scholarly journals Improved strength properties of LVL glued using PVAc adhesives with physical treatment-based Rubberwood (Hevea brasiliensis)

2020 ◽  
Vol 5 (1) ◽  
pp. 711-725
Author(s):  
Sutrisno ◽  
Eka Mulya Alamsyah ◽  
Ginanjar Gumilar ◽  
Takashi Tanaka ◽  
Masaaki Yamada
Keyword(s):  
Shear Strength ◽  
Hevea Brasiliensis ◽  
Formaldehyde Emission ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Horizontal Shear ◽  
Physical Treatment ◽  
Cold Pressing ◽  
Laminated Veneer Lumber ◽  
Pressing Time

AbstractThe properties of the laminated veneer lumber (LVL) composed of the boiled veneer of Rubberwood (Hevea brasiliensis) using polyvinyl acetate (PVAc) adhesives in various cold-pressing time and various conditioned time with loaded and unloaded were studied. Five-ply LVL was produced by boiling veneer at 100°C for 90 min as pretreatment and cold-pressing time at 12 kgf cm−2 for 1.5, 6, 18, and 24 h then conditioned at 20°C and 65% relative humidity (RH) with loaded (12 kgf cm−2) and unloaded for 7 days as physical treatment. Especially for the delamination test, the specimens were immersed at 70 ± 3°C for 2 h and dried in the oven at 60 ± 3°C for 24 h; then, the specimens were solidified at room temperature (20°C and 65% RH) with loaded (12 kgf cm−2) and unloaded for 7, 10, 12, and 14 days. To determine the performance of LVL, the density, moisture content (MC), delamination, modulus of elasticity (MOE), modulus of rupture (MOR), horizontal shear strength, and formaldehyde emission tests were conducted according to the Japanese Agricultural Standard (JAS 2008) for structural LVL. The MOE and MOR values were significantly influenced by the physical treatment, however, neither to horizontal shear strength nor to formaldehyde emission. The best performance of LVL has resulted from unloaded LVL with cold-pressed time for 18 h; the MOE and MOR values were 9,345.05 ± 141.61 N mm−2 and 80.67 ± 1.77 N mm−2, respectively. The best value of the horizontal shear strength was obtained from the LVL with 18 h cold-pressing time and conditioned with loaded (13.10 ± 1.47 N mm−2) and unloaded (12.23 ± 1.36 N mm−2). The percentage of delamination values decreased with an increase in the cold-pressing time and conditioning time. The lowest value of delamination (19.06%) was obtained from the LVL with 24 h cold-pressing time and conditioned with loaded for 14 days. Except the delamination test, all other properties fulfilled the JAS.

Study on the Technology and Properties of Soybean Adhesive Bonded Laminated Veneer Lumber from Poplar Wood

2012 ◽  
Vol 174-177 ◽  
pp. 847-851
Author(s):  
Wen Ding Li ◽  
Yang Zhang ◽  
Cong Liu ◽  
Kien Nguyentrong ◽  
Chong Jia
Keyword(s):  
Mechanical Properties ◽  
Hot Pressing ◽  
Modulus Of Rupture ◽  
Poplar Wood ◽  
Horizontal Shear ◽  
Pressing Temperature ◽  
Laminated Veneer Lumber ◽  
Pressing Time ◽  
Mechanical And Physical Properties ◽  
The Mean

It was investigated that the technology of hot prepressing temperature and hot pressing duration had influence on the mechanical and physical properties of soybean adhesive bonded laminated veneer lumber(LVL) from poplar wood. The results show that lower mat prepressing temperature may be beneficial to the mechanical properties of LVL. The effects of hot pressing duration on the properties of LVL are less than those of prepressing temperature. When the prepressing temperature is 70°C and hot pressing time is 100s/mm with glue spread amount of 450g/m2, hot pressing temperature of 160°C and mat pressure of 1.6 MPa, the mean modulus of rupture value is 78 MPa, mean modulus of elasticity value is 14.4 GPa, mean horizontal shear strength value is 7.8 MPa and immersion peel rate is 0.4%, respectively.

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.

