scholarly journals Impact of cyclic densification on bending strength and modulus of elasticity of wood from temperate and tropical zones

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2869-2881
Author(s):  
Agnieszka Laskowska
Keyword(s):  
Modulus Of Elasticity ◽  
Mechanical Treatment ◽  
Bending Strength ◽  
Negative Impact ◽  
Modulus Of Rupture ◽  
Oak Wood ◽  
Densification Temperature ◽  
Before And After ◽  
Thermo Mechanical Treatment ◽  
Milicia Excelsa

Oak (Quercus robur L.), iroko (Milicia excelsa (Welw.) C.C. Berg), and tauari (Couratari spp.) wood were subjected to cyclic thermo-mechanical treatment (CTMT). The densification temperature amounted to 100 °C or 150 °C. The greatest changes in the modulus of rupture (MOR) value of the iroko wood, depending on the number of thermo-mechanical modification cycles, were noted. The MOR of the iroko wood, densified at 100 °C or 150 °C, after second thermo-mechanical modification cycle was twice as high as before the modification. No significant differences were observed between the modulus of elasticity (MOE) of oak wood before and after one modification cycle. Similar dependencies were noted in iroko wood. The thermo-mechanical modification performed over two cycles led to the highest increase, by about 56%, in MOE in oak wood densified at 150 °C. It was demonstrated that modification at 150 °C had a negative impact on iroko wood, which was manifested in the lower compression ratio of iroko at 150 °C than at 100 °C.

Research on the Bending Properties of the Bamboo-Wood Container Flooring

2013 ◽  
Vol 744 ◽  
pp. 366-369
Author(s):  
Juan Wei ◽  
Dan Zeng ◽  
Ming Jie Guan
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Accelerated Aging ◽  
Modulus Of Rupture ◽  
Bending Properties ◽  
Before And After ◽  
Aging Performance

In this paper, the bending properties of bamboo-wood container flooring and bamboo curtain-OSB container flooring were tested and the six-cycle artificial accelerated aging method of ASTM D1037 was conducted to evaluate the aging performance of two kinds of bamboo-wood container floorings. The modulus of rupture (MOR) and modulus of elasticity (MOE) were tested in the longitudinal and transverse directions before and after aging. The results showed that both the bending strength and MOE decreased after aging. The retention ratios of MOR of the bamboo-wood container flooring and bamboo curtain-OSB container flooring were respectively 43.5%, 72.0%, and the retention ratios of MOE were 54.6%, 76.3%. In general, the effect of aging on the bamboo-wood container flooring was larger than that on the bamboo curtain-OSB container flooring.

scholarly journals EFFECT OF THERMO-MECHANICAL TREATMENT ON PROPERTIES OF PARICA PLYWOODS (Schizolobium amazonicum Huber ex Ducke)

2017 ◽  
Vol 41 (1) ◽  
Author(s):  
Mírian de Almeida Costa ◽  
Cláudio Henrique Soares Del Menezzi
Keyword(s):  
Mechanical Properties ◽  
Mechanical Treatment ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Modulus Of Rupture ◽  
Thermal Treatments ◽  
Mechanical Compression ◽  
Specific Mass ◽  
Thermo Mechanical Treatment ◽  
Temperature And Pressure

ABSTRACT Thermo-mechanical treatment is a technique for wood modification in which samples are densified by means of heat and mechanical compression, applied perpendicularly to fibers, which under different combinations of time, temperature, and pressure increases wood density and thus improve some of its properties. This study aimed to treat thermo-mechanically parica plywood and observe the effects on its physical and mechanical properties. Specimens were submitted to two treatments, 120 and 150 ºC, remaining under pressure for seven minutes and, subsequently, under zero pressure for 15 minutes. Results showed a significant increase in specific mass from 0.48 g cm-3 to an average of 0.56 g cm-3, and a compression ratio of about 31.7% on average. Physical properties also varied significantly and results showed that treated samples swelled and absorbed more water than those untreated, leading to a greater thickness non-return rate. This indicates the proposed thermal treatments did not release the internal compressive stress generated during panel pressing, not improving its dimensional stability as a result. On the other hand, mechanical properties were positively affected, leading to an increase of 27.5% and 51.8% in modulus of rupture after treatments at 120 and 150 ºC, respectively. Modulus of elasticity and glue-line shear strength did not vary statistically and Janka hardness was 29.7% higher after treatment at 150 ºC.

