Properties Of Pine Wood Research Articles

Influence of thermal treatment on mechanical properties of pine wood with regard to prime cost

Influence of thermal treatment on mechanical properties of pine wood with regard to prime cost

Effect of Thermal Modification on the Density, Durability, Dimensional Stability, and Mechanical Properties of Pinus caribaea

Pinus caribaea (Pine) is an underutilized timber species in Sri Lanka due to its low density, durability, dimensional stability, and undesirable colour. This research aims to examine the enhancements in the physical and mechanical properties of Pinewood through thermal modification (TM) and compare the properties of the TM wood with kiln-dried and untreated wood and with the properties of high-graded timbers of Tectona grandis (teak) and Koompassia malaccensi (kempas). TM is a process that involves heating wood to high temperatures (2000 C) in the absence of oxygen, which removes the moisture and creates changes in the wood at the cellular level. The effectiveness of the thermal modification on density, modulus of rupture (MOR), modulus of elasticity (MOE), moisture content, dimensional stability, durability, and colour was studied. Specific gravity of thermally modified wood was 6% higher than untreated wood, but lower than teak and kempas. MOR and MOE values were 35.75% and 46.46% respectively higher than untreated wood. Equilibrium moisture content was reduced after TM and volumetric shrinkage of TM was reduced to 2.16% and swelling under liquid water contact was reduced to 2.37%. Thermally modified timber was classified as not durable (DC 5) based on field test (EN 252, 2014) results. However, TM timber was slightly durable (DC 4) according to laboratory tests and showed better fungal resistance. The wood underwent a darkening effect as a result of thermal modification, resembling the colour of teak. The cost of TM was 13.1% higher than kiln drying. Improved dimensional stability, enhanced bending strength, and attractive appearance demonstrate the potential of thermal modification as a promising alternative for transforming P. caribaea wood into high-value raw material. TM timber finds suitable applications in indoor furniture and joinery projects. However, due to its lack of termite resistance, preservative treatment is recommended for outdoor ground contact usage.
 
 Keywords: Thermally modified timber, Mechanical properties, Dimensional stability, Durability,
 Pinus caribaea

The impact of density, temperature, moisture, and test direction on the thermal conductivity coefficient in pine wood

The article focuses on the study of the thermal properties of pine wood, a material traditionally used in construction, especially in Poland. The trend towards sustainable construction necessitates a deeper analysis of its properties. Due to the insufficient amount of data in the literature on the thermal conductivity of pine wood, detailed studies were conducted taking into account different wood densities. Seasoned wood samples were subjected to various processes and tests, measuring the heat conduction coefficient under different conditions. These results are relevant in the context of sustainable construction and will assist in further research on wood as a building material. The studies also took into account the effects of temperature and humidity on the thermal properties of wood, which is crucial for its application in various environmental conditions.

Variation of Physical and Mechanical Properties of Pinus Sylvestris L. Wood in the Boreal Zone of the European Northeast

The study considers variational aspects of physical and mechanical properties of Scots pine (Pinus sylvestris L.) wood depending on conditions and growth areas in the boreal zone of the European Northeast. Anatomical traits of xylem and its strength properties were analyzed. Based on the data received, statistical processing of the material was carried out using correlation and multivariate analysis. The impact of hazardous air emissions on variation of linear dimensions in structural elements of the annual height increment in the trunk diameter was estimated. A varying nature of the influence of environmental factors on the formation of strength properties of P. sylvestris wood in growth areas was attested. The variation value of basic wood density decreases as soil and hydrological conditions of growth improve. A significant negative correlation between basic wood density and distance to sources of hazardous air emissions in the areas of concentration of industrial enterprises was established. The results of multivariate analysis make it possible to reveal the weight of the influence of environmental factors and biometric characteristics of wood on volumetric and strength properties of pine wood. Growth in the impact zone of air emissions from large industrial enterprises in the study area does not produce a significant effect on the dynamics of wood strength properties, taking into account various growth conditions. For Scots pine growing in the European Northeast, the study determined a significant impact of the size and structure of the annual height increment of the trunk in terms of diameter, as well as the position of the wood sample in terms of trunk volume, on strength properties of pine wood.

