Progress in flame-retardant sustainable fiber/polymer composites

The worldwide demand for green and sustainable materials has given rise to production of composites from raw natural fibers and polymer matrices. In the past few decades, natural fibers have been widely used in polymer composites owing to their superior properties, which are comparable to or provide more advantages than those of synthetic fibers and traditional glass fibers in terms of mechanical properties, light weight, low cost, and minimal environmental and health hazards. However, the high combustibility of natural fiber-reinforced polymer composites (NFPCs) restricts their diverse applications, especially in engineering fields. To improve the flame retardancy of NFPCs, many researchers have made numerous efforts, such as incorporating traditional flame retardants or nanofillers and flame retardant-modified natural fibers into NFPCs and by applying non-flammable polymeric matrices in various fields. This chapter aims at summarizing the development of flame-retardant NFPCs based on open publications involving the types and properties of natural fibers and the recent progress in flame-retardant NFPCs based on different natural fibers and polymeric matrices. In addition, the flame-retardant mechanisms of the combination of natural fibers and flame retardants or nanoadditives in polymers have also been discussed. Finally, promising industrial applications of flame-retardant NFPCs will be discussed.