scholarly journals Effects of thermo-hydro-mechanical treatments on various physical and mechanical properties of poplar (Populus) wood

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 9596-9610
Author(s):  
Yali Shao ◽  
Lili Li ◽  
Zhangjing Chen ◽  
Sunguo Wang ◽  
Ximing Wang
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Modulus Of Elasticity ◽  
Mechanical Treatment ◽  
Elasticity Modulus ◽  
Physical And Mechanical Properties ◽  
Modulus Of Rupture ◽  
Compression Rate ◽  
Thickness Swelling ◽  
Maximum Thickness

Poplar (Populus) wood was subjected in this work to thermo-hydro-mechanical treatment. The influence of the treatment parameters on the physical and mechanical properties were investigated. The wood samples were densified under three compression ratios (0%, 30%, and 50%), and thermally treated at three temperatures (180 °C, 200 °C, and 220 °C), at three thermal treatment durations (3 h, 4 h, and 5 h). The density, modulus of elasticity, modulus of rupture, radial hardness, and thickness swelling were measured. The results showed that the densities of the samples increased by 36.6% to 49.7%. As the compression rate increased, the temperature, duration, modulus of elasticity, modulus of rupture, and hardness increased. However, the dimensions of the densified samples were less stable. Compared to the densified samples, the maximum thickness swelling could be reduced by 74% (from 29.7% to 7.8%) when subjected to a thermal treatment at 220 °C for 3 h.

scholarly journals Impact of stone ground ‘V-fines’ dispersion and compatibilization on polyethylene wood plastic composites

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 6561-6575
Author(s):  
Kirsi Immonen ◽  
Erkki Saharinen ◽  
Ilkka Nurminen ◽  
Jari Sirviö ◽  
David Sandquist
Keyword(s):  
Tensile Strength ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
Negative Impact ◽  
Modulus Of Rupture ◽  
Pulp Fibers ◽  
Mechanical Pulp ◽  
Elongation At Break ◽  
Plastic Composites ◽  
Dispersing Agent

Recent studies have suggested that blocky mechanical pulp fines (CTMP fines) and fibrillar fines (SMC fines) have a negative impact on biocomposite modulus of rupture (MoR) in compression molded biocomposites. In addition, it was suggested that CTMP fines also have a negative impact on biocomposite modulus of elasticity (MoE). This study investigated whether these findings transfer to other types of cellulose fines material and injection molding. The effect of ‘V-fines’ addition to sawdust- and TMP-based biocomposites was analyzed, with respect to fines concentration, dispersing agent, and compatibilizers. The results indicated that the addition of ‘V-fines’ increased the stiffness (MoE) of all the analyzed compositions, while reducing the elongation at break. The addition of ‘V-fines’ reduced the tensile and flexural strength of TMP biocomposites, while it was largely unaffected for sawdust biocomposites. Flexural strength for neat ‘V-fines’ composites showed an increase that was proportional to the remaining pulp fibers composition. The addition of a dispersant agent to the ‘V-fines’ increased tensile strength, suggesting that an increased dispersion of the ‘V-fines’ can be achieved and is beneficial to the composite. The effects of the analyzed compatibilizer (polyethyleneoxide) was negligible, except for a small indication of increased MoE for fines / sawdust biocomposites.

Properties of orchard pruning and suitability for composite production

2013 ◽  
Vol 20 (4) ◽  
pp. 337-342 ◽  
Author(s):  
Halil Turgut Sahin ◽  
Mustafa Burak Arslan
Keyword(s):  
Modulus Of Elasticity ◽  
Internal Bond ◽  
Bending Strength ◽  
Lignin Content ◽  
Chemical Constituents ◽  
General Purpose ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Surface Strength ◽  
Board Type

AbstractApple and cherry pruning with red pinewood particles in various proportions were used as the raw material for the experimental particleboard manufacturing in laboratory conditions. The results showed that there were no considerable differences in the main chemical constituents of carbohydrate and lignin content, although there were some differences found for extractives that are considerably higher for both cherry and apple pruning. The mean modulus of rupture values of boards were found to ranged from 12.4 to 18.48 MPa. These indicated that all the boards, except for the board type F (prepared from 100% apple pruning), met the minimum bending strength required in standard for general-purpose particleboards. The modulus of elasticity and internal bond of the experimental particleboards usually decreased as red pinewood particle content decreases in proportion. However, all the boards produced in this study met the minimum modulus of elasticity, internal bond, and surface strength required in standard for general-purpose particleboards. However, the thickness swelling for 24 h was considerably higher than the required in standard value of 14% for all boards.

