scholarly journals Variability in the mechanical properties of commercially available thermally modified hardwood lumber

BioResources ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. 6083-6099
Author(s):  
Juan J. Gonzalez ◽  
Brian Bond ◽  
Henry Quesada
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Untreated Wood ◽  
Red Maple ◽  
Yellow Poplar ◽  
Bending Modulus ◽  
Tangential Shrinkage ◽  
Improved Performance ◽  
Mechanical Performances

Research indicates that users of thermally modified wood lack information regarding the improved performance and any variations that may exist for the “same” product when manufactured by different companies. The goal of this study was to evaluate the variability in mechanical properties of three thermally modified hardwoods and determine the variability between three different manufacturers. To determine the hardness, bending (modulus of elasticity and module of rupture) and shrinkage values, testing was conducted following ASTM standard D143. The samples were conditioned at 20 °C and a relative humidity of 65% until they reached an equilibrium moisture content before testing. Analysis of variance was used to determine the variability within and between the different processes used by each company. Seven out of 18 (39%) tests indicated that there were statistical differences regarding the mechanical performances of the wood samples. Yellow poplar had the least variation between companies (only difference in equilibrium moisture content, EMC) and red maple had the most (hardness, tangential shrinkage, and EMC). While the means for these properties were statistically different, the differences in application for hardness and EMC are slight. For example, the largest difference between processes in hardness was 83.6 kg, for tangential shrinkage, 0.45% and 1.37% for EMC. These differences are suggested to be inconsequential when compared to the values that exist between different species of untreated wood.

scholarly journals Effect of Different Hydrothermal Treatments (Steam and Hot Compressed Water) on Physical Properties and Drying Behavior of Yellow-Poplar (Liriodendron tulipifera)

2019 ◽  
Vol 69 (1) ◽  
pp. 42-52
Author(s):  
Sohrab Rahimi ◽  
Kaushlendra Singh ◽  
David DeVallance
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Moisture Content ◽  
Yellow Poplar ◽  
Pressure Steam ◽  
Percent Moisture ◽  
Drying Behavior ◽  
Hot Compressed Water ◽  
And Control ◽  
Control Samples

Abstract Nonchemical high-pressure steam treatments have been intensively researched and commercialized to produce chemical-free wood products with enhanced properties. However, the utilization of high-pressure steam involves vapor-phase reactions using high-temperature steam generated at the expense of high energy input. In this research, influences of reaction media (steam and hot-compressed water) and temperature (100°C and 140°C) during thermal treatment on physical properties and drying behavior of yellow-poplar (Liriodendron tulipifera) heartwood were compared. The length, width, and thickness of the samples were 22.53 mm, 17.18 mm, and 16.72 mm, respectively. After the treatment, the samples were dried under an isothermal temperature condition of 105°C. Data on moisture content and time of drying from drying experiments were fitted with unsteady-state molecular transport equations to calculate overall liquid diffusion coefficients. Dimensions, weight, and true volume of samples were measured for green, thermally treated, and dried samples and the values were used to calculate selected physical characteristics. Additionally, selected mechanical properties were evaluated for samples conditioned to 13 percent moisture content. Results showed that intensified hot-compressed water-treated and control samples had the highest and lowest saturated moisture contents (101% and 44%), respectively, immediately after treatments. Intensified steam-treated and control samples had the highest and lowest total porosity (95% and 82%), respectively. Furthermore, mild hot-compressed water-treated samples showed the greatest compression strength (47.8 MPa) at 13 percent moisture content. Except for steam treatment at 140°C, other treatments significantly decreased the diffusion coefficient. Collectively, samples treated with hot-compressed water at 100°C showed the most improved mechanical properties.

