13 - The potential of natural composite materials in structural design

Abstract

Fiber-reinforced composites are widely used in advanced structural applications, including aerospace. The reinforcement in these composites is usually synthetic or mineral fibers, such as carbon or glass fibers. Due to the advantages of natural fibers over their synthetic or mineral counterparts, they have been the center of attention for the past couple of decades. However, there are challenges to overcome before natural composites become more widespread in the advanced structural industry. In this study, two newly developed bio-based resins, derived from soybean oil, are combined with surface-treated flax fiber to produce novel bio-composites. Mechanical properties such as tensile and flexural strength, tensile and flexural moduli, interlaminar shear strength, and color gloss of the composite specimens before and after exposure to accelerated weathering (UV and moisture) have been studied. The results of this study reveal that bio-based composites using vinyl ester resin or 100% vegetable oil-based resins have the potential to be used in structural applications such as aerospace applications. In this study, the mechanical properties of manufactured composites showed improvement when using alkaline-treated flax fiber as reinforcement. In addition, after being exposed to accelerated weathering, the mechanical properties of composites using treated flax fiber showed lower reductions, with the exception of flexural strength. In general, it has been shown that the bio-based composites manufactured in this study meet, and most of the time exceed, the target properties set, based on commercially available pultruded fiberglass composites.