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Effect of resin type on properties of steam-press-cured flakeboards

Informally Refereed

Abstract

Six potentially important wood adhesives for gluing southern pine and white oak flakeboards were evaluated for their performances in steam-injection pressing and conventional platen pressing. Of the six resins tested, polyisocyanate resin performed well in both steam injection and conventional platen pressings. Phenol-fonnaldehyde (PF) and melamine urea-fonnaldehyde (MUF) resins performed poorly in steam-injection pressing. However, adding a small amount of polyisocyanate improved performance considerably. Bending strengths were consistently higher with conventional platen pressing than with steam-injection pressing. The lower density face in steam-injection pressing would result in lower bending properties. In PF and MUF resin systems, steam-injection pressing resulted in low bond strength and high dimensional stability, whereas conventional platen pressing resulted in high bond strength and low dimensional stability. The pairing of low strength with high stability suggested that bonding strength could not be the cause of improvement in dimensional stability. Most probably, steam pressing reduced internal stresses and stabilized the flakes, which in turn resulted in an improvement in dimensional stability. The improvement in dimensional stability may also be related to less strength loss of the board in steam-injection pressing when exposed to high relative humidity treatment.

Citation

Hse, Chung-Yun; Geimer, Robert L.; Hsu, W. Ernest; Tang, R.C. 1995. Effect of resin type on properties of steam-press-cured flakeboards. Forest Products Journal, Vol. 45(1): 57-62
https://www.fs.usda.gov/research/treesearch/24263