Pine wood extraction by fermentation to improve its acoustical efficiency

Wood is a main material in the construction of musical instruments and speaker boxes, especially in developed countries. This study investigated the changes in acoustic properties of pine wood during the processes of fermentation, water washing, and organic washing solvent. The results indicated that both methods of water washing and ethanol-acetone mixture washing of the samples improved the values of density, modulus of elasticity, elastic stiffness, acoustic coefficient, vibration damping, and acoustic conversion efficiency. The effect of ethanol-acetone mixture washing was greater than water washing the samples. Additionally, results revealed that pretreatment before ethanol-acetone mixture washing had the most effect on vibration damping and acoustic conversion efficiency values. In general, the values obtained from ethanol-acetone mixture washing resulted in more improvement in acoustic properties compared to water washing, but the results showed that the pretreatment before water washing had a greater effect on the values of density, modulus of elasticity, elastic stiffness, and acoustic coefficient.

The Influence of Physical Mixing and Impregnation on the Physicochemical Properties of Pine Wood Activated Carbon Produced by One-Step ZnCl2 Activation.

In this study, two different sample preparation methods to synthesize activated carbon from pine wood were compared. The pine wood activated carbon was prepared by mixing ZnCl2 by physical mixing, i.e., "dry mixing" and impregnation, i.e., "wet mixing" before high temperature carbonization. The influence of these methods on the physicochemical properties of activated carbons was examined. The activated carbon was analyzed using nitrogen sorption (surface area, pore volume and pore size distribution), XPS, density, Raman spectroscopy, and electrochemistry. Physical mixing led to a slightly higher density carbon (1.83 g/cm3) than wet impregnation (1.78 g/cm3). Raman spectroscopy analysis also showed that impregnation led to activated carbon with a much higher degree of defects than physical mixing, i.e., ID/IG = 0.86 and 0.89, respectively. The wet impregnated samples also had better overall textural properties. For example, for samples activated with 1:1 ratio, the total pore volume was 0.664 vs. 0.637 cm3/g and the surface area was 1191 vs. 1263 m2/g for dry and wet mixed samples, respectively. In the electrochemical application, specifically in supercapacitors, impregnated samples showed a much better capacitance at low current densities, i.e., 247 vs. 146 F/g at the current density of 0.1 A/g. However, the physically mixed samples were more stable after 5000 cycles: 97.8% versus 94.4% capacitance retention for the wet impregnated samples.

The study of selected properties of pine wood (Pinus sylvestris L.) subjected to acetylation

The study of selected properties of pine wood (Pinus sylvestris L.) subjected to acetylation. In the paper pine wood was subjected to acetylation with acetic anhydride and mixture of acetic anhydride and glacial acetic acid (50:50)v/v. After modification process density, WPG index, water absorbability, volume swelling and colour of wood were carried out and compared with results obtained for unmodified pine wood. Based on the obtained results the density of acetylated pine wood was increased for each group of samples. The highest WPG index was obtained for previously dried wood modified with acetic anhydride (15.6%) or mixture of acetic anhydride and glacial acetic acid (10.5%). Acetylation process with acetic anhydride or mixture of acetic anhydride and glacial acetic acid of samples, which were extracted (in chloroform-ethanol 93:7w/w mixture) and dried before modification, had beneficial effect on water absorbability of pine wood. These samples after 1001h (about 42 days) of soaking in water reached the lowest values of water absorbability (about 94%). Moreover, the volume swelling were significantly reduced for samples after double impregnation cycle (both in case of modification with acetic anhydride or mixture of acetic anhydride and glacial acetic acid). Wood after acetylation process was slightly darker than unmodified pine wood. Acetylation of samples, which were dried and soaked in DMF before modification, caused significant darkening of pine wood. The obtained colour was similar to colour of furfurylated wood (Kebony wood) or some of exotic species.

