Vikram Yadama1,Avishek Chanda1,Muhammad Bakri1,Lloyd Smith1
Washington State University1
Vikram Yadama1,Avishek Chanda1,Muhammad Bakri1,Lloyd Smith1
Washington State University1
Forming bio-based materials into complex three dimensional shapes can be enhanced using a “prepreg” like material. Adapting bio-based materials into material forms that have successfully been used with synthetic composites allows downstream manufacturing of compression molded panels for a variety of higher value applications. This presentation will discuss the development of a natural fiber prepreg for a variety of applications including automotive interior and exterior panels. Wood strands produced from small diameter trees were stitched to make a preform, which was then injected with a liquid thermoplastic resin, Elium<sup>®</sup> (produced by Arkema), using a vacuum assisted resin transfer molding (VARTM) technique. The outcome was a thin and flexible thermoplastic wood prepreg with an average thickness of 0.017-in.<br/>Lumens of wood strands were completely filled with the thermoplastic resin resulting in 38% and 124% higher Young’s modulus and strength, respectively, of the saturated wood strands compared to wood strands prior to being infused with resin. A temperature and pressure for the thermoforming process were determined, and these thin and flexible thermoplastic wood-strand prepregs were then laminated by compression molding into panels that are flat or profiled with three-dimensional cross-sections. Compared to wood-strand panels produced using compression resin transfer molding (CRTM) and epoxy resin, Young’s modulus and strength of a flat laminate, made of 12 layers of wood prepreg, were 73% and 20% higher, respectively. Prepreg laminates are resistant to moisture uptake and are dimensionally stable as reflected in the water absorption and thickness swelling results. The ability to recycle these thermoplastic composites reinforced with renewable fibers at the end of their service life fits within the circular economy model. These new opportunities and applications for wood strands from small diameter timber would also contribute to sustainable forest management.