Research Institute of Forests and Rangelands Iranian Journal of Wood and Paper Science Research 1735-0913 40 2 2025 05 22 The effect of heat treatment on physical and mechanical properties of particleboard produced from orchard trees pruning - industrial wood particles The effect of heat treatment on physical and mechanical properties of particleboard produced from orchard trees pruning - industrial wood particles 124 137 133082 10.22092/ijwpr.2025.367890.1789 FA Morteza Ghanbari M.Sc. Graduated of Wood Composite Products, Gonbad Kavous University, Gonbad Kavous, Iran Vahid Vaziri Assistant Prof., Wood and Paper Science and Technology, Gonbad Kavous University, Gonbad Kavous, Iran Farshid Faraji Assistant Prof., Wood and Paper Science and Technology, Gonbad Kavous University, Gonbad Kavous, Iran Loya Jamalirad Associate Prof., Wood and Paper Science and Technology, Gonbad Kavous University, Gonbad Kavous, Iran Journal Article 2024 12 08 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. 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.

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