<Note>Properties Enhancement of LVLs Modified with Some Cross-Linking Agents

Abstract

Chemically-modified laminated veneer lumbers (LVLs) were produced and their physical properties and biological resistance were evaluated. For the chemical modification, the vapor-phase formalization and the pad-dry-cure treatment of veneers with some cross-linking agents were employed prior to lamination of the treated veneers. The vapor-phase formalization was conducted for 5, 10 and 24 hours using tetraoxane as a source of formaldehyde, and the pad-dry-cure treatments with glutaraldehyde and dimethylol dihydroxy ethylene urea (DMDHEU) were made after impregnation of their 2.5, 5 and 10% aqueous solutions. Sulfur dioxide was used as a catalyst in both treatments. Laboratory tests with a brown-rot and a white-rot fungus revealed that decay was almost completely suppressed at the high levels of treatment, and fairly eliminated at the low levels of treatment. The treatment could reduce the weight loss of specimens caused by termite attack, but the effectiveness in resisting it was not as sufficient as was decay resistance. All treated LVLs were very stable to water soaking even in the 2-hour boiling on thickness swelling as well as linear expansion along tangential direction.