Composite wood products
Morteza Ghanbari; vahid vaziri; Farshid Faraji; loya jamalirad
Abstract
Background and objective: Wood, as a natural and renewable material, in addition to its numerous advantages, possess some disadvantages, including its deterioration when exposed to outdoor conditions and its dimensional instability due to fluctuations in relative humidity in the surrounding environment. ...
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Background and objective: Wood, as a natural and renewable material, in addition to its numerous advantages, possess some disadvantages, including its deterioration when exposed to outdoor conditions and its dimensional instability due to fluctuations in relative humidity in the surrounding environment. Heat treatment can enhance the dimensional stability of panel products, such as particleboard, fiberboard, and OSB. Because heat treatment causes chemical changes in wood, including decrease in hemicellulose and the number of hydroxyl groups. The main objective of this research was to assess the effect of steam pretreatment of orchid tree pruning - wood particles on the physical and mechanical properties of particleboard.
Materials and methods: Industrial wood particles from Sanate Choube Shomal Company were used. The ratio of wood chips to orchid tree pruning was used at the level of 70:30. Heat pretreatment was conducted on the wood particles at the temperature of 180 °C with three different retention times (15, 30, and 45 minutes). Urea formaldehyde resin was applied at 10 percent level based on the dry weight of the raw material as well as ammonium chloride was used as a catalyst at a 2 percent level of the dry weight of the adhesive. After the heat treatment and the mixing processes, the raw materials were formed into a mat and then pressed at temperature of 160 °C for 5 minutes. The physical and mechanical properties of the boards were evaluated according to European standards test methods (EN326-1). The analysis of the physical and mechanical properties of the panels were performed using variance analysis at a 95% probability level.
Results: The results showed that the boards made from treated particles with a 45-minute treatment duration exhibited the highest bending strength, modulus of elasticity, and internal bonding. Since heat treatment softens and ramified the lignin and increased the crystallization of cellulose, which improves the strength of the board. Thickness swelling and water absorption of the boards were significantly improved with increased treatment duration. The main reason for dimensional stability can be attributed reduction of hemicellulose content and hydroxyl groups within the wood component.
Conclusion: Based on the findings of this research, heat treatment significantly improved the dimensional stability of the boards. Bending strength, modulus of elasticity, and internal bonding in the treated samples displayed the highest measured values. In comparison to the properties of the treated boards at 30-minute and 45-minute duration demonstrated the potential to produce particleboards with desirable attributes suitable for interior application (Type P2) for application in dry conditions.
Composite wood products
Mohamad Noorirad; Hedayatolah Aminian; Loya Jamalirad; Vahid Vaziri
Abstract
Background and objectives: Many studies have been conducted on the use of cellulosic resources to provide portion of raw materials for wood and paper industries. Waste branches for some species such as palm and Prosopis cineraria in southern parts of country can be a solution for deficiency of raw material ...
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Background and objectives: Many studies have been conducted on the use of cellulosic resources to provide portion of raw materials for wood and paper industries. Waste branches for some species such as palm and Prosopis cineraria in southern parts of country can be a solution for deficiency of raw material in wood and paper industries. This study investigated the possibility of using a combination of Prosopis cineraria and industrial wood particles to produce particleboard with acceptable physical and mechanical properties.Methodology: The variables in this study were the ratio of Prosopis cineraria to industrial wood particles at four levels (0:100, 15:85, 30:70, 45:55) and urea formaldehyde resin at two levels (10 and 12 percent). Industrial wood particles from Sanate Choube Shomal Company and Prosopis cineraria particles were obtained from the province of Sistan and Baluchistan. Ammonium chloride as a hardener was used at 2 percent of the dry weight of the adhesive. After mixing raw material, the mat was placed under hot pressing at a temperature of 170 ˚C for 6 minutes. After the manufacture of the single-layer particleboard, the physical and mechanical properties of the boards were analyzed by a factorial test in a completely randomized design with a confidence level of 5%. Results: The results showed that the physical and mechanical properties of the panels decreased as the percentage of mixture Prosopis cineraria particles increased. So that, panels containing 45% Prosopis cineraria particles and 10% urea-formaldehyde resin had the lowest mechanical properties, while panels containing 12% urea-formaldehyde resin without Prosopis cineraria s particles had the best mechanical properties. Panels containing 45% Prosopis cineraria particles and 12% urea-formaldehyde resin had the lowest water absorption and thickness swelling, while panels containing 10% urea-formaldehyde resin without Prosopis cineraria particles had the highest.Conclusion: According to the results of this study, there was usability of boards with 15% Prosopis cineraria particles and 10% resin for Type P1 boards and the boards with 15% Prosopis cineraria particles and 12% resin for Type P2 boards.
