Chapter 4 - Natural fibers: Their composites and flammability characterizations

Abstract

The concept of green composites offers challenges to the designers in many aspects, which warrants the identification of more environment-friendly resources. In this regard, replacing synthetic fibers with natural ones in composite materials has to play a major role in manufacturing engineering. The advantages, such as low cost, low density, high toughness, relatively high specific strength properties, low abrasiveness, low energy consumption in fabrication, and CO2 neutrality of some natural fibers, provide the researchers incentives to use these materials in new developments. Most recent research efforts have removed many fiber–matrix compatibility problems; however, poor thermal stability is a major drawback in using these materials, especially in transportation and aerospace applications. Generally, natural fibers are considered as heat sources in composites. If the fiber cellulose content is high, it tends to increase the flammability due to high levels of levoglucosan, but the amount of lignin content in the fibers leads to char formation after initial ignition and provides a thermal barrier. This phenomenon can be used to control the fire growth, by selecting good combination of materials and obtaining effective homogeneous composites under suitable processing conditions.