The effects of liquid nitrogen treatment on the some physical and mechanical properties of scots pine and oriental spruce wood

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

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Differences in petrophysical and mechanical properties between low- and middle-rank coal subjected to liquid nitrogen cooling in coalbed methane mining

Journal of Energy Resources Technology ◽

10.1115/1.4052614 ◽

2021 ◽

pp. 1-10

Author(s):

Menglin Du ◽

Feng Gao ◽

Chengzheng Cai ◽

Shanjie Su ◽

Zekai Wang

Keyword(s):

Mechanical Properties ◽

Pore Structure ◽

Liquid Nitrogen ◽

Coalbed Methane ◽

Bituminous Coal ◽

Thermal Damage ◽

Physical And Mechanical Properties ◽

Damage Degree ◽

Lignite Coal ◽

The Difference

Abstract Exploring the damage differences between different coal rank coal reservoirs subjected to liquid nitrogen (LN2) cooling is of great significance to the rational development and efficient utilization of coalbed methane. For this purpose, the mechanical properties, acoustic emission (AE) characteristics and energy evolution law of lignite and bituminous coal subjected to LN2 cooling were investigated based on the Brazilian splitting tests. Then, pore structure changes were analyzed to reveal the difference in the microscopic damage between lignite and bituminous coal after LN2 cooling. The results showed that compared with bituminous coal, the pore structure of lignite coal changed more obviously, which was manifested as follows: significant increases in porosity, pore diameters, and pore area; a larger transformation from micropores and transition pores to mesopores and macropores. After LN2 cooling, the thermal damage inside lignite and bituminous coal was 0.412 and 0.069, respectively. The thermal damage reduced the cohesive force between mineral particles, leading to the deterioration of the macroscopic physical and mechanical properties. Simultaneously, denser AE ringing counts and larger accumulated ringing counts were observed after LN2 cooling. Moreover, the random distribution of thermal damage enhanced the randomness of the macrocrack propagation direction, resulting in an increase in the crack path tortuosity. With more initial defects inside coal, a more obvious thermal damage degree and wider damage distribution will be induced by LN2 cooling, leading to more complicated crack formation paths and a higher fragmentation degree, such as that of lignite coal.

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The radial variation of the selected physical and mechanical properties of Norway spruce (Picea abies (L.) H. Karst) wood from the provenance area in Głuchów

Annals of WULS, Forestry and Wood Technology ◽

10.5604/01.3001.0013.7729 ◽

2019 ◽

Vol 105 ◽

pp. 133-143

Author(s):

KAROLINA ZAWADZKA ◽

PAWEŁ KOZAKIEWICZ

Keyword(s):

Mechanical Properties ◽

Picea Abies ◽

Norway Spruce ◽

Bending Strength ◽

Physical And Mechanical Properties ◽

Research Area ◽

Radial Variation ◽

Static Modulus ◽

Spruce Wood ◽

Static Modulus Of Elasticity

The radial variation of the selected physical and mechanical properties of Norway spruce (Picea abies (L.) H. Karst) wood from the provenance area in Głuchów. Spruce wood (Picea abies (L.) H. Karst) is one of the main species used in building constructions. Due to the wide occurrence, it is important to test various origins and in this way select those with the best material properties. Wood was obtained from one habitat from a provenance experimental area in Głuchów from 40-year-old trees. For the study, trees from three different origins were selected: Nowe Ramuki, Bliżyn and Rycerka Praszywka II (origin from respectively northern, central and southern Poland - seedlings came from these places). Spruce wood from Bliżyn, which is the closest to the proven research area in Głuchów, reached the highest average values in all studied traits (density, ultrasonic wave velocity, dynamic and static modulus of elasticity and static bending strength) and was characterized by the highest variability of these features. Regardless of the origin, the above-mentioned features of the wood showed a clear upward trend going from the pith to the to the side of the trunk.

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Influence Of Pressing Time On Physical And Mechanical Properties Of Particleboards Made From Scots Pine (Pinus sylvestris L.)

European Mechanical Science ◽

10.26701/ems.532796 ◽

2020 ◽

Vol 4 (2) ◽

pp. 78-81

Author(s):

Miglena VALYOVA ◽

Daniel KOYNOV

Keyword(s):

Mechanical Properties ◽

Pinus Sylvestris ◽

Scots Pine ◽

Physical And Mechanical Properties ◽

Pressing Time

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Comparative Assessment Of Some Physical And Mechanical Properties Of Wood Of Different Scots Pine Climatypes

Scientific Horizons ◽

10.48077/scihor.24(2).2021.27-36 ◽

2021 ◽

Vol 24 (2) ◽

pp. 27-36

Author(s):

Siarhei Rabko ◽

Aliaksandr Kozel ◽

Ivan Kimeichuk ◽

Vasyl Yukhnovskyi

Keyword(s):

Mechanical Properties ◽

Scots Pine ◽

Bending Strength ◽

Geographical Origin ◽

Testing Machine ◽

Physical And Mechanical Properties ◽

Forest Steppe ◽

Siberian Pine ◽

North Latitude

For a more efficient and rational use in the production of Scots pine wood of various geographical origin, it is necessary to know its physical and mechanical properties. The purpose of this study was to determine the physical and mechanical properties of wood of 17 climatic ecotypes of Scots pine and to carry out a comparative analysis of the indicators obtained for the studied climatypes separately and when they are grouped into subspecies in accordance with the classification of L.F. Pravdin. The range of the geographical origin of the places of seed procurement is from 47 to 62° north latitude and from 22 to 85° east longitude. The modern density universal testing machine MTS INSIGHT 100 was used for research. As a result of the research, it was found that the density of wood in an absolutely dry state varies from 370 kg/m3 (Kursk climatype) to 524 kg/m3 (Volgograd climatype), and at 12% humidity – from 397 kg/m3 (Kursk climatype) to 550 kg/m3 (Volgograd climatype). The index of the strength of wood of the studied climatypes for compression along the fibres was from 32 MPa (Kursk climatype) to 54 MPa (Volgograd climatype), and for static bending – from 55 to 92 MPa for the Vologda and Ulyanovsk climatypes, respectively. Distribution of Scots pine climatypes into subspecies in accordance with the classification of L.F. Pravdin and the obtained data on the physical and mechanical properties of wood have a certain pattern. The maximum density of wood at 12% moisture is typical for the European Scots pine subspecies is 497±8 kg/m3 , the minimum value of this indicator for the Siberian Scots pine subspecies is 423±30 kg/m3 . An intermediate position is occupied by the subspecies of Lapland pine and Forest-steppe pine with values of 483±16 and 464±12 kg/m3 , respectively. The strength index of wood in the studied subspecies for compression along the fibres ranged from 47±1 MPa (European subspecies) to 33±4 MPa (Siberian subspecies), in the Lapland pine subspecies – 44±2 MPa and somewhat lower in the Forest-steppe pine subspecies – 42±2 MPa. The maximum value of the static bending strength of wood is typical for the European pine subspecies – 78±4 MPa, and the minimum – for the Siberian pine subspecies – 61±14 MPa. This indicator turned out to be equal in subspecies of forest-steppe and Lapland pine and amounted to 72±4 MPa. The practical value of the work lies in identifying the existing differences and variability among climatypes according to the studied physical and mechanical properties of wood and selecting the most promising of them for further breeding purposes

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