Physical properties of earlywood and latewood of Pinus radiata D. Don: Anisotropic shrinkage, equilibrium moisture content and fibre saturation point

Holzforschung ◽  
2005 ◽  
Vol 59 (6) ◽  
pp. 654-661 ◽  
Author(s):  
Shusheng Pang ◽  
Alfred Herritsch
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Pinus Radiata ◽  
Growth Ring ◽  
Fibre Saturation Point ◽  
Longitudinal Shrinkage ◽  
Saturation Point ◽  
Breast Height ◽  
Second Growth ◽  
Tangential Shrinkage

Abstract Anisotropic shrinkage (tangential and longitudinal), equilibrium moisture content (EMC) and fibre saturation point (FSP) were measured for separated earlywood (EW) and latewood (LW) of a 0.75-m-long log of 20-year old Pinus radiata that was cut at breast height from a selected tree in the forest of Central North Island, New Zealand. The experimental results have shown that at 12% moisture content (MC), tangential shrinkage was 3.23% for EW and 3.90% for LW, with an overall average of 3.56%. Longitudinal shrinkage was 0.23% for EW and 0.21% for LW with an overall average of 0.22%. Shrinkage for the oven dry (OD) state showed similar trends to those at 12% MC in terms of the differences between EW and LW. The tangential and longitudinal shrinkage varied significantly along the radius from pith to bark. The EW tangential shrinkage increased from pith to the seventh growth ring and then remained relatively constant until the last ring adjacent to the bark. The LW tangential shrinkage also increased from the pith outwards until the seventh growth ring, but beyond that was more variable than the EW shrinkage. Both EW and LW showed similar longitudinal shrinkage, with the highest values in the second growth ring, from which the shrinkage decreased exponentially towards the bark. LW had a slightly higher EMC than EW at a relative humidity (RH) below 80%, but the trend was reversed for RH above 80%. The EMC differences between EW and LW were less than 0.6%. The overall average FSP for Pinus radiata was 29.1%, with actual values varying from 25% to 32.8%. The earlywood FSP (28.9%) was slightly lower than that of the latewood (29.4%).

scholarly journals Influence of a thermal treatment on the tensile strength and equilibrium moisture content of bamboo (Guadua angustifolia Kunth)

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3103-3111
Author(s):  
Ricardo Acosta ◽  
Jorge A. Montoya ◽  
Goran Schmidt
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Thermal Treatment ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Physical And Mechanical Properties ◽  
Thermal Treatments ◽  
Lignocellulosic Materials ◽  
Basal Section ◽  
Notable Increase

Thermal treatments applied to lignocellulosic materials were found to induce internal chemical reactions, which modified the physical and mechanical properties and dimensional stability of the material. A 3-year-old basal section of bamboo (Guadua angustifolia Kunth), with no nodes and no skin, was subjected to a thermal treatment at temperatures which ranged from 160 to 200 °C for 1 to 4 h. The tensile stiffness showed a slight increase with temperature and time, while the tensile strength showed a notable increase at 160 °C for 2 h. There was a 5% difference in the equilibrium moisture content at 80% relative humidity between the untreated samples and the 200 °C, 4 h treatment.

scholarly journals EFEITO DA VAPORIZAÇÃO NA UMIDADE DE EQUILÍBRIO E SUA IMPLICAÇÃO NAS PROPRIEDADES MECÂNICAS DA MADEIRA DE Eucalyptus dunnii MAID

FLORESTA ◽  
2001 ◽  
Vol 31 (12) ◽  
Author(s):  
Elias Taylor Durgante Severo ◽  
Ivan Tomaselli ◽  
Ghislaine Miranda Bondueli ◽  
Marcos Antônio De Rezende
Keyword(s):  
Mechanical Properties ◽  
Relative Humidity ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Eucalyptus Dunnii ◽  
Remarkable Reduction ◽  
Different Levels ◽  
Do So

