All natural composite sandwich beams for structural applications

As part of developing an all natural composite roof for housing application, structural panels and unit beams were manufactured out of soybean oil based resin and natural fibers (flax, cellulose, pulp, recycled paper, chicken feathers) using vacuum assisted resin transfer molding (VARTM) technology. Physical and chemical investigations and mechanical testing of the beams yielded good results in line with desired structural performance. Room temperature curing of an acrylated epoxidized soybean oil (AESO) resin gave a flexural modulus of 1 GPa. Natural fiber reinforcement of 20-55 wt.% fiber increased the flexural modulus to 2-6 GPa. The same resin reinforced with woven E-glass gave a flexural modulus of 17 GPa. Using this type of composite in building construction introduces many advantages such as high strength and stiffness to weight, survivability in severe weather conditions, desired ductility, fatigue resistance, and design flexibility (three-dimensional forms, molded in place, easy to install and structure replacement). A bio-based (natural and biodegradable) matrix reinforced by natural fibers also provides an important environmental advantage, as renewable resources are used instead of petroleum-based materials. Five different structural beams were successfully manufactured and mechanically tested giving good results. Combinations of two different fibers were also introduced to give processing and strength advantages. (C) 2003 Published by Elsevier Ltd.