22. Sisal Fiber Based Polymer Composites and Their Applications

The natural resources