Mechanical properties of Ficus vallis-choudae (Delile), a lesser utilized species in Nigeria

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 6550-6560
Author(s):  
Lawrence Aguda ◽  
Babatunde Ajayi ◽  
Sylvester Areghan ◽  
Yetunde Olayiwola ◽  
Aina Kehinde ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
High Strength ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Impact Bending ◽  
Timber Market

Declining availability of the prime economic species in the Nigerian timber market has led to the introduction of Lesser-Used Species (LUS) as alternatives. Their acceptability demands information on the technical properties of their wood. The aim of this study was to investigate the mechanical properties of Ficus vallis-choudae to determine its potential for timber. Three mature Ficus vallis-choudae trees were selected and harvested from a free forest area in Ibadan, Oyo State, Nigeria. Samples were collected from the base (10%), middle (50%), and top (90%) along the sampling heights of each tree, which was further partitioned into innerwood, centrewood, and outerwood across the sampling radial position. Investigations were carried out to determine the age, density, moisture content, impact strength, modulus of elasticity, modulus of rupture, compressive strength parallel-to-grain, and shear strength parallel-to-grain. The mean impact bending strength, modulus of rupture, modulus of elasticity, maximum shear strength parallel-to-grain, and maximum compression strength parallel-to-grain for Ficus vallis-choudae at 12% moisture content were 20.4 N/mm2, 85.8 N/mm2, 709 N/mm2, 10.7 N/mm2, and 33.6 N/mm2, respectively. The study found the species to be dense with high strength properties in comparison with well-known timbers used for constructional purposes.

scholarly journals Use of Hardwood Species (Robinia pseudoaccacia from Short-rotation Plantations as Raw Material in Particleboards

2020 ◽  
Vol 9 (2) ◽  
pp. 18
Author(s):  
J. Lawrence Tene Tayo ◽  
Achale Travolta Achale ◽  
Markus Euring
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Black Locust ◽  
Coniferous Forest ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Internal Bonding ◽  
Mixed Stands ◽  
Swelling Properties ◽  
Short Rotation

The problem of climate change, coupled to the propagation of wood diseases (bark beetles for example), is leading to a shortage in softwood supply for the particleboard industries. Furthermore, the recent changes in the German forest policies which promote the conversion of coniferous forest into mixed stands are likely to enhance this phenomenon. There is, therefore, a growing need for research on possibilities of substituting the softwood with hardwood and other alternative material. For the first time, young six to seven years old Black locust (Robinia pseudoaccacia) stems from a short-rotation plantation were used at a laboratory scale with the objective of assessing the suitability of particleboard production. Four different variants were produced using different resin types: UF K350, UF K340, albumin, and PMDI, with a target density and thickness of 650 kg/m3 and 20 mm respectively for each board. The boards were tested regarding their mechanical (modulus of rupture, modulus of elasticity and internal bonding), physical (water absorption and thickness swelling) properties according to the European standard (EN 310, EN 317 and EN 319), and their formaldehyde content and emission following the EN 120 and EN 717. Industrial particles were used as reference material for the purpose of comparison. Promising bending strength was obtained with UF resins-bonded boards. The modulus of elasticity of all four variants fulfilled the EN 2003 requirements. The internal bond of the UF resins-bonded boards also met the general product standard, with values above 0.35 N/mm2. The bending strength and the internal bonding strength properties of the UF-bonded boards were superior to that of the reference boards produced with the industrial particles. Based on these results, black locust is a potential substitute for softwood in particleboard production and can be used in the industry as alternative raw material for panel production.

scholarly journals The effects of wood species, load direction, and adhesives on bending properties of laminated veneer lumber

BioResources ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. 3104-3112 ◽  
Author(s):  
Bekir Cihad Bal ◽  
İbrahim Bektaş
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Phenol Formaldehyde ◽  
Urea Formaldehyde ◽  
Eucalyptus Grandis ◽  
Variance Analysis ◽  
Modulus Of Rupture ◽  
Bending Properties ◽  
Laminated Veneer Lumber ◽  
Specific Modulus

