated Veneer Lumber ◽

Content Measurement ◽

Moisture Content Measurement

Download Full-text

Geopolymer-Bonded Laminated Veneer Lumber as Environmentally Friendly and Formaldehyde-Free Product: Effect of Various Additives on Geopolymer Binder Features

Applied Sciences ◽

10.3390/app10020593 ◽

2020 ◽

Vol 10 (2) ◽

pp. 593 ◽

Cited By ~ 1

Author(s):

Ali Shalbafan ◽

Heiko Thoemen

Keyword(s):

Mechanical Properties ◽

Silica Fume ◽

Positive Impact ◽

Environmentally Friendly ◽

Gel Time ◽

Scanning Calorimetry ◽

Bonding Quality ◽

Laminated Veneer Lumber ◽

Geopolymer Binder ◽

Shear Bending

Environmentally friendly and formaldehyde-free laminated veneer lumber (LVL) was manufactured using geopolymer constituents as binder. The main aim of the study was to improve the bonding quality between the geopolymer binder and the wood constituents. To this end, the effect of various additives (phenol flakes, conventional silica fume, and grafted silica fume with 3-aminopropyltriethoxysilane (APTES)) in the geopolymer binder features were explored via gel time and viscosity measurements, differential scanning calorimetry (DSC), and Fourier transom infrared spectroscopy. The mechanical properties (shear, bending, and compression) of LVL panels were also determined. Results showed that adding both types of silica fume had a positive impact on the geopolymer binder features. The formation of an alkaline aluminosilicate network was proven by observing the characteristics peaks of geopolymer binder at about 683 and 970 cm−1. A peak temperature of about 98 °C was determined for the geopolymer binder curing via DSC analysis. The mechanical properties were the highest for LVL panels made of geopolymer binder with grafted silica fume. It is feasible that the APTES used as grafting agent created a better bonding mechanism with superficial wood cells. In summary, the produced LVL panel showed good properties, but it still needs to be further improved to reach the required levels for use in interior and humid application.

Download Full-text