O objetivo deste estudo foi avaliar o efeito da vaporização sobre a umidade de equilíbrio e sua implicação nas propriedades mecânicas da madeira de Eucalyptus dunnii. Para isso de um lote de toras desta espécie separou-se cerca de 1/3 para controle, enquanto o restante foi submetido à vaporização nas condições de temperatura e umidade relativa de 100ºC e 100%, respectivamente. Após retirar-se uma prancha central destas toras, as mesmas foram transformadas em vigotas de 8 cm x 8 cm. Entre as vigotas provenientes das toras vaporizadas cerca da metade foi novamente vaporizada nas mesmas condições previamente descritas por um período de 3 horas após uma hora de aquecimento inicial. Desta forma obteve-se três níveis de comparação (controle, vaporizado em toras e madeira pré-vaporizada). Posteriormente estas vigotas foram transformadas em corpos-de-prova segundo a norma COPANT e condicionados em câmara climatizada a 21ºC e 65% de temperatura e umidade relativa, respectivamente. Os resultados mostraram uma redução significativa no teor de umidade de equilíbrio entre os níveis de vaporização empregados e madeira controle, evidenciando a necessidade da correção das propriedades mecânicas da madeira desta espécie para um mesmo teor de umidade antes de sua utilização. Vaporization effect on the equilibrium moisture content and its implication on the mechanical properties in Eucalyptus dunnii wood Abstract The aim of this study was to evaluate the vaporization effects on the equilibrium moisture content and its implication on the mechanical properties of Eucalyptus dunnii. To do so, about two thirds of the logs were vaporized at 100oC and 100% (temperature and relative humidity respectively) for 20 hours, while the remaining logs were kept as control. From each log, a central plank with 8 cm of thickness is taken, from which small beams of 8 cm x 8 cm was taken. Half of the small beams from the vaporized logs were once again submitted to vaporization under the same previously described conditions for a period of 3 hours, thus obtaining three different levels of comparison (control, vaporized on logs and presteaming wood). Subsequently the beams were transformed in samples by the COPANT norm and conditioned in climatized kiln (21ºC/65% relative humidity) until the higorscopic equilibrium. The results showed a remarkable reduction on the equilibrium moisture content with the vaporization conditions used, showing the necessity of the mechanical properties correction to the same moisture content.

scholarly journals Characterisation of Physical and Mechanical Properties of Unthinned and Unpruned Plantation-Grown Eucalyptus nitens H.Deane & Maiden Lumber

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 194 ◽  
Author(s):  
Mohammad Derikvand ◽  
Nathan Kotlarewski ◽  
Michael Lee ◽  
Hui Jiao ◽  
Gregory Nolan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Shear Strength ◽  
Moisture Content ◽  
Physical And Mechanical Properties ◽  
Modulus Of Rupture ◽  
Eucalyptus Nitens ◽  
Linear Regression Models ◽  
Bending Modulus ◽  
Small Wood

The use of fast-growing plantation eucalypt (i.e., pulpwood eucalypt) in the construction of high-value structural products has received special attention from the timber industry in Australia and worldwide. There is still, however, a significant lack of knowledge regarding the physical and mechanical properties of the lumber from such plantation resources as they are mainly being managed to produce woodchips. In this study, the physical and mechanical properties of lumber from a 16-year-old pulpwood Eucalyptus nitens H.Deane & Maiden resource from the northeast of Tasmania, Australia was evaluated. The tests were conducted on 318 small wood samples obtained from different logs harvested from the study site. The tested mechanical properties included bending modulus of elasticity (10,377.7 MPa) and modulus of rupture (53 MPa), shear strength parallel (5.5 MPa) and perpendicular to the grain (8.5 MPa), compressive strength parallel (42.8 MPa) and perpendicular to the grain (4.1 MPa), tensile strength perpendicular to the grain (3.4 MPa), impact bending (23.6 J/cm2), cleavage (1.6 kN) and Janka hardness (23.2 MPa). Simple linear regression models were developed using density and moisture content to predict the mechanical properties. The variations in the moisture content after conventional kiln drying within randomly selected samples in each test treatment were not high enough to significantly influence the mechanical properties. A relatively high variation in the density values was observed that showed significant correlations with the changes in the mechanical properties. The presence of knots increased the shear strength both parallel and perpendicular to the grain and significantly decreased the tensile strength of the lumber. The results of this study created a profile of material properties for the pulpwood E. nitens lumber that can be used for numerical modelling of any potential structural product from such a plantation resource.

scholarly journals Physical and Mechanical Properties of Fast Growing Polyploid Acacia Hybrids (A. auriculiformis × A. mangium) from Vietnam

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 717
Author(s):  
Dang Duc Viet ◽  
Te Ma ◽  
Tetsuya Inagaki ◽  
Nguyen Tu Kim ◽  
Nghiem Quynh Chi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Young’S Modulus ◽  
Equilibrium Moisture Content ◽  
Compression Strength ◽  
Young's Modulus ◽  
Basic Density ◽  
Physical And Mechanical Properties ◽  
Modulus Of Rupture ◽  
Acacia Auriculiformis