In this study, the bending strength and stiffness of laminated veneer lumber (LVL) produced from beech (Fagus orientalis L.), poplar (Populus x euramericana I-214), and eucalyptus (Eucalyptus grandis W. Hill ex Maiden) wood using urea formaldehyde (UF), melamine urea formaldehyde (MUF), and phenol formaldehyde (PF) adhesives were determined. The tests were conducted in the flatwise and edgewise directions. The modulus of rupture (MOR), modulus of elasticity (MOE), specific modulus of rupture (SMOR), and specific modulus of elasticity (SMOE) were calculated. Variance analysis of the bending properties indicated that the effects of the species of tree, the direction of the load, and the type of adhesive were statistically significant. However, according to variance analysis of the SMOR, the effects of the type of adhesive were not significant. The results showed that the type of adhesive did not influence the bending properties of laminated veneer lumber. It can be stated that the differences among groups were due to differences in their densities. The direction of the load and the species of the tree had significant effects on the bending properties.

scholarly journals Chestnut: from coppice to structural timber. The case study of "Uso Fiume" beams sampled in Liguria

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Marco Togni ◽  
Alberto Cavalli ◽  
Davide Mannozzi
Keyword(s):  
Moisture Content ◽  
Cross Section ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Mechanical Tests ◽  
Modulus Of Rupture ◽  
Actual Condition ◽  
Assessment Procedure ◽  
Structural Element ◽  
Full Cross Section

<p>Recently Agriculture Department of Liguria Region had supported studies and researches on the timber quality of living trees in local coppice chestnut forests, with the prospect to produce also timber for structural use. Under some ad-hoc funds a 30 years old coppice forest in the high Bormida Valley, never thinned after the last utilization, has been chosen for sampling. 18 selected trunks were felled and the assortment called “Uso Fiume” (UF) was chosen, getting 49 beams (cross-section from 12¥12 to 24¥24 cm), by way of saw-mill operations The UF-beam is a structural element, derived from Italian tradition. Such elements are used in Italian buildings over the time, in substitution to structural sawn timber, principally for roofing. The UF-beam is a square edged log with wane; more precisely it is a full log, edged on four sides, maintaining boxed heart and an approximately central pith. Today the features of such a beam is established according to the specific Italian standard UNI 11035-3 for spruce and fir and to the CUAP (Common Understanding of Assessment Procedure) n. 03.24/22 for chestnut and conifers. The beams were visually graded according to the Visual Strength Grading procedure and the physical and mechanical properties (density, modulus of elasticity-MOE and modulus of rupture- MOR) were determined according to the standard requirements (EN 408, EN 384, ISO 3131), disregarding the moisture content: the mechanical tests were performed with wood in green state (moisture content M.C.&gt;30%) because it is the actual condition of use in building, due to the very low permeability of the chestnut heartwood which entails long seasoning time of large cross section beams. The study showed very high yields considering the stems-to-beams volume ratio, close to 70%. Characteristics values of the sample resulted: char. density 􀀀 􀀀􀀀kg/m³, char. modulus of elasticity E0,mean 10,3 GPa and char. bending strength fm,k 28,5 MPa. These results can be considered very promising because the data match the Strength Class D24 (EN 338), the same Class as full cross-section chestnut beams (at M.C.=12%).</p>

Bending Performance of Carbonized Bamboo Scrimber and Fracture Morphology Analysis after Different Ageing Treatments

2013 ◽  
Vol 744 ◽  
pp. 362-365 ◽  
Author(s):  
Xin Man Chang ◽  
Juan Wei ◽  
Ming Jie Guan
Keyword(s):  
Fracture Surface ◽  
Modulus Of Elasticity ◽  
Mechanical Test ◽  
Fracture Morphology ◽  
Modulus Of Rupture ◽  
Bending Performance ◽  
Sem Micrographs ◽  
Brittle Rupture ◽  
Bamboo Scrimber ◽  
Before And After

This paper described the influence of different ageing treatments on bending performance of carbonized bamboo scrimber according to three ageing standards (ASTM D1037, BS EN1087-1 and WCAMA). The modulus of elasticity (MOE) and modulus of rupture (MOR) were tested and the fracture morphology of the samples after mechanical test was also analyzed by SEM before and after ageing. The results showed that the average reduction rates of MOE and MOR were respectively 47.48% and 34.98%. In addition, SEM micrographs revealed that the fracture morphology of ASTM and BS EN presented smoother surfaces than WCAMA. The fracture surface of WCAMA was similar to Control but smoother in some parts. This was mainly due to the brittle rupture playing a dominating role in different degrees based on three ageing treatments. In conclusion, the brittleness of material after ageing was intensified leading to the decline of the bending performance.

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