Linden Wood Research Articles

The effect of moisture content over the fibre saturation points on the impact strength of wood.

The article's main aim is to assess the mechanical behaviour of linden under high-rate loadings (impact) and its change due to changes in moisture content (MC) over fibre saturation point. For assessing the mechanical properties of green wood, mainly the data of the dried wood is not applicable since the moisture content can drastically affect the mechanical properties of the wood. By testing both dried and high-moisture-content wood, we can understand a general viewpoint toward the effect of the moisture content on the impact behaviour of the wood. Several test samples were made of linden wood with different moisture content levels of 11%, 60% and 160%. A drop-weight impact machine tested the specimens to measure the reaction force of the hammer during a very short impact period. The results of the tests were parameters such as force-time chart, the maximum force required for crack initiation, the impact bending strength (IBS) and the work needed for crack initiation. The results indicated an increase in MC decreases the maximum force, work required for crack initiation and IBS drastically. However, when MC exceeded the fibre saturation point (FSP), there was no further influence on the force pattern and maximum required force.

Selected Mechanical and Physical Properties of Thermally Modified Wood after Field Exposure Tests

This study aimed to evaluate the impact of thermal modification on the physical and mechanical properties of three different wood species from Bosnia and Herzegovina, namely beech wood (Fagus sylvatica L.), linden wood (Tilia cordata), and silver fir wood (Abies alba). The samples underwent thermal modification at five different temperatures (170 °C, 180 °C, 195 °C, 210 °C, and 220 °C) for varying durations (ranging from 78 to 276 min). After treatment, they were exposed to outdoor conditions for twelve months. The study examined the four-point bending strength, tensile force, color change, and surface quality of the modified and unmodified samples. The results showed that outdoor exposure negatively impacted the mechanical properties of the unmodified samples, especially in the linden wood which was 41% and the beech wood which was 42%. Additionally, outdoor exposure caused significant surface cracks in the thermally modified linden and beech wood. The study also found prominent color changes in the modified and unmodified samples during twelve months of exposure. The roughness of the samples was determined with a confocal laser scanning microscope, which showed that the roughness increased on both the axial and the longitudinal surfaces after weathering. The highest roughness for the fir wood was determined to be 15.6 µm. Overall, this study demonstrates the importance of wood modification and its impact on the use-value of wood products.

Sensorium

Sensorium

Preservation and Restoration of an Old Wooden Icon with Complex Carved Ornaments, in a Conservation State of Precollapse

Wooden icons used in liturgical activities suffer a series of evolutionary deteriorations and degradations over time, due to improper storage and use conditions. The deterioration of the physical state of the structural-functional elements and degradation of the chemical nature of the components often lead old easel paintings to precarious preservation (almost close to pre-collapse), impossible to use or display as an artifact. In this study was included an old oil-painted icon on a carved linden wood support with fine gilded ornaments, which frames a central icon (“Coronation of Virgin Mary”) and a complex Menaion icon system with iconographic scenes. It was made by an anonymous author and dates back to the late 18th and early 19th centuries. As the icon has a special beauty and an ornamental and iconographic complexity, having a great heritage value, it required the elaboration of an optimal preservation–restoration protocol for the museum exhibition. Initially, the nature of the pictorial materials was determined, and their preservation state was evaluated using the OM, SEM-EDX, micro-FTIR methods, and CIE L*a*b* colorimetry and visible and UV reflectography were used in the evaluation of the wash test and in compatibility studies. Based on the data obtained, the optimal materials and procedures for structural reintegration were selected (including support fillings and filling of gaps), then chromatic reintegration and gilding, followed by final revarnishing, with or without patination additives.

