Original article A review on mechanical behavior of natural fiber reinforced polymer composites and its applications Hitesh Jariwala and Piyush Jain Abstract In the last decade, natural plant fibers (jute, sisal, coir, banana, hemp, kenaf, flax, etc.) are getting attention from many researchers and academicians to utilize it as an alternate reinforcement of synthetic fiber reinforced polymer compo- sites. These fibers are becoming a great replacement of conventional fibers (such as glass, carbon, and aramid) due to their light weight, low cost, carbon neutrality, fairly good mechanical properties, high specific strength, and biodegrad- ability characteristics. Some chemical treatments are required to enhance the fiber matrix interfacial strength and to minimize the moisture absorption by these fibers which would ultimately improve physico-mechanical properties of these fiber reinforced composites. This paper is a review on mechanical properties of the natural plant fiber reinforced polymer composites and various factors affecting the mechanical performance of it. The tribological behavior of natural fiber reinforced polymer composites and scanning electron microscope analysis are also discussed. Some mathematical models are mentioned which are useful to predict mechanical behavior of the composites. It is found that Halpin–Tsai equation is the most effective equation amongst others in predicting Young’s modulus for short-fiber reinforced composites with minimum error. The applications of natural plant fiber reinforced polymer composites in various engineering fields are discussed. Keywords Natural fiber, composites, mathematical models, mechanical properties, tribological behavior, scanning electron microscope study, applications Introduction The natural fiber reinforced composites have become realistic alternatives to conventional glass fiber compo- sites in many engineering applications in past decade. The use of natural fiber, as reinforcement, with poly- mers is gaining attention of many researchers in the domain of composite materials. The synthetic fiber composites like aramid, carbon, and glass fiber rein- forced plastics are widely used in automobile, aero- space, construction, leisure, and sporting industries since long. Glass fibers are widely used due to their low cost and fairly good mechanical properties com- pared to aramid and carbon. 1 However, these fibers have some serious drawbacks as listed in Table 1. Natural fiber composites, thermosets, and thermoplas- tics have attracted greater attention due to their advan- tages like low density, low cost, renewability, recyclability, CO 2 neutral, etc. 2 Natural fibers are con- sidered one of the environmentally friendly materials having good properties compared to synthetic fibers. Natural fiber polymer composite industries are growing around the world. As indicated by evaluations during 2011–2016, the natural fiber polymer industry was estimated to grow 10% worldwide. 3 Natural fiber rein- forced composites with a high specific stiffness and strength can be produced by adding the tough and light weight natural fibers into polymer (thermoplastics and thermosets). The most common and commercially natural fibers in the world and world production are shown in Table 2. Natural fiber composites are used in place of glass mostly in non-structural applications. So far a good number of automotive components are Mechanical Engineering Department, Gujarat Technological University, Ahmedabad, Gujarat, India Corresponding author: Hitesh Jariwala, Mechanical Engineering Department, Gujarat Technological University, Ahmedabad 382424, Gujarat, India. Email: hsj.jhdp@gmail.com Journal of Reinforced Plastics and Composites 0(0) 1–13 ! The Author(s) 2019 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0731684419828524 journals.sagepub.com/home/jrp