Density, hardness and strength properties of densified fir and aspen woods pretreated with water repellents

AbstractIn this study, the effect of thermo-mechanical densification on the density, hardness, compression strength, bending strength (MOR), and modulus of elasticity (MOE) of fir and aspen wood pretreated with water repellents was analyzed. Wood specimens were impregnated with paraffin, linseed oil and styrene after pre-vacuum treatment. Then, the impregnated wood specimens were densified with compression ratios of 20 and 40%, and at 120, 150 and 180 °C. The results indicated that the density, hardness and strength properties of the all densified specimens (untreated and impregnated) increased depending on the compression ratio and temperature. For all tested properties, higher increases were obtained in the paraffin and styrene pretreated specimens compared to untreated samples. However, the increase rates in linseed oil pretreated specimens were generally lower than untreated specimens. Regarding water repellents the most successful results in all tested properties were determined in styrene pretreated specimens. The density, hardness and strength properties of all specimens increased with the increase in compression ratio. On the other hand, the increase in the compression temperature negatively affects the properties of untreated and linseed oil pretreated specimens, while having a generally positive effect on the properties of paraffin pretreated specimens. However, all tested properties of styrene pretreated specimens have increased significantly due to the increase in compression temperature. The increasing strength properties of wood as a result of densification have increased much more with paraffin and especially styrene pretreatment. These combinations can be considered as an important potential for applications that require more hardness and strength.

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The modification of an epoxy resin by natural plant materials

Ochrona Srodowiska i Zasobów Naturalnych ◽

10.2478/oszn-2020-0003 ◽

2020 ◽

Vol 31 (1) ◽

pp. 14-20

Author(s):

Joanna Masiewicz ◽

Martyna Roszowska-Jarosz ◽

Marcin Kostrzewa ◽

Aleksandra Jasik ◽

Paulina Krawczyk

Keyword(s):

Epoxy Resin ◽

Bending Strength ◽

Strength Properties ◽

Critical Stress Intensity Factor ◽

Plant Materials ◽

Three Point Bending ◽

Hemp Fibres ◽

Protection Cost ◽

Positive Effect ◽

Properties Of Composites

Abstract The article presents the results of research on the modification of Epidian 5 epoxy resin by introducing natural modifiers. It's easy accessibility and biodegradability has a positive effect on environmental protection, cost-effectiveness of the process, useful and strength properties of composites. Still looking for the best solutions in the production of epoxy composites combining these features, we have attempted to compare and select the most optimal natural modifier. The epoxy resin was modified with collagen, hemp fibres, cellulose from pepper extraction residues. The amount of amine hardener suggested by the manufacturer was added to the composition. Each composition was cured at room temperature for 24 hours and then cured at 80°C for 3 hours. The prepared composites were subjected to impact assessment additions for mechanical properties, impact strength, three-point bending strength, critical stress intensity factor and gel time.

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Effect of Water Repellents on Hygroscopicity and Dimensional Stability of Densified Fir and Aspen Woods

Drvna industrija ◽

10.5552/drvind.2020.1901 ◽

2020 ◽

Vol 71 (1) ◽

pp. 29-40

Author(s):

Huseyin Pelit ◽

Fatih Emiroglu

Keyword(s):

High Temperature ◽

Dimensional Stability ◽

Atmospheric Pressure ◽

Linseed Oil ◽

Vacuum Treatment ◽

Densified Wood ◽

Water Repellent ◽

Compression Rate ◽

Thickness Swelling ◽

Water Repellents

This study investigated the effect of pre-impregnation with water-repellent agents on the hygroscopicity and dimensional stability of fir (Abies bornmulleriana Mattf.) and aspen (Populus tremula L.) woods. After pre-vacuum treatment, the samples were impregnated at atmospheric pressure with paraffin, linseed oil and styrene, and then densified at compression rates of 20 % and 40 % at 120, 150 and 180 °C. The results showed that water repellents significantly affected the hygroscopicity and dimensional stability of the densified wood samples. Compression recovery rate (CRR), thickness swelling (TS), equilibrium moisture content (EMC), and water absorption (WA) values of the densified samples decreased with impregnation pretreatments. The linseed oil treatment gave more positive CRR and TS results than paraffin. Lower EMC and WA values were found in the paraffin-treated samples. However, the most successful results for all tested properties were determined in the styrene pretreated samples in which hygroscopicity decreased and dimensional stability increased (especially for aspen) due to increases in the compression rate and temperature related to densification conditions. In the styrene pretreated samples, the high temperature (180 °C) and compression rate (40 %) significantly reduced CRR, TS, EMC and WA, total dimensional stability was nearly achieved and the water repellent effectiveness was close to 100 %.