Indentation Hardness and Elastic Recovery of Some Hardwood Species

The purpose of the study was to measure the Brinell hardness (HB) of six wood species and evaluate the ability to recover the depth of the imprint (self-re-deformation). Straight-grain clear samples of ash, beech, alder, birch, iroko, and linden wood were prepared. Measurements were made in the three main reference timber cross-sections: radial (R), tangential (T), and axial/longitudinal (L) and with two measuring loads of 30 kG and 100 kG (294.2 N and 980.7 N). The tested wood species could be classified into hard (ash, beech), medium-hard (alder, birch, iroko), and soft (linden) wood species. The HBs of each tested wood species differed in the cross-sections, i.e., side hardness (R, T) and end hardness (L). Higher HB values were obtained at 100 kG load in all species and all three cross-sections. The lowest influence of the measurement force value on the HB value was revealed for the soft wood species (linden: 107–118%). This influence was visible for the other five medium-hard and hard wood species, ranging from 125% to 176%. The percentage of temporary imprint in total imprint depth (x/H) varied from 12 to 33% (linden 12–18%—the lowest self-re-deformation ability; beech 25–33%—the highest self-re-deformation ability). The results of this study underline that the higher the density of the wood, the higher the Brinell hardness, and, simultaneously, the greater the measurement force used, the higher the Brinell hardness measured. The ability of self-re-deformation in wood’s R and T cross-sections depends on the wood density and the measuring force used. In contrast, this ability only depends on the wood density in the L cross-section. Those observations imply that the compaction of the cell structure during side compression is mainly non-destructive, while the longitudinal deformation of the cell structure (the buckling of cell walls and fracture of ends of the cells) is to a great degree destructive and irreversible. These results can be used in the construction and furniture sectors, especially when designing products and planning the woodworking of highly loaded wood floors and furniture elements.

Water absorption study and characterization of polymer composites developed from discarded nylon carpet

The scientific objective of this work is to reuse the polymer materials generated from carpet waste. The nylon obtained from the discarded carpet was used as reinforcement material into the epoxy matrix phase. A modified approach of Vacuum-assisted resin transfer molding (VARTM) was used to infuse the mixture of epoxy and hardener into the nylon carpet polymer composites. This investigates the water absorption behavior of carpet waste composite. It will justify the application of proposed composites for lightweight structural applications in a moisture environment. The nylon fiber-based-epoxy composite was dipped in water as per ASTM standard for a different duration, namely, 24, 48, 72, 144 hours. The findings demonstrate that it can effectively withstand in moisture environment, and a maximum 4.5% weight of samples increased among all the samples for a different duration. Also, the developed composite showed a lower water diffusion co-efficient than the nail head structure and linden wood. Also, the carpet waste composite samples were investigated for thermal degradation and chemical behavior using X-Ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, respectively. The finding shows that the proposed composite could be used for lightweight components such as dashboard panels, sound absorbers, panel sheets, wall tiles, etc.

Nectaronous and pollonous plants in forest plantations of the Middle Forest-Steppe of Prydniprovia

To provide the beekeeping industry with honey lands it is important to have a significant variety of natural and cultivated raw materials in a particular region. In this regard, promising honey products are artificial and natural forest plantations, which are widespread in the Middle Forest-Steppe of Prydniprovia, due to the significant participation of a wide range of honey plants. We primarily analyzed the participation of nectar- and pollen-bearing plants from the list of tree and shrub species of forest plantations in this area. For this purpose, forest management materials were used, the total area of forest plantations in this area is 251341.3 ha, of which 245209.7 ha (97.56%) are nectar- and pollen-bearing plants. Thus, Robinia pseudoacacia (26406.0 ha, 10.51%) and Tilia cordata (1868.8 ha, 0.74%) are the main raw material species of the forest-forming species, which includes 54 species of woody and shrubby honey plants. They provide the main productive honey harvest from natural honey plants. In addition, other species were found in the plantations (Pinus sylvestris (116592.9 ha, 46.39%), Quercus robur (60049.7 ha, 23.89%), Fraxinus excelsior (7835.5 ha, 3.12%) etc.), which can be sources of medical collection of small amounts of nectar and pollen. Forest plantations with available species of woody, shrubby and herbaceous plant species are valuable as raw materials for beekeeping. As a result of the analysis of the raw material value of forest lands by forest types in the ecological conditions of the Middle Forest-Steppe of Prydniprovia, out of 62 forest types distributed in the study area, 8 most valuable lands were identified. These include fresh hornbeam (32871.8 ha, 13.08%) and maple-linden oak wood (15144.4 ha, 6.03%), hornbeam oak wood (9034.3 ha, 3.71%), dry maple linden (12810.9 ha, 5.10%) and hornbeam (3585.2 ha, 1.43%) oak wood, fresh (2056.4 ha, 0.82%) and moist (1410.4 ha, 0.56%) linden-oak-pine sugrud, moist maple-linden oak wood (714.8 ha, 0.28%). This block of tree and shrub species of forest ecosystems does not take into account the phytodiversity of field protective forest strips of this area, but this complex of species is a promising source of nectar and pollen.