Timber Properties and Cellulose Crystallites Size in Pine Wood Cut in Different Sawing Patterns after Pretreatment with CH3COOH and H2O2 and Densification

One process to improve wood quality is densification or wood surface compression. Our study analyzed the changes in some basic properties of pine wood, including its anatomical structure, density, modulus of elasticity (MOE), and dimensions of cellulose crystallites, after densification following soaking pretreatment in CH3COOH and H2O2 at a concentration of 20%. Samples were sawn in radial and tangential directions for analysis of the wood. The results showed a change in the shape of tracheid cells from hexagonal to oval, as well as damage to the ray cell constituents on the tangential surface. The thickness decrease of the samples was in accordance with the target, which meant that spring-back was short. In general, the tangential boards had a higher density than the radial boards, with a lower MOE and crystallite dimensions. Our findings showed that the densified tangential board was stronger than the radial board.

The Influence of Habitat Conditions on the Properties of Pinewood

This article starts a series of articles on dependences between the conditions of the growth of trees in forests and the technical aspects and directions of using the raw material obtained from these trees. This is a key feature for wood purchasers because it determines the efficiency of production and directly affects the final financial result of their activity. Wood represents an environmentally sustainable and renewable material, which is a widely available raw material on the market and must meet specific quality and strength requirements. These parameters indicate the utility values of wood and the possibilities of its use. One of the factors influencing the properties of wood is the type of the forest habitat it comes from. In order to determine this influence, tests were carried out to show how tree growth conditions affected changes in the density and strength of raw wood. The assumption (hypothesis) about the correlation between the static bending strength of Scots pine (Pinus sylvestris L.) wood and the forest habitat was verified on four forest types, i.e., fresh coniferous forest (FCF), fresh mixed coniferous forest (FMCF), fresh mixed forest (FMF) and fresh forest (FF). The properties depend largely on the wood structure, its origin on the cross section and the length of the stems. The raw material selected for the study came from Scots pine trees growing in forests in central Poland. The study confirmed the influence of the habitat on changes in the density and strength of pinewood. There was a correlation between the habitat FMCF and the quality parameters of the raw material, which reflected the wood structure r = 0.775; p < 0.05.

Selected physical and mechanical properties of Scots pine (Pinus sylvestris L.) wood from stands of younger age classes as criteria for rational utilization of timber

The aim of this study was to assess the quality of Scots pine (Pinus sylvestris L.) wood depending on the age of trees, forest site conditions and social class of tree position in the stand. Analyses were based on the determination of specific density and static bending strength, as well as the strength quality coefficient. It was to determine changes in physical and mechanical properties of timber depending on tree age as well as growth conditions reflected in the forest site such as fresh mixed coniferous forests and fresh mixed broadleaved forests. Experimental plots were established in 6 localities with 30, 40 and 60-year-old trees. In each of the stands, a 1-hectare experimental plot was established. Based on the measured DBH and tree height, dimensions of three mean sample trees were calculated, while the classification of social class of tree position in the stand developed by Kraft (1884) was also applied. Analyses were conducted on wood samples with 12% moisture content. Strength tests on wood samples were performed on an Instron 33RH204 universal strength testing machine. A detailed analysis showed properties of pine wood are improved with an increase of tree age in both forest sites. Statistically significant differences were observed for wood density and static bending strength. More advantageous properties were observed for wood of pines from the less fertile forest site, i.e., fresh mixed coniferous forests. Density and static bending strength were markedly determined by tree age and growth conditions. The static bending strength quality coefficient from pines growing in the fresh mixed coniferous forests increased between 30 and 40 years, similarly as it was for the fresh mixed broadleaved forests, while between 40 and 60 years, it deteriorated for the fresh mixed coniferous forests. Wood density from the fresh mixed coniferous forests was by 3% to 7% greater than pines growing in fresh mixed broadleaved forests. In turn, static bending strength of wood from pines growing in fresh mixed coniferous forests was by 4% to 10% greater than trees from the fresh mixed broadleaved forests. Keywords: Scots pine, wood properties, forest site, Poland

