GLUABILITY OF COPOLYMER RESINS MADE OF TREE FOLIAGE EXTRACTS, PHENOL, AND FORMALDEHYDE FOR SOUTHERN PINE PLYWOOD

Foliages of southern pine (Pinus taeda), Douglas-fir (Pseudotsuga menziesii), and western hemlock (Tsuga heterophylla) were extracted with a 10% sodium hydroxide solution at 95-degrees-C and 40-degrees-C. Copolymer resins of phenol, formaldehyde, and the foliage extracts were synthesized having 40% and 60% by weight of chemical phenol replaced with the foliage extracts. The copolymer resins were evaluated for gluability with southern pine plywood. Hot press time requirements of the copolymer resins were also investigated. A commercial P-F resin was used as the control in all investigations. The experimental copolymer resins of 40% (by weight) Phenol replacement exhibited good bond quality even at a hot press time of 2 minutes for three-ply, 0.95 cm (3/8 inch) thick panels, one panel per opening at 149-degrees-C (300-degrees-F) platen temperature. Though the bond quality of the commercial P-F resins was unsatisfactory at the shortest press time, it provided satisfactory bond quality at the longer hot press times. The copolymer resin containing extracts of southern pine foliage retained its fast curing and assembly time tolerance properties even at a higher phenol replacement of 60% (by weight). However, copolymer resins of Douglas-fir and western hemlock extracts did not provide satisfactory bond quality at 60% (by weight) phenol replacement.