Comparison and Analysis of Radial and Tangential Bending of Softwood and Hardwood at Static and Dynamic Loading

This paper should primarily lead to a targeted expansion of the database dealing with bending characteristics, and thus help to understand the static and dynamic bending strength depending on the direction of external forces. Wood is very often used in the structural elements of buildings and wood products (e.g., furniture), in which there is both a static load, and in many cases a dynamic load, whilst the direction of loading is usually not considered. Specifically, the paper focuses on determining the bending strength and impact strength of seven economically-important wood species in the Czech Republic. The research includes not only the above-mentioned strength characteristics, but also the elastic characteristics, i.e., the static modulus of elasticity, and the dynamic modules of elasticity determined using the ultrasound and resonance methods. The procedure was methodologically in accordance with the valid harmonized standards or the usual methodological regulations. The most significant finding can be considered that the largest difference of the mean values of impact strength in the radial direction to the tangential direction was recorded for spruce wood, namely 50.3%. Slightly smaller differences were observed for larch wood, i.e., 41.2%. Minor differences of around 20% were recorded for beech, ash and oak wood. A difference with the opposite trend was recorded for birch wood rather than for the above-mentioned woods, namely −9.5%. Linden wood showed almost no difference (−0.8%). With regard to static bending strength, it was found that the largest difference (radial/tangential) was recorded for oak wood, i.e., 7.9%, while smaller differences were found for linden wood amounting to 6.6% and birch 4.7%. For spruce, larch, beech and ash wood, these differences are negligible. Another finding is that the dynamic modules of elasticity are greatly overestimated compared to static modules of elasticity. In the case of the examined wood of coniferous trees, these differences were up to a maximum of 20%. For wood of wood species with a diffuse-porous structure of wood, the differences were more pronounced, i.e., the range of 36% to 68%, and for wood species with a ring-porous structure in the range of 21% to 43%.

Mechanical properties and water absorption characteristics of composites reinforced with cotton fibres recovered from textile waste

The primary aim of this research is to develop thermoset composites reinforced with cotton fibres extracted from textile waste. These composites are mainly targeted to replace timber in its application for furniture items and in some visible and non-visible automotive components. The pre-consumer cotton textile wastes such as cutting waste, in garment manufacturing, and defective fabrics were converted into the fibrous form called ‘shoddy’, using rag-tearing technique. The fibrous web of shoddy was produced using the carding machine. This web was used for developing thermoset composites as a reinforcement material. The thermoset composites with four different fibre volume fraction values, namely 0.1, 0.2, 0.3 and 0.4 were developed using compression moulding technique. The developed composites were characterised by mechanical properties, dynamic mechanical properties, thermal degradation behaviour and water absorption behaviour. The mechanical properties of the composites were found comparable with that of commercial wood. These composites can be used to develop a dashboard panel. The composites developed in this research have shown low water diffusion coefficient values as compared with pine, oak and linden wood.

Characteristics of the surface chemistry of linden pyrochar after removal of labile organic matter

The changes of chemical properties of the pyrochar surface were studied in the laboratory experiment that simulated pedogenic transformation of pyrochar under the influence of soil biota. The native pyrochar samples were obtained by pyrolysis of linden wood residues at the temperature of 250°C, 450°C and 650°C. Their modified samples were obtained by removing an easily degradable pool of organic substances that can be used by microorganisms during the first months after application to the soil. In low-temperature linden pyrochar (250°C and 450°C) dominated carboxylic and phenolic surface groups, in high-temperature (650°C) - lactonic groups. After removal of readily decomposable organic substances the acidity of the phenolic and lactonic groups in pyrochar of low-temperature pyrolysis sharply decreased. Characteristic feature of all studied samples is the presence in IR spectra of absorption bands of gyroxyl, carbonyl, methylene groups and organosilicon polymers. The feature of IR spectra of linden pyrochar (250°C and 450°C) is the presence of absorption bands of the stretching vibrations of the tertiary alcohols and phenols C-O group.

Archaeometric and Chemometric Studies Involved in the Authentication of Old Heritage Artefacts II. Old linden and poplar wood put into work

The paper presents the results obtained in the study of new archaeometric and chemometric characteristics for old linden wood (Tillia cordata Mill.) and poplar wood (Populus robusta), put into work. Therefore, based on elemental chemical composition data, humidity, pH, ash and those related to wood extraction components, which are characteristics with low arteriometric potential, the chemometric characteristics with an archeometric value were evaluated. Samples used in this study, both linden and poplar wood, the following near-linear ratios were observed in the next reports: C/O, (C+H)/O, (C+H)/Norganic, pH/Humidity, Nmineral/Ash, extract in NaOH/extract in hot water and extract in ethyl alcohol/extract in ether, which can be used in establishing an archaeometric reference.

