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Properties of wood/agricultural fiberboard bonded with soybean-based adhesives

1998; Forest Products Society; Volume: 48; Issue: 2 Linguagem: Inglês

2376-9637

Monlin Kuo, Daniel Adams, Deland J. Myers, Daniel J. Curry, Howard Heemstra, John L. Smith, Yilin Bian,

Forest Biomass Utilization and Management

There is a growing interest in the wood industry to develop wood adhesives from renewable substances and to use underutilized agricultural residues as supplements for wood composite panels. This study was conducted to determine comparative properties of hardboards and medium-density fiberboards (MDF) made from fiber furnishes containing different amounts of cornstalk, switchgrass, and wood fibers bonded with synthetic resins and soy protein. Hardboards and MDF were made at wood/agricultural fiber compositions of 100/0, 75/25, 50/50, 25/75, and 0/100 in weight percentages. Wet-formed hardboards (S1S) bonded with 2 percent soy protein were compared with those bonded with 2 percent phenol-formaldehyde resin (PF). Dry-formed hardboards (S2S) and MDF bonded with 4 percent PF plus 4 percent soy protein were compared with those bonded with 8 percent urea-formaldehyde (UF) resin. The results show that board properties decreased with increasing amounts of cornstalk and switchgrass fibers in the board. Board properties affected in descending order were thickness swell, internal bond strength (IB), tensile strength, bending strength (MOR), and bending stiffness (MOE). Boards containing 50 percent agricultural fibers had optimum mechanical properties when compared with those of 100 percent wood fiberboards. S1S boards bonded with 2 percent soy protein were inferior to those bonded with 2 percent PF. S2S boards bonded with 4 percent soy protein plus 4 percent PF had mechanical properties comparable to those of boards bonded with 8 percent UF and better dimensional stability. MDF bonded with 4 percent soy protein plus 4 percent PF, however, had lower mechanical properties than boards bonded with 8 percent UF. Results indicate that 1) wood fiber was superior to cornstalk and switchgrass fibers; 2) cornstalk fiber was better than switchgrass fiber in the production of fiberboard; and 3) the soy protein adhesive bond was not as strong and durable as synthetic resin adhesive bonds.