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Utilization of Birch Bark as an Eco-Friendly Filler in Urea-Formaldehyde Adhesives for Plywood Manufacturing

Polymers ◽

10.3390/polym13040511 ◽

2021 ◽

Vol 13 (4) ◽

pp. 511

Author(s):

Roman Réh ◽

Ľuboš Krišťák ◽

Ján Sedliačik ◽

Pavlo Bekhta ◽

Monika Božiková ◽

...

Keyword(s):

Bending Strength ◽

Urea Formaldehyde ◽

Formaldehyde Emission ◽

Birch Bark ◽

Gravimetric Analysis ◽

European Standard ◽

Scanning Calorimetry ◽

Wood Processing ◽

Fagus Sylvatica L ◽

Positive Effect

The potential of using ground birch (Betula verrucosa Ehrh.) bark as an eco-friendly additive in urea-formaldehyde (UF) adhesives for plywood manufacturing was investigated in this work. Five-ply plywood panels were fabricated in the laboratory from beech (Fagus sylvatica L.) veneers bonded with UF adhesive formulations comprising three addition levels of birch bark (BB) as a filler (10%, 15%, and 20%). Two UF resin formulations filled with 10% and 20% wheat flour (WF) were used as reference samples. The mechanical properties (bending strength, modulus of elasticity and shear strength) of the laboratory-fabricated plywood panels, bonded with the addition of BB in the adhesive mixture, were evaluated and compared with the European standard requirements (EN 310 and EN 314-2). The mechanical strength of the plywood with the addition of BB in the adhesive mixture is acceptable and met the European standard requirements. Markedly, the positive effect of BB in the UF adhesive mixture on the reduction of formaldehyde emission from plywood panels was also confirmed. Initially, the most significant decrease in formaldehyde release (up to 14%) was measured for the plywood sample, produced with 15% BB. After four weeks, the decrease in formaldehyde was estimated up to 51% for the sample manufactured with 20% BB. The performed differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and derivative thermogravimetry (DTG), also confirmed the findings of the study. As this research demonstrated, BB as a waste or by-product of wood processing industry, can be efficiently utilized as an environmentally friendly, inexpensive alternative to WF as a filler in UF adhesive formulations for plywood manufacturing.

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Study on Particleboard made from Nipa palm (Nypa fruticans) stem wood and Rajkoroi (Albizia richardiana) wood

Journal of Non Timber Forest Products ◽

10.54207/bsmps2000-2018-qpjp02 ◽

2018 ◽

Vol 25 (1) ◽

pp. 15-18

Author(s):

Md. Mahabubur Rahaman ◽

◽

Khurshid Akhter ◽

S. Hossain ◽

Md. Rakibul Islam ◽

...

Keyword(s):