Juvenile and Mature Pinewoods Treated by in situ Polymerization with Poly(vinyl acetate)

This study aims to produce and characterize wood-based composites (WPC) by in situ polymerization with poly(vinyl acetate) into juvenile and mature woods from a pine specie. Vacuum-pressure method was used to impregnate the wood with a vinyl acetate monomer and benzoyl peroxide (1.5 wt%) was used as initiator. The studied WPC were characterized for treatment parameters (weight percentage gain and specific gravity), as well as chemical (by infrared spectroscopy), thermal (by thermogravimetric analysis) and mechanical (by flexure and hardness tests) features. The in situ polymerization yielded improved mechanical properties and increased thermal stabilities, which were attributed to the impregnated poly(vinyl acetate) (especially on the wood surface) as suggested by treatment parameters and infrared spectra. The presented wood treatment may be a key strategy to improve pinewood properties, especially from juvenile wood, which may overcome the properties of the pristine mature wood.

Symmetric Nature of Stress Distribution in the Elastic-Plastic Range of Pinus L. Pine Wood Samples Determined Experimentally and Using the Finite Element Method (FEM)

This article presents the results of experimental research on the mechanical properties of pine wood (Pinus L. Sp. Pl. 1000. 1753). In the course of the research process, stress-strain curves were determined for cases of tensile, compression and shear of standardized shapes samples. The collected data set was used to determine several material constants such as: modulus of elasticity, shear modulus or yield point. The aim of the research was to determine the material properties necessary to develop the model used in the finite element analysis (FEM), which demonstrates the symmetrical nature of the stress distribution in the sample. This model will be used to analyze the process of grinding wood base materials in terms of the peak cutting force estimation and the tool geometry influence determination. The main purpose of the developed model will be to determine the maximum stress value necessary to estimate the destructive force for the tested wood sample. The tests were carried out for timber of around 8.74% and 19.9% moisture content (MC). Significant differences were found between the mechanical properties of wood depending on moisture content and the direction of the applied force depending on the arrangement of wood fibers. Unlike other studies in the literature, this one relates to all three stress states (tensile, compression and shear) in all significant directions (anatomical). To verify the usability of the determined mechanical parameters of wood, all three strength tests (tensile, compression and shear) were mapped in the FEM analysis. The accuracy of the model in determining the maximum destructive force of the material is equal to the average 8% (for tensile testing 14%, compression 2.5%, shear 6.5%), while the average coverage of the FEM characteristic with the results of the strength test in the field of elastic-plastic deformations with the adopted ±15% error overlap on average by about 77%. The analyses were performed in the ABAQUS/Standard 2020 program in the field of elastic-plastic deformations. Research with the use of numerical models after extension with a damage model will enable the design of energy-saving and durable grinding machines.

The Wood of Scots Pine (Pinus sylvestris L.) from Post-Agricultural Lands Has Suitable Properties for the Timber Industry

Scots pine (Pinus sylvestris L.) is a widespread species throughout Europe and at the same time is dominant in Polish forests and of key importance in the wood industry. Pine stands are subjected to numerous environmental stresses, and one of them is the different physico-chemical and biological properties of post-agricultural soils compared to forest soils, which may affect the properties of the resulting wood and its industrial suitability. The research material taken at the height of 1.3 m from tree trunks (breast height diameter, dbh) in the form of sections and discs was collected in an 80-year-old pine stand from four plots, representing former agricultural and ancient forest land, and two types of habitats: fresh coniferous forest and fresh mixed coniferous forest. The forest habitat trophy had a decisive impact on the dendrometric characteristics and properties of pine wood (density, modulus of elasticity, bending strength, and compressive strength along the tracheids). The history of soil use (post-agricultural or forestry) did not affect the analyzed pine wood properties. Regardless of the forest habitat type and soil type history, pine wood at the dbh height showed a variability of features typical of century-old cultivated stands. Individual pine trunks were characterized by significant individual variability.

Degradation of Mechanical Properties of Pine Wood Under Symmetric Axial Cyclic Loading Parallel to Grain.