Mechanical properties of Ficus vallis-choudae (Delile), a lesser utilized species in Nigeria

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 6550-6560
Author(s):  
Lawrence Aguda ◽  
Babatunde Ajayi ◽  
Sylvester Areghan ◽  
Yetunde Olayiwola ◽  
Aina Kehinde ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
High Strength ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Impact Bending ◽  
Timber Market

Declining availability of the prime economic species in the Nigerian timber market has led to the introduction of Lesser-Used Species (LUS) as alternatives. Their acceptability demands information on the technical properties of their wood. The aim of this study was to investigate the mechanical properties of Ficus vallis-choudae to determine its potential for timber. Three mature Ficus vallis-choudae trees were selected and harvested from a free forest area in Ibadan, Oyo State, Nigeria. Samples were collected from the base (10%), middle (50%), and top (90%) along the sampling heights of each tree, which was further partitioned into innerwood, centrewood, and outerwood across the sampling radial position. Investigations were carried out to determine the age, density, moisture content, impact strength, modulus of elasticity, modulus of rupture, compressive strength parallel-to-grain, and shear strength parallel-to-grain. The mean impact bending strength, modulus of rupture, modulus of elasticity, maximum shear strength parallel-to-grain, and maximum compression strength parallel-to-grain for Ficus vallis-choudae at 12% moisture content were 20.4 N/mm2, 85.8 N/mm2, 709 N/mm2, 10.7 N/mm2, and 33.6 N/mm2, respectively. The study found the species to be dense with high strength properties in comparison with well-known timbers used for constructional purposes.

Effect of Compression Ratio and Lay Angle of Metal Net on the Mechanical Properties of Metal Net-LVL Composite

2011 ◽  
Vol 418-420 ◽  
pp. 505-508
Author(s):  
Jin Li ◽  
Ying Cheng Hu
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Mechanical Strength ◽  
Compression Ratio ◽  
Modulus Of Elasticity ◽  
Modulus Of Rupture ◽  
Horizontal Shear ◽  
Fast Growing

In order to improve the mechanical strength of LVL, metal net was inserted into the LVL (metal net-LVL composite) made of fast-growing poplar. In this study, the effects of compression ratio and lay angle of metal net (which is lay angle for short in this paper) on the mechanical properties of the metal net-LVL composite was investigated in a comparative way. In order to find out the optimum compression ratio and lay angle, the modulus of rupture (MOR), modulus of elasticity (MOE) and horizontal shear strength of the metal net-LVL composite were tested. The results showed that the effects of the compression ratio on MOR, MOE and horizontal shear strength were significant, with increasing of compression ratio, the values of MOR and MOE showed an earlier raised and later decreased state, and had the maximum values at 31%. The effects of lay angle on MOR and MOE were significant, the values of MOR and MOE increased first and then decreased with lay angle increasing, and the maximum values were obtained at 20°, though there were no significant effects on horizontal shear strength, there were the maximum values at 20°. Therefore, when the compression ratio was 31% and the lay angle was 20°, the metal net-LVL composite could obtain the optimal overall mechanical properties.

Hot-pressing stress graded aspen veneer for laminated veneer lumber (LVL)

Holzforschung ◽  
2005 ◽  
Vol 59 (1) ◽  
pp. 10-17 ◽  
Author(s):  
Brad Jianhe Wang ◽  
Chunping Dai
Keyword(s):  
Populus Tremuloides ◽  
Hot Pressing ◽  
Strength Properties ◽  
Bending Stiffness ◽  
Product Performance ◽  
Target Temperature ◽  
Lower Stress ◽  
Important Species ◽  
Laminated Veneer Lumber ◽  
Pressing Time

