Document Type : Research Paper
Authors
1 M.Sc. Graduated of Wood Composite Products, Gonbad Kavous University, Gonbad Kavous, Iran
2 Assistant professor
3 Associate Prof., Wood and Paper Science and Technology, Gonbad Kavous University, Gonbad Kavous, Iran
Abstract
Background and objective: While wood serves as an excellent renewable building resources, it does have 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 during the heat treatment process, numerous chemical transformations take place, including the esterification of hydroxyl groups and the reduction of hemicellulose along with the number of accessible OH groups within the wood. The main objective of this research was to assess the effect of steam pretreatment of garden wood 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 garden wood pruning was used at level of 70:30. Heat pretreatment was conducted on the wood particles at a temperature of 180 °C with three different retention times (15, 30, and 45 minutes). Urea formaldehyde resin was applied at a 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 at temperature of 160 °C for 5 minutes under a hot press. The physical and mechanical properties were evaluated according to European standards set of EN. The analysis of the Physical and mechanical properties of the panels was 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 ramification of lignin and crystallization of cellulose ratio increases, 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 finding 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 boards produced by EN standards, the treated boards at 30 minute and 45 minute duration demonstrated the potential to produce particleboards with desirable attributes suitable for interior fitments board (Type P2) for application in dry conditions.Based on the finding 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 boards produced by EN standards, the treated boards at 30 minute and 45 minute duration demonstrated the potential to produce particleboards with desirable attributes suitable for interior fitments board (Type P2) for application in dry conditions.
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