The mechanical properties of wood, respectively the elastic, plastic, and strength properties, depend on a large number of factors, due both to its structural and physical characteristics, as well as to the size, direction, nature, and speed of application of forces. Wood, generally considered to be a viscous-elastic material, has creep deformations over time under the effect of a constant load. In this study the behavior of pine wood samples was investigated due to its large utilization in different finished products, such as roof construction, furniture, outdoor applications, garden furniture, and toys. The paper aims to analyze the viscoelastic behavior of pine wood subjected to cyclically loading to traction-compression with different loads (1 kN; 1.5 kN; 2 kN), applied at different speeds (1 mm/min; 10 mm/min). It was observed that, at low speeds (1 mm/min) and low intensities of the applied force, it was possible to distinguish the three creep regions specific to wood: the primary area (primary flow), the secondary area, and finally the tertiary creep. As the force increases, the law of variation of the wood flow changes. The degradation of longitudinal elasticity modulus occurs with the increase of the number of cycles, so after 20 alternating symmetrical cycles of traction-compression of the pine wood samples, there is a decrease of its values by 35%.

ИЗМЕНЧИВОСТЬ ХАРАКТЕРИСТИК ДРЕВЕСИНЫ Pinus sylvestris L. В ДРЕВОСТОЯХ ПРИ ТЕХНОГЕННОМ ВОЗДЕЙСТВИИ

The issues of variability of pinewood (Pinus sylvestris L.) properties in growing stock located in the vicinity of operating industrial facilities is still relevant. The paper aims to assess the technogenic impact on the radial increment as well as the physical and mechanical properties of pinewood in the conditions of Northern Taiga. The impact of the distance from the source of emissions on variability of the radial increment and the volume and technical properties of wood were determined. Distribution maps of the conventional wood density and its compressive strength along the fibers inside the trunk were formed. It is found that with a decrease in the distance from the source of emissions, the average value of the radial increment of trees occurs. It is revealed that there is a decrease in wood density from the butt to the top, and from the pith to the sapwood. Also, it is determined that wood density increases as the distance to the source of emissions decreases. However, there were obtained no valid differences of the indicator of wood resistance to compression along the fibers at various distances from to the source of emissions. For citation: Schekalev R.V., Martynyuk А.А., Melekhov V.I. Variability Properties of Pinus sylvestris L. Wood in Growing Stock under Technogenic Impact. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 4, pp. 113–122. DOI: 10.37482/0536-1036-2020-4-113-122

Thermochemical and Mechanical Properties of Pine Wood Treated by In Situ Polymerization of Methyl Methacrylate (MMA)

The impregnation of low-molecular-weight monomers prior to polymerize them inside the wood may be an efficient way to improve some important wood properties. This work aimed to determine some technological properties of wood-based composites (WPC) produced by in situ polymerization, using a pine wood (Pinus elliottii Engelm.) impregnated with methyl methacrylate (MMA). For that, samples taken from both juvenile (JV) and mature (MT) pine woods were treated with MMA. Physical, mechanical, chemical, thermal and morphological features were evaluated. MMA-treated woods from both juvenile and mature woods presented superior physical, mechanical (expect brittleness) and thermal properties when compared to pristine ones. The infrared spectra and morphological analysis by scanning electron microscopy (SEM) confirmed the presence of the monomer inside the pine wood. The juvenile wood presented higher treatability than the mature wood, due to its higher content of intra- and inter-cellular spaces.

Mechanical performance of Scots pine wood from northwestern Poland – A case study

Scots pine is one of the most commercially important wood species in Europe. This study assessed the potential usefulness of pinewood from the Noteć Forest for construction purposes by evaluating its mechanical properties and investigating the influence of the site conditions on the pinewood performance. Additionally, the variability of the mechanical properties from the bark to the pith was analyzed. The results showed that the properties of pinewood varied significantly within the Noteć Forest despite similar growing conditions, which may be a result of genetic variation. Wood from Sowia Góra had the greatest density (566 kg/m3) and excellent mechanical performance (compressive strength of 64 MPa), while wood from Zamyślin exhibited the lowest density (526 kg/m3) and a lower compressive strength (54 MPa). Comparison of the properties of the pinewoods from various locations indicated that the general conditions in the forest stand, however crucial for tree growth, were not the only determinants of wood performance. The results also showed high variability in density and mechanical properties between juvenile and mature wood in all the examined trees. Overall, pinewood from the poor habitats of the Noteć Forest could be a useful raw material for various industrial purposes.

