US EPA

5945690 

Journal Article 

PHENOLIC ADHESIVE BONDS TO ASPEN VENEERS TREATED WITH AMINO-RESIN FIRE RETARDANTS 

Vick, CB 

1994 

1 

Forest Products Journal
ISSN: 0015-7473
EISSN: 2376-9637 

44 

1 

33-40 

WOS:A1994MR45900006 

Structural failures of fire-retardant-treated wood may be caused by hydrolysis of the wood by acidic fire retardants. Amino-resin fire retardants are acidic, but they are believed to minimize the risk of failure from acid hydrolysis. The purpose of this study was to determine if a phenolic-based adhesive bonding system could produce strong and highly durable bonds to aspen veneers treated with urea/dicyandiamide/ phosphoric acid/formaldehyde (UDPF) fire retardant, which is an amino-resin fire retardant, and with UDPF fire retardant combined with didecyldi methylammonium chloride (DDAC) preservative. The aspen veneers were pressure treated with appropriate molar ratios of UDPF at total retentions of 6.0 and 9.0 lb./ft.(3) [96 and 144 kg/m(3)]. To improve adhesion, water solutions of Na2CO3 and NaOH were applied as surface treatments before bonding. Integrity of the bonds was determined from wet wood failure and shear strength. Two of the three phenol-formaldehyde (PF) adhesives tested developed bonds of high wet wood failure and shear strength on aspen veneers treated with an amino-resin fire retardant - but only when a surface treatment was used. When 0.6 lb./ft.(3) [9.6 kg/m(3)] of DDAC was combined with UDPF at the same retention levels, adhesion of the PF adhesives was poor and the two alkaline surface treatments were ineffective at improving adhesion. Concentration of nonpolar alkyl groups of DDAC at the surface of the wood interfered with penetration of polar PF adhesives. 

Populus tremuloides; adhesives; phenols; flame retardant finishes; bond strength; veneers