Tensile Strength ◽

Dimensional Stability ◽

Bending Strength ◽

Strength Properties ◽

Wood Chips ◽

Standard Specification ◽

Stem Wood ◽

Nypa Fruticans ◽

Albizia Richardiana ◽

Nipa Palm

The study was conducted to find out the suitability of making particleboard using nipa palm (Nypa fruticans) stem wood and rajkoroi (Albizia richardiana) wood chips. Particleboards were fabricated at six different ratios of nipa palm stem and rajkoroi wood chips such as 100:0, 75:25, 50:50, 25:75, 10:90 and 0:100. Characteristics of particleboards such as modulus of rupture, internal bond strength, water absorption, thickness swelling and moisture content were measured. Results shows that particleboards made from 100% rajkoroi wood chips have the highest static bending properties and highest tensile strength properties of other particleboards but 100% nipa palm stem wood chips have the lowest static bending and lowest tensile strength properties of other particleboards. 10% nipa palm stem wood chips particleboard have the highest bending strength and tensile strength is better than 100% nipa palm stem wood chips and other mixing chips of particleboards. Mechanical, water resistance and dimensional stability properties were tested according to Indian standard specification. Tensile strength passed the British and German standard specification and nearest to Bureau of Indian Standard, bending strength was found nearest to Indian Standard but lower than German and British Standard specification. Strength property of rajkoroi wood chips particleboard is higher than nipa palm steam wood chips particleboard but dimensional stability is lower than nipa palm steam wood chips particleboard.

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Machine of testing the ceramic’s bending strength properties at high temperature and ultra-low speed

Frontiers of Mechanical Engineering in China ◽

10.1007/s11465-010-0094-x ◽

2010 ◽

Vol 5 (3) ◽

pp. 289-293

Author(s):

Jianhui Zhang ◽

Onuki Akiyoshi ◽

Fang Ye

Keyword(s):

High Temperature ◽

Bending Strength ◽

Strength Properties ◽

Low Speed

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Influence of Linseed Oil Varnish Admixture on Glauconite Clay Mortar Properties

Materials ◽

10.3390/ma13235487 ◽

2020 ◽

Vol 13 (23) ◽

pp. 5487

Author(s):

Przemysław Brzyski ◽

Magdalena Grudzińska

Keyword(s):

Compressive Strength ◽

Flexural Strength ◽

Mechanical Strength ◽

Water Resistance ◽

Linseed Oil ◽

Sorption Properties ◽

Vapor Permeability ◽

Research Results ◽

Positive Effect

Raw clay is used nowadays in construction as a component of mortars and plasters and as a binder in composites based on straw or shives. It is a material with good sorption properties and vapor permeability, but it is susceptible to shrinkage, is not resistant to water, and also is characterized by low mechanical strength, which makes it impossible to be used, for example, in external plasters. Various additives and admixtures are used to improve selected properties of clay mortars. The article presents the research results and assessment of the effect of glauconite clay mortar modification with an admixture of linseed oil varnish on selected properties. Admixtures in the amounts of 1%, 2%, and 3% in relation to clay weight were used. Flexural and compressive strength, water resistance, shrinkage, drying capacity, density, and porosity of mortar, were tested. The admixture of linseed oil varnish in the amounts used in the investigation had a positive effect on some of the tested properties; regardless of the quantity of the admixture, the modified mortars had better parameters concerning flexural strength, shrinkage reduction, and water resistance than the reference mortar, without admixture.

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A Comparison of the Loading Direction for Bending Strength with Different Wood Measurement Surfaces Using Near-Infrared Spectroscopy

Forests ◽

10.3390/f11060644 ◽

2020 ◽

Vol 11 (6) ◽

pp. 644 ◽

Cited By ~ 2

Author(s):

Yohei Kurata

Keyword(s):

Near Infrared ◽

Bending Strength ◽

Tensile Force ◽

Strength Properties ◽

Bending Test ◽

Tangential Section ◽

Compression Force ◽

Radial Section ◽

Loading Direction ◽

Light Acquisition

Wood is widely used throughout society for building resources and paper. To further expand wood’s use in the wood industry, we tested the bending strength properties of wood and certified its internal quality by using near-infrared spectroscopy (NIRS). In this study, the relationship between bending strength and loading direction was compared by changing the light acquisition point of wood surfaces to elucidate the anisotropy of the wood using NIRS. The two loading directions were defined by using a bending test as the radial section and the tangential section. Two light acquisition points with NIRS were also defined by a bending test as the loading position (the compression surface) and the opposite surface (the tensile surface), and a comparison was made between the prediction accuracy of the wood’s mechanical strength properties obtained via a bending test using two pieces of light acquisition data. The strength properties of the wood bending tests were the elastic modulus in bending (Eb), the bending strength (Fb) and density (DEN). Cryptomeria japonica was prepared and cut into a final size of 20 mm × 20 mm × 320 mm. Near-infrared (NIR) spectra were obtained from the compression force side and the tensile force side (calculating these averages), and a partial-least-squares regression (PLSR) was performed for the regression analysis. In the NIR measurement position, the best calibration results of the PLSR were the averaged data between the side undergoing the compression force and that undergoing the tensile force. Comparing the two loading directions, the result for the radial section was slightly superior to that of the tangential section. The radial section showed a good relationship between the spectra acquisition position and the arrangement of the wood’s structure. The estimation accuracy of bending strength properties differed depending on the location where the NIR spectra acquisition was performed.