Heat Treatment of Pine Wood: Possible Effect of Impregnation with Silver Nanosuspension

The scope of the present work was to study the effects of heat treatment (at different mild temperatures) on the physicomechanical properties of pine wood, and to find out if impregnation with nanosilver may have any potential influence on the impact of heat treatment. Impregnation of wood with a 400-ppm silver nanosuspension was carried out under an initial vacuum pressure of 0.07 MPa, followed by a pressure of 0.25 MPa for thirty minutes, before heat treatment. Heat treatment was carried out under hot air at three relatively mild temperatures, 145, 165, and 185 °C. Results showed improvement of some properties in heat-treated wood at 145 °C. This was indicative of the improving impact caused by hornification and irreversible hydrogen bonding in the course of water movements due to heat treatment; significant fluctuations in the intensities of FTIR spectra bands at 1750–1500 cm−1 were corroborating evidence of chemical alterations in hemicellulose polymer. The high mass loss at temperature 185 °C, and the extreme thermal degradation thereof, overcame the improving effects of hornification and formation of irreversible hydrogen bonds, consequently mechanical properties decreased significantly. Interaction of different elements involved made it hard to predict properties in specimens modified at 165 °C. Impregnation of specimens with nanosilver suspension resulted in significant increase of mass loss in specimens heat-treated at 185 °C, and significant fluctuations in properties of specimens heat-treated at 145 °C.

A natural flavonoid, chrysin, improving wood properties via impregnation

A broader utilization of wood can be achieved by eliminating its drawbacks such as low dimensional stability with changing moisture content and low durability against various bio-organisms. Heartwood formation is nature’s solution that functions through biosynthesis and accumulation of some phenolic compounds in the cell walls, leading to more durable and stable wood. In this study, a natural flavonoid molecule, chrysin, was used to improve Scots pine wood properties. Hydrophobic chrysin was impregnated into wood after a pre-treatment. The chrysin modification reduced the water uptake of the wood cell walls by up to 33% and increased the dimensional stability of the Scots pine by up to 30%. Infrared spectroscopic analysis revealed the chemical characterization of the bio-inspired modification. In contrast to the many modification methods that establish covalent bonds between hydroxyl groups of wood polymers, chrysin was bulked into wood cell walls and stabilized by intermolecular interactions.

Combined effect of acetylation and heat treatment on the physical, mechanical and biological behavior of jack pine (Pinus banksiana) wood

A comparative study on the combined effect of heat treatment and acetylation on jack pine wood properties was undertaken and the results were compared with those of each treatment carried out individually. The dimensional stability and mechanical property of wood with different treatments were examined and statistically analyzed. The results demonstrated that combined acetylation of jack pine wood with acetic anhydride and heat treatment at 190 °C has a positive effect on the dimensional stability. Results also suggested that the dimensional stability was affected more than the modulus of rupture (MOR) and modulus of elasticity (MOE) by both heat and acetylation treatments under the experimental conditions used. In addition, the hardness increases after high temperature modification but decreases slightly after acetylation. A comprehensive investigation of the effects of heat treatment and acetylation separately and together (combination treatment) on the fungal durability of jack pine wood against a brown rot fungus, Poria placenta (pp), and a white rot fungus, Trametes versicolor (tv) has also been performed. The results indicated that the weight loss caused by fungi is reduced by both modifications. It was also found that combination of heat treatment and acetylation offers additional bioprotection. FTIR results indicated that the heat and acetylation treatments have a significant influence on the chemical properties, but less influence on their structures.