Comparison of moisture diffusion coefficients for pine, oak and linden wood

This article presents experimental research on the moisture diffusivity in wood within the range of hygroscopic moisture. This research was carried out on samples of three types of trees: Scots pine, small-leaved linden and pedunculate oak. It included measurements of kinetics of moisture adsorption within the range of air relative humidity from 25% to 85%. For each type of wood, the experiment was carried out with unidirectional flow of moisture, in each of the material principal orthotropic directions, by examining the diffusion coefficient along the fibres, in the tangential direction and in the radial direction. Values of moisture diffusion coefficients and mass surface emission coefficient were found with the use of method of minimizing the objective function, that is, by fitting the computational adsorption kinetics curves to the experimental ones. At the same time, three cases of variations of the moisture diffusion coefficient together with moisture content of the material have been analysed each time: in the form of a constant, linear function and a quadratic function, assuming a constant value of mass surface emission coefficient on the absorbing surface of samples. The performed calculations allowed determining whether the moisture diffusion coefficients have extreme values within the analysed range of moisture content and what is the impact of various diffusion mechanisms on the whole process of transferring moisture in the considered cases.

Optimization of Technical Parameters for Making Plant Fiber Composite Pencil Board Based on PSO-BP

Wood plastic composites (WPCs) were prepared and used as pencil board. The primary raw materials were corn straw fiber powder, high-density polyethylene, and polystyrene. The tensile strength, surface roughness, hardness, and roll cutting performance of the prepared composites were tested and compared with those of linden wood, which is typically used for pencil board. A back propagation (BP) neural network was adopted to build the prediction model of process technical parameters of the composite. An improved particle swarm (modified particle swarm optimizer, MPSO) was adopted to optimize the BP neural network, and the advantages of the PSO algorithm’s global optimization ability and the BP neural network algorithm’s high processing speed were realized. The results show that the composite had the best performance, with a mass ratio of 3.8 (corn straw fiber powder): 47.6 (high-density polyethylene): 28.6 (polystyrene). The composites can be used as a substitute for linden wood in the production of pencil board.

Fast Pyrolysis of Four Lignins from Different Isolation Processes Using Py-GC/MS

Pyrolysis is a promising approach that is being investigated to convert lignin into higher value products including biofuels and phenolic chemicals. In this study, fast pyrolysis of four types of lignin, including milled Amur linden wood lignin (MWL), enzymatic hydrolysis corn stover lignin (EHL), wheat straw alkali lignin (AL) and wheat straw sulfonate lignin (SL), were performed using pyrolysis gas-chromatography/mass spectrometry (Py-GC/MS). Thermogravimetric analysis (TGA) showed that the four lignins exhibited widely different thermolysis behaviors. The four lignins had similar functional groups according to the FTIR analysis. Syringyl, guaiacyl and p-hydroxyphenylpropane structural units were broken down during pyrolysis. Fast pyrolysis product distributions from the four lignins depended strongly on the lignin origin and isolation process. Phenols were the most abundant pyrolysis products from MWL, EHL and AL. However, SL produced a large number of furan compounds and sulfur compounds originating from kraft pulping. The effects of pyrolysis temperature and time on the product distributions from corn stover EHL were also studied. At 350 °C, EHL pyrolysis mainly produced acids and alcohols, while phenols became the main products at higher temperature. No obvious influence of pyrolysis time was observed on EHL pyrolysis product distributions.

Физико-механические показатели и режимы сушки древесины липы без искусственного увлажнения

The article describes the features of the process and conditions of drying without artificial humidification of uncut lumber of linden in convective drying chambers without artificial humidification for the manu-facture of furniture parts and joinery products. Methodology of the work, the size of the samples and the rules for their selection are described. The data of physical and mechanical properties of linden wood are given, such as density, number of annual rings and the percentage of late wood. Studies have been con-ducted at the Department of Mechanical Wood Technology of VSAFT and one of the real estate compa-nies of Voronezh.

Experimental investigation of pyrolysis process of woody biomass mixture

This paper describes an experimental investigation of pyrolysis of woody biomass mixture. The mixture consists of oak, beech, fir, cherry, walnut and linden wood chips with equal mass fractions. During the experiment, the sample mass inside the reactor was 10 g with a particle diameter of 5–10 mm. The sample in the reactor was heated in the temperature range of 24–650°C. Average sample heating rates in the reactor were 21, 30 and 54 °C/min. The sample mass before, during and after pyrolysis was determined using a digital scale. Experimental results of the sample mass change indicate that the highest yield of pyrolytic gas was achieved at the temperature slightly above 650°C and ranged from 77 to 85%, while char yield ranged from 15 to 23%. Heating rate has significant influence on the pyrolytic gas and char yields. It was determined that higher pyrolysis temperatures and heating rates induce higher yields of pyrolytic gas, while the char mass reduces. Condensation of pyrolytic gas at the end of the pyrolysis process at 650°C produced 2.4–2.72 g of liquid phase. The results obtained represent a starting basis for determining material and heat balance of pyrolysis process as well as woody biomass pyrolysis equipment.