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Influence of Site Conditions and Quality of Birch Wood on Its Properties and Utilization after Heat Treatment. Part I—Elastic and Strength Properties, Relationship to Water and Dimensional Stability

Forests ◽

10.3390/f10020189 ◽

2019 ◽

Vol 10 (2) ◽

pp. 189 ◽

Cited By ~ 4

Author(s):

Vlastimil Borůvka ◽

Roman Dudík ◽

Aleš Zeidler ◽

Tomáš Holeček

Keyword(s):

Heat Treatment ◽

Dimensional Stability ◽

Bending Strength ◽

Color Change ◽

Untreated Wood ◽

Strength Properties ◽

Treatment Temperature ◽

Impact Bending ◽

The Impact

This work deals with the quality of birch (Betula pendula) wood from different sites and the impact of heat treatment on it. Two degrees of heat treatment were used, 170 °C and 190 °C. The resulting property values were compared with reference to untreated wood samples. These values were wood density, compressive strength, modulus of elasticity (MOE), bending strength (MOR), impact bending strength (toughness), hardness, swelling, limit of hygroscopicity, moisture content and color change. It was supposed that an increase in heat-treatment temperature could reduce strength properties and, adversely, lead to better shape and dimensional stability, which was confirmed by experiments. It was also shown that the properties of the wood before treatment affected their condition after heat treatment, and that the characteristic values and variability of birch properties from 4 sites, 8 stems totally, were reflected in the properties of the heat-treated wood. Values of static MOR were the exception, where the quality of the input wood was less significant at a higher temperature, and this was even more significant in impact bending strength, where it manifested at a lower temperature degree. Impact bending strength also proved to be significantly negatively affected by heat treatment, about 48% at 170 °C, and up to 67% at 190 °C. On the contrary, the most positive results were the MOE and hardness increases at 170 °C by about 30% and about 21%, respectively, with a decrease in swelling at 190 °C by about 31%. On the basis of color change and other ascertained properties, there is a possibility that, after suitable heat treatment, birch could replace other woods (e.g., beech) for certain specific purposes, particularly in the furniture industry.

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Analysis on Microstructure and Mechanical Properties of Birch Laminated Veneer Lumber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.113-116.2035 ◽

2010 ◽

Vol 113-116 ◽

pp. 2035-2038

Author(s):

Bing Xue ◽

Ying Cheng Hu

Keyword(s):

Compression Ratio ◽

Bending Strength ◽

Longitudinal Vibration ◽

Flexural Vibration ◽

Bending Test ◽

Vertical Load ◽

Transmission Method ◽

Vibration Method ◽

Laminated Veneer Lumber ◽

Betula Platyphylla Suk

In this paper, four different nondestructive testing (NDT) methods and the static bending test were conducted on the birch (Betula platyphylla Suk.) laminated veneer lumber (LVL). The NDT methods included the longitudinal transmission method, longitudinal vibration method, in-plane and out-plane flexural vibration method. The effects of the compression ratio on the static bending (MOE) and bending strength (MOR) of LVL with vertical load were investigated. There were four compression ratios for different ply numbers of LVL, 8.1% for eight-ply samples, 18.3% for nine-ply samples, 26.5% for ten-ply samples, 33.1% for eleven-ply samples, respectively. The microscopic structure of the LVL was analyzed with a scanning electron microscope (SEM). The results showed that the MOE and MOR of LVL were increased with increasing compression ratio, and there was a strong correlation between each dynamic Young’s modulus and the static MOE.

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