Abstract Aspen (Populus tremuloides) is emerging as an important species for laminated veneer lumber (LVL) products in North America. During LVL manufacturing, both veneer stress grades and hot-pressing schedules are vital to product performance. In this study, an experimental design with four three-level variables comprising veneer moisture content (MC), veneer stress grade, platen pressure, and glue spread level was employed to investigate their effects on pressing behavior and stiffness and strength properties of LVL panels. The results show that, within the ranges studied, glue spread level and platen pressure were the two most important variables affecting the hot-pressing time needed for the innermost glueline to reach a target temperature of 105°C. The MC from the glue (mainly in the glueline) affected the rise of the innermost temperature more significantly than the MC in the veneer. Among the four variables studied, veneer stress grade and veneer MC were the two dominant variables that affect LVL stiffness and strength properties. Flat-wise and edge-wise bending stiffness (MOE) and strength (MOR) of LVL panels made from higher stress grade veneers were higher compared to those made from lower stress grade veneers, but there was no direct correlation between LVL shear strength and veneer stress grade. In addition, LVL edge-wise bending stiffness had the highest veneer MC tolerance among all LVL stiffness and strength properties. Further, LVL stiffness enhancement (the ratio of LVL MOE over veneer MOE) was lower with higher stress grade veneers than with lower stress grade veneers. These findings are useful for manufacturing high-stiffness LVL for engineered applications.

Properties of Particleboard Manufactured with Modified Urea-Formaldehyde Resin

2010 ◽  
Vol 150-151 ◽  
pp. 1135-1138
Author(s):  
Ji Zhi Zhang ◽  
Jian Zhang Li ◽  
Shi Feng Zhang
Keyword(s):  
Hot Pressing ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Modulus Of Rupture ◽  
Formaldehyde Resin ◽  
Pressing Temperature ◽  
Technical Parameters ◽  
Pressing Time ◽  
Uf Resin ◽  
Modified Urea

This study modified urea-formaldehyde (UF) resin with a modifier, and focused on properties of particleboard manufactured with the modified UF resin. The orthogonal design was used to analyze the effects of different levels of hot-pressing temperature, hot-pressing time, glue content, and waterproof agent content on the modulus of rupture (MOR), internal bonding strength (IB), and formaldehyde emission (FE) of the particleboard, and thus determined the optimum technical parameters of hot-pressing. The conclusions were as follows: (1) the modifier used in this study could significantly reduce the free formaldehyde content of UF resin and the formaldehyde emission of particleboard; (2) the optimum hot-pressing technical parameters of particleboard manufactured with the modified UF resin were hot-pressing temperature 180°C, hot-pressing time 50s/mm, glue content 12%, and waterproof agent content 0.6%. The MOR and IB under the optimum technical parameters could reach 20.7 and 0.47 MPa, and the FE was 0.85 mg/L.

scholarly journals Influence of technological cracks of peeled vener on the shear strength of ultralam bars

2021 ◽  
Vol 244 ◽  
pp. 09010
Author(s):  
Stefania Mironova
Keyword(s):  
Shear Strength ◽  
Building Material ◽  
Phenol Formaldehyde ◽  
Adhesive Layer ◽  
Strength Properties ◽  
Glue Line ◽  
Adhesive Material ◽  
Laminated Veneer Lumber ◽  
Peeling Process ◽  
Veneer Surface

The aim of the research is to study the shear strength of laminated veneer lumber (LVL) when working on shear in four different planes. To determine the influence of the presence of technological cracks formed in the peeling process, an experiment was carried out for which four types of samples were used. The load was applied parallel and perpendicular to the glue line and the direction of the peeled veneer fibers. As tests have shown, the technological weakening of peeled veneer reduces the strength properties of a multilayer glued veneer bar, especially for shear along the glue lines and perpendicular to the direction of the peeled veneer fibers, where the maximum number of microcracks is located. The analysis of these microcracks is carried out and their widths are determined. The width of the studied cracks was from 152 to 94 μm. There is no adhesive layer in the microcracks of this building material, which may indicate insufficient wetting of the veneer surface with the adhesive material, or the difficulty of penetration of high-molecular phenol-formaldehyde glue into the cavity of microcracks.

