Flake storage effects on properties of laboratory-made flakeboards
Research Note Forest Products Laboratory, USDA Forest Service
Aspen (Populus gradidentata) and loblolly pine (Pinus taeda) flakes were prepared with tangential-grain and radial- grain faces on a laboratory disk flaker. These were gently dried in a steam-heated rotary drum dryer. Approximately 1 week after drying, surface wettability was measured on a large sample of flakes using an aqueous dye solution. Three replicate boards of each combination of flake species and face grain were then fabricated. Each of the three replicate boards was made with a different adhesive resin. The three adhesives were urea-formaldehyde, phenolic, and neat isocyanate. The procedure (wettability measurements and board fabrication) was repeated at 1 month, 6 months, and 12 months after flake preparation. Surface wettabilities were reduced as the flake surfaces aged. Tension strengths of boards perpendicular to their faces (internal bond strengths) were also reduced as flake surfaces aged, and reductions in internal bond strengths and surface wettabilities appear to be related. Bending proper- ties were, in general, not influenced by flake age. The ob- served reductions in internal bond strengths suggest that laboratory storage of flakes for much longer than 6 months is not a good practice. However, no conclusive statements can be drawn from this work concerning the influence of flake aging on board properties.
Carll, C., "Flake storage effects on properties of laboratory-made flakeboards" (1998). Aspen Bibliography. Paper 1302.