The purpose of this study was to evaluate two groups of composite panels made from two types of underutilized natural fiber sources, kenaf bast fiber and office wastepaper, for their suitability in composite panels. All panels were made with 5% thermosetting phenol-formaldehyde (PF) resin and 1.5% wax. Also, an additional 10% polypropylene (PP) thermoplastic resin was used in half the panels. The PP was added to determine the effect it had on the mechanical and physical properties of the panels. The resin and wax were applied with a pneumatic spray gun while tumbling the fiber in a rotary blender. All fibers were formed into nonwoven air-laid mats and compression molded into 356- by 356-mm (14- by 14-in.) composite panels, cut into test specimens, and tested for mechanical and physical properties. All mechanical property values were below the minimum standard established by the American Hardboard Association for medium-density fiberboard and particleboard (AHA 1995). However, composites with PP had more short term moisture resistance than did composites without PP. The poor mechanical test results were probably due to the PF resin being absorbed into the fiber rather than remaining on the fiber surface, insufficient cure of PF, and interference of the PP when used with the PF resin.
Muehl, James H.; Krzysik, Andrzej M.; Chow, Poo. 2004. Composite panels made with biofiber or office wastepaper bonded with thermoplastic and/or thermosetting resin. Res. Note FPL-RN-0294. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 6 pages