Research on Mechanical Properties of Bambusa Distegia Thread Plywood

2012 ◽  
Vol 482-484 ◽  
pp. 1394-1397
Author(s):  
Yun Shui Yu ◽  
Wei Hong Zhou ◽  
Xue Liu ◽  
Xue Liang Xiong
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Shear Strength ◽  
Modulus Of Elasticity ◽  
Hot Pressing ◽  
Modulus Of Rupture ◽  
Pressing Pressure ◽  
Horizontal Shear ◽  
Concrete Form

Bambusa distegia were used to make bamboo thread plywood by the process of producing thread, dipping thread into glue, assembling pattern and pressing. Influence of hot pressing pressure on mechanical properties of bambusa distegia thread plywood was investigated, which was 2.0MPa，2.5MPa，3.0MPa，3.5MPa and 4.0MPa respectively. The results indicate that the modulus of rupture(MOR), modulus of elasticity(MOE), compressive strength(CS), and horizontal shear strength(HSS) increase with the increasing of hot pressing pressure. Mechanical properties of the Bambusa distegia thread plywood are higher than the indices of plywood for concrete form and the indices of plywood for container flooring.

scholarly journals Influence of Four Ageing Methods on the Mechanical Properties of Bamboo Scrimber

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hongyan Wang ◽  
Shaofei Yuan ◽  
Jian Zhang ◽  
Qin Li
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Modulus Of Rupture ◽  
Accelerated Ageing ◽  
Horizontal Shear ◽  
Testing Methods ◽  
Holding Power ◽  
Bamboo Scrimber ◽  
Sequence Method ◽  
Weather Resistance

In this study, the six-cycle accelerated ageing method (method I), the 6 h boiling-freezing-drying method (method II), the wet circulation method (method III), and the boiling-testing method (method IV), which are accelerated ageing testing methods, were used to study the ageing resistance of bamboo scrimber. Changes in the nail-holding power of the plane, the side, and the end face of untreated/treated bamboo scrimber were analyzed systematically, including other changes in mechanical properties, such as the horizontal shear strength, the modulus of rupture (MOR), and the modulus of elasticity (MOE) along the smooth grain, etc. The results show that all mechanical properties decreased after treatment with the four accelerated ageing testing methods: the nail-holding power decreased by 4%~42% on the plane, 8%~40% on the side, and 5%~66% on the end face. The horizontal shear strength decreased by 3.1%~16.7%, the MOR decreased by 15%~27.2%, and the MOE decreased by 2.6%~12.8%. The nail-holding power of the three sides and the MOR were the most affected properties after treatment. So, the nail-holding power and the MOR can be chosen as important indices to evaluate bamboo scrimber’s weather resistance. For the four accelerated ageing testing methods, the degree of influence on the nail-holding power was in this sequence: method I > method III > method IV > method II. However, after comprehensive consideration, the degree of influence on the mechanical properties was in this sequence: method I > method IV > method III > method II.

scholarly journals Comparative Analysis of Shear Strength Parallel to Fiber of Different Local Bamboo Species in the Philippines

2021 ◽  
Vol 13 (15) ◽  
pp. 8164
Author(s):  
Brian E. Bautista ◽  
Lessandro E. O. Garciano ◽  
Luis F. Lopez
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Comparative Analysis ◽  
Strength Properties ◽  
The Philippines ◽  
Bamboo Species ◽  
Test Protocol ◽  
Future Design ◽  
Average Shear Strength ◽  
Bambusa Vulgaris

There are limited published studies related to the mechanical properties of bamboo species in the Philippines. In this study, the shear strength properties of some economically viable bamboo species in the Philippines were properly characterized based on 220 shear test results. The rationales of selecting this mechanical property are the following: (1) Shear strength, parallel to the fiber, has the highest variability among the mechanical properties; and (2) Shear is one of the governing forces on joint connections, and such connections are the points of failure on bamboo structures when subjected to extreme loading conditions. ISO 22157-1 (2017) test protocol for shear was used for all tests. The results showed that Bambusa blumeana has the highest average shear strength, followed by Gigantochloa apus, Dendrocalamus asper, Bambusa philippinensis, and Bambusa vulgaris. However, comparative analysis, using One-way ANOVA, showed that shear strength values among these bamboo species have significant differences statistically. A linear regression model is also established to estimate the shear strength of bamboo from the physical properties. Characteristic shear strength is also determined using ISO 12122-1 (2014) for future design reference.

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