Acacia plants are globally important resources in the wood industry, but particularly in Southeast Asian countries. In the present study, we compared the physical and mechanical properties of polyploid Acacia (3x and 4x) clones with those of diploid (2x) clones grown in Vietnam. We randomly selected 29 trees aged 3.8 years from different taxa for investigation. BV10 and BV16 clones represented the diploid controls; X101 and X102 were the triploid clones; and AA-4x, AM-4x, and AH-4x represented neo-tetraploid families of Acacia auriculiformis, Acacia mangium, and their hybrid clones. The following metrics were measured in each plant: stem height levels, basic density, air-dry equilibrium moisture content, modulus of rupture (MOR), modulus of elasticity (MOE), compression strength, and Young’s modulus. We found that the equilibrium moisture content significantly differed among clones, and basic density varied from pith-to-bark and in an axial direction. In addition, the basic density of AA-4x was significantly higher than that of the control clones. Furthermore, the MOR of AM-4x was considerably lower than the control clones, whereas the MOE of X101 was significantly higher than the control values. The compression strength of AM-4x was significantly lower than that of the control clones, but AH-4x had a significantly higher Young’s modulus. Our results suggest that polyploid Acacia hybrids have the potential to be alternative species for providing wood with improved properties to the forestry sector of Vietnam. Furthermore, the significant differences among the clones indicate that opportunities exist for selection and the improvement of wood quality via selective breeding for specific properties.

Fiberboard bending properties as a function of density, thickness, resin, and moisture content

Holzforschung ◽  
2008 ◽  
Vol 62 (5) ◽  
Author(s):  
John F. Hunt ◽  
Jane O'Dell ◽  
Chris Turk
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Pinus Contorta ◽  
Phenolic Resin ◽  
Three Dimensional ◽  
Modulus Of Rupture ◽  
True Density ◽  
Bending Properties ◽  
Bending Modulus ◽  
Density Values

Abstract Fibers from treetop residues of lodgepole pine (Pinus contorta) and recycled old corrugated containers were used to fabricate wet-formed fiberboard panels over a range of densities from 300 to 1100 kg m-3, a thickness range from 1.3 to 4.8 mm, and phenolic resin contents from 0% to 4.5%. The panels were then tested after conditioning in 50% and 90% relative humidity (RH) environments. Density, thickness, equilibrium moisture content, bending modulus of elasticity (MOE), and modulus of rupture (MOR) were measured for each panel. Panel apparent-density increased with thickness, but this may be due to surface effects rather than true density values. The equilibrium moisture content approximately doubled for the panels in the 90% RH environment, compared to 50% RH. At 50% and 90% RH conditions, equilibrium moisture contents decreased significantly when only 0.5% resin was added and remained essentially the same with increasing resin levels. In this study, both MOE and MOR increased with approximately the square of density. MOE increased, whereas MOR showed no clear effects as thickness and resin amount increased. This research is part of a larger program for developing an understanding of panel properties for engineered three-dimensional fiberboard products.

scholarly journals Modifications of Physical and Mechanical Characteristics Induced by Heat Treatment: Case Study on Ayous Wood (Triplochiton scleroxylon K. Schum)

2020 ◽  
Vol 3 (1) ◽  
pp. 27
Author(s):  
Emiliano Gennari ◽  
Rodolfo Picchio ◽  
Damiano Tocci ◽  
Angela Lo Monaco
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Mechanical Characteristics ◽  
Bending Strength ◽  
Basic Density ◽  
Untreated Wood ◽  
Thermal Modification ◽  
Biological Origin ◽  
Physical And Mechanical Characteristics

Wood is a material of biological origin of fundamental importance for artisan and industrial uses. In outdoor environments, it is very attractive, but easily subjected to degradation. A valid alternative to chemical preservatives is thermal modification. The aim of this study is to evaluate ayous wood industrially subjected to thermal modification (215 °C) in order to emphasize the influence of heat treatment on selected physical and mechanical characteristics. As a result of the heat treatment, the physical and mechanical properties are generally reduced: the density in natural wood (TQ) was 379 kg/m3, in heat treated wood (TT) 319 kg/m3; the basic density in TQ was 327 kg/m3, in TT 299 kg/m3; the axial compression strength of TT was reduced by 18.1%; and the static bending strength of TT was reduced by 41.4% compared to untreated wood at 10% equilibrium moisture content (EMC). In addition, the samples, under the same environmental conditions in the laboratory, reached the equilibrium moisture content of 10% in TQ and 4% in TT.

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