The effect of chitosan utilization on dimension stability of particleboard

the dimension stability of wood panels is one of the most challenges in these related industries. The humidity absorption not only changes the appearance and physical properties, but also it affects the mechanical structure and reduces the strengths. There are different methods for solving this problem such as chemical modification, monomer saturation, and thermal treatment. The disadvantages of each method are mechanical properties reduction and environmental problems. Chitosan is used in this study which it is the most abundant biopolymer after cellulose as a biodegradable and less reduction in mechanical strength. Chitosan is derived by chitin. Chitin is an amino-polysaccharide which it is polymerized by N-acetyl-D-glucosamine associated with B(1-4) linkages. Chitosan coated the particles and preserved them to humidity absorption. On the other hand, the thickness swelling and water absorption are decreased because the hydroxyl groups of wood are replaced by the acetamide groups of chitosan.

in this study, the wood mixture of forest species with variable factors (the amount of chitosan 2%, 4% ; thermal treatment temperature 120oc, 140oc, 160oc; and two types of adhesives urea formaldehyde and urea-melamine formaldehyde in ratio of 50/:50) is used which followed by the fixed factors (pressure, temperature and press time , 25 bar, 165oc, and 6 min, respectively). The amount of 42 particleboard samples with 10 mm thickness and 20*30 cm3 has been made. According to EN-317 standards, the samples with 10*50*50 mm3 dimensions are examined by 2 and 24 hours for water absorption and thickness swelling tests.

the particleboards are made by urea-melamine formaldehyde indicated less water absorption and thickness swelling rather than urea-formaldehyde. The water absorption and thickness swelling are decreased by using chitosan. By increasing the amount of chitosan utilization, the water absorption and thickness swelling are decreased. Increasing of thermal treatment temperature reduces the water absorption and thickness swelling.

With regards to different treatments in this study, the results showed that the optimal treatment conditions for decreasing of water absorption and thickness swelling are urea melamine formaldehyde, chitosan 4%, and thermal temperature 160oc. Keywords: particleboard, chitosan, dimension stability, Water absorption, Thickness swelling

the particleboards are made by urea-melamine formaldehyde indicated less water absorption and thickness swelling rather than urea-formaldehyde. The water absorption and thickness swelling are decreased by using chitosan. By increasing the amount of chitosan utilization, the water absorption and thickness swelling are decreased. Increasing of thermal treatment temperature reduces the water absorption and thickness swelling.

With regards to different treatments in this study, the results showed that the optimal treatment conditions for decreasing of water absorption and thickness swelling are urea melamine formaldehyde, chitosan 4%, and thermal temperature 160oc.