Wood Modification and Wood Preservation
Hamid reza Zarey; Reza Hajihassani; seyedeh masoomeh; Kamyar Salehi
Abstract
Background and Objectives: Wood has some limitations in properties and applications due to its natural nature, which need to be modified. Wood modification is usually done with different aims and methods. One of the wood modification methods is thermal treatments in order to improvement of dimensional ...
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Background and Objectives: Wood has some limitations in properties and applications due to its natural nature, which need to be modified. Wood modification is usually done with different aims and methods. One of the wood modification methods is thermal treatments in order to improvement of dimensional stability and biological resistance. But, it is surely affected on physical and mechanical properties of wood. Wood thermal modification in presence of oxygen causes the oxidation of its chemical structure which leads to decrement of physical and mechanical properties. Therefore, elimination of oxygen in thermal modification can reduce its destructive effects. In current study, the effect of thermo-oil process on the function of white rot fungus has been investigated. Moreover, the effect of this process on engineering properties of birch and pine wood species was evaluated.Methodology: In this study, two wood species of birch (Betula sp.) and pine (Pinus sp.) cut into the desired timbers. Heat treatment of the prepared timbers was carried out in a cylinder which equipped to the pressure and vacuum system. Also, industrial recycled oil was used for heat treatment of the timbers. The temperature and time treatment were considered 195 °C and 5 hours, respectively. At the end of the process, the used oil was drained into the oil storage tank and the timbers were removed from the cylinder after applying vacuum. In order to investigation of biological resistance as well as physical and mechanical properties (water absorption and swelling, density, mass loss, bending strength, compression strength parallel to the grain and impact strength) test specimens were prepared from the treated and control timbers based on the standard. The SPSS software was used for statistical analysis. The results were statistically analyzed based on a One-Way ANOVA method.Results: Results revealed that thermo-oil treatment can reduce the functionality of white rot fungus and also its efficiency on physical and mechanical properties of both wood species. Moreover, the results showed that this process improved the physical properties and reduced the mechanical properties, except compression strength parallel to the grain.Conclusion: Thermo-oil treatment at high temperature causes structural changes of wood and affects its physical and mechanical properties. Also, the structural changes caused by heat treatment can be an effective and inhibiting factor to functionality of white rot fungus on physical and mechanical properties of wood.
Wood Modification and Wood Preservation
Seyedeh Masoomeh Zamani; Reza Hajihassani; Kamyar Salehi
Abstract
AbstractThe purpose of this study was to evaluate effectiveness of brown rot fungus on ash (Fraxinus Sp.) and spruce (Picea Sp.) thermo-wood and also thermally modification on fungal functionality. In first step, prepared wood samples of both species were heat treated under 212 ºC for 3 hours. Afterwards, ...
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AbstractThe purpose of this study was to evaluate effectiveness of brown rot fungus on ash (Fraxinus Sp.) and spruce (Picea Sp.) thermo-wood and also thermally modification on fungal functionality. In first step, prepared wood samples of both species were heat treated under 212 ºC for 3 hours. Afterwards, heat-treated and untreated wood specimens were exposed to brown rot fungus for 16 weeks based on EN 313 and the functionality of fungal destructive agent and also its effect on physical and mechanical properties were finally analyzed. The obtained results showed that the brown rot fungus has been more efficiency on untreated specimens in compared with thermo-wood in both two wood species and caused more destruction and mass loss. Moreover, the results revealed that some physical and mechanical properties include density, compression parallel to grain and impact strength of exposed heated specimens to brown rot fungus were more than unexposed heated specimens to this fungus. Evaluation of laccase activity which produced by brown rot fungus showed more its effect on controls than heat treated specimens in both wood species. Based on the results, thermally modification can generally causes improvement of biological resistance, reduction of some physical and mechanical properties as well as more stability of applied properties of ash and Picea wood which exposed to the brown rot fungus.
Reza Hajihassani; seyedeh masoomeh; Saman Ghahri; Kamyar Salehi
Abstract
AbstractThe purpose of this study was to investigate the effect of heat treatment on bio-durability and some physical and mechanical properties of beech (Fagus Sp.) and pine (Pinus Sp.). Thermo-wood samples were prepared from beech and pine species based on thermo-D process. Heat-treated and untreated ...