Preparation and properties of porous, biomorphic, ceria ceramics for immobilization of Sr isotopes

Abstract A new technology for radionuclide trapping which is based on bio-templating approach was proposed in this paper. Porous oxide ceramics was prepared by wet impregnation of biological template with water solution of cerium and strontium nitrates. The template was derived from linden wood (tilia amurensis). Repeated pressure impregnation, heat treatments and final calcination at 1000 °C in air resulted in the template burnout and consolidation of the oxide layers. The obtained products had structure which corresponded to the negative replication of biological templates. X-ray diffraction, scanning electron microscopy, Raman spectroscopy and porosimetry were employed to characterize the composition and structure of biomorphic ceramics. It was found that the wood impregnated with water solution of cerium and strontium nitrates was converted into oxide ceramics (Ce0.9Sr0.1O2−δ), while preserving the microstructural features of the biological preform.

Cубстратні вподобання плевротоїдних грибів Харківського Лісостепу

Information on substrate preferences of pleurotoid fungi species revealed in Kharkiv Forest-Steppe is discussed. Seventeen identified species of fungi used as substrate 18 species of vascular plants, e. g. 17 – trees and shrubs, and 1 species ( Carex pilosa Scop.) – herbaceous plant. The main part of pleurotoid fungi used as substrate the wood of common aspen and pedunculate oak. Tilia spp. in Kharkiv Forest-Steppe is also appertain to the leading substrate-produce plants for a lot of pleurotoid fungi species. Most of specimens have been found on aspen, oak, and linden wood. Most of identified species had a wide range of substrates. Four species ( Pleurotus calyptratus, Resupinatus applicatus, Neolentinus lepideus and Tapinella panuoides ), on the contrary, have been characterized by a narrow substrate preferences. Based on data about the size of pleurotoid’s substrates, an importance of conservation of large-scale dead wood to maintain diversity of pleurotoid fungi has been shown. Most of pleurotoid species, as well as the specimens of fruit bodies, had been found on substrates with the diameter more than 20 cm. Keywords: pleurotoid fungi, Kharkiv Forest-Steppe, dead wood.

Mechanical properties of biomorphic silicon carbide ceramics

Biomorphous ?-SiC ceramics were produced from linden wood by impregnation with tetraethyl orthosilicate (TEOS), followed pyrolysis and high temperature treatment at 1580?C. Six specimen groups included charcoal and five groups with different number of impregnation were analyzed. Flexural and compressional strength of charcoal and woodlike SiC ceramic were characterized using three-point and compression testing. Mechanicall properties increased slightly with number of impregnation cycles. Ultrasonic pulse velocity testing (UPVT) was used to determine dynamic young modulus of elasticity. Laser surface modification was studied by interaction with Nd:YAG laser, operating at 1064 or 532 nm wavelengthss and pulse duration of 150 ps.

Saint Peter in the folk religion of the Romanians

St. Peter has taken a priviliged place in Romanian popular religion. His birth was miraculous: his mother became pregnant, even though she was too old to have children, after having eaten an apple. He refused to be born until he was promised a fairy as his wife. He marries, becomes emperor for fifty years, but after the death of his wife, he becomes an eremite by the Jordan River. From there, he was taken by God to heaven. He can be seen together with the apostle St. Paul on the moon. He was given the keys to heaven and does not permit the entrance of sinners. He even denies entry to his own parents. He was a companion, servant, and adviser of the Lord on Earth as an old man wearing sandals of iron or of linden wood. He makes the mistakes of a common man: he wants to perform miracles but cannot; he decapitates a devil and a woman, but when he tries to correct his mistake, he puts the head of the devil on the woman’s shoulders and vice versa; he divulges a secret told to him by God; he goes to hell and does not return in time; he loses the keys to heaven; he enjoys alcohol, food, and tobacco. He is celebrated on January 16th and June 29th. He is the master of the animals, in particular wolves to whom he gives food on January 16th. For this reason there is a need for a study on the role of St. Peter in all European mythology.