Assessment of chemically treated wood for dimensional stability, strength property and termite resistance.

摘要

Experiments were conducted to assess the wood (Bombax ceiba) treated with thermosetting resins, viz., phenol formaldehyde (PF), melamine formaldehyde (MF) and urea formaldehyde (UF) and vinyl monomers (acrylonitrile, AN, and acrylamide, AA) for dimensional stabilization, strength and stiffness properties and termite (Odontotermes spp.) resistance. The permanency of the chemical retention of treated wood samples was also studied. Dimensional stability in terms of anti-shrinking efficiency was achieved 51.23-71.32% at 30.4-32.5 levels of weight percent grain (WPG). The maximum chemical loading that can cause maximum level of swelling of wood cell wall was achieved at 30% chemical concentration for a wide range of treatment times at 90-100 degrees C and 75 psi. Scanning electron micrographs showed the adhesion of the chemicals at 32.5, 32.1, 31.4, 30.4 and 31.3 levels of WPG for PF, MF, UF, AN and AA, respectively to cell wall resulted in bulking of the cell wall to give dimensionally stabilized wood. The infrared spectra of untreated and treated wood showed the reaction of chemicals with OH groups of the wood cell wall. After three cycles of repeated wetting and drying, the treatments resulted to bulking coefficient of 9.52-14.14% and moisture excluding efficiency of 30.20-42.25% of the wood at these levels of WPG. The treated wood showed increase in modulus of rupture by 7.33-21.01% and the stiffness, i.e., modulus of elasticity by 6.96-12.12% of the treated wood over the untreated one with no significant effects on the specific gravity. The resin treated samples also showed resistance to termite attack even after one year of exposure to termite colony.