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AbstractThe purpose of this study was to investigate the effect of heat treatment on bio-durability and some physical and mechanical properties of beech (Fagus Sp.) and pine (Pinus Sp.). Thermo-wood samples were prepared from beech and pine species based on thermo-D process. Heat-treated and untreated wood specimens were evaluated after exposing to brown rot fungus for 16 weeks. The laccase activity and its effect on mass loss and wood density were investigated. Results showed that deterrence value of heat treatment on mass loss caused by brown rot fungus have been 76.92% and 44.32% in beech and pine wood, respectively. So, laccase activity and its efficiency on mass loss of control specimens was more than heat treated wood. The results also showed that thermally modification at high temperatures reduced wood density. However, it had deterrent effect on decrease of density caused by brown rot fungus activity. Moreover, some mechanical properties including impact strength and compression parallel to grain of wood specimens were measured. The results generally showed that thermal modification improves the bio-durability of both wood species. The results also revealed reduction of mechanical properties due to heat treatment except compression parallel to grain.
Reza Hajihassani; Saman Ghahri; Kamyar Salehi; Fardad Golbabaei; seyedeh masoomeh
Abstract
Abstract In the current research, surface properties and failure modes of modified poplar wood (Populus deltoides) by hygrothermal treatment were evaluated. For this aim, the effect of variable factors included hygrothermal temperature (three levels: 130, 150 and 170°C) and holding time (two levels: ...
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Abstract In the current research, surface properties and failure modes of modified poplar wood (Populus deltoides) by hygrothermal treatment were evaluated. For this aim, the effect of variable factors included hygrothermal temperature (three levels: 130, 150 and 170°C) and holding time (two levels: 20 and 40 minutes) on poplar wood specimens properties (contact angle and surface roughness) prior to and after planning were investigated. The surface characteristics and failure modes were evaluated for both treated and untreated wood specimens. The results revealed that surface roughness of poplar wood was enhanced due to the hygrothermal treatment in both states of before and after planning. It was also found that the hygrothermal treatment decreased contact angle of distilled water. The bending strength of specimens was reduced by hygrothermal treatment. According to the results, failure modes of hygrothermally treated specimens were simple and compression types in bending strength test. Keywords: Surface roughness, contact angle, bending strength, failure mode
Composite wood products
Reza Hajihassani; Fardad Golbabaei; seyedeh masoomeh
Abstract
The aim of current research was to investigate effect of chemical treatment of poplar fibers on physical and mechanical properties of wood plastic composite. The samples were made from acetylated poplar fibers with different weight percent gains (WPGs of 0, 14.7 and 19.5%), two levels of fiber consumption ...
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The aim of current research was to investigate effect of chemical treatment of poplar fibers on physical and mechanical properties of wood plastic composite. The samples were made from acetylated poplar fibers with different weight percent gains (WPGs of 0, 14.7 and 19.5%), two levels of fiber consumption (30 and 40%) as well as two levels of MAPP (0 and 3%). The samples were physically and mechanically tested. Afterward, the results were analyzed based on a complete randomized design (CRD) under a factorial experiment. Results revealed that the acetylation causes reduction of water absorption and thickness swelling and also improvement of some mechanical properties. Moreover, the results showed that the utilization of MAPP increases physical and mechanical properties of wood plastic composite. The research results showed that increasing of fiber consumption from 30 to 40% enhances water absorption, thickness swelling, tensile strength, tensile modulus as well as bending modulus, and also causes reduction of bending strength and impact resistance.
Management and Economics wood
Reza Hajihassani; seyedeh masoomeh
Abstract
Abstract In this research, the effects of acetylation on the prevention of white-rot and brown-rot fungi deterioration in medium density fiberboard (MDF) were investigated. Sample boards were made from acetylated poplar fibers, which were treated at different times (0, 30, 90 and 270 minutes) to obtain ...
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Abstract In this research, the effects of acetylation on the prevention of white-rot and brown-rot fungi deterioration in medium density fiberboard (MDF) were investigated. Sample boards were made from acetylated poplar fibers, which were treated at different times (0, 30, 90 and 270 minutes) to obtain different weight percent gains (WPGs of 0, 4.85, 9.1, and 15.8 %). Totally twelve samples boards at three replication for every treatment were made.. The results were analyzed based on a complete randomized design (CRD) under a factorial experiment. Results revealed that the acetylation decreased the deterioration effect of white-rot and brown-rot fungi. As it was determined, the weight reduction of acetylated boards with the highest WPG (15.8 %) after 16 weeks were measured as 1.605 % and 16.93 % for white and brown-rot fungi, respectively. It was also determined that the weight loss of the control (untreated boards) samples was measured as 39.96 and 49.31% in the same period. The research results showed that the acetylation enhances biologic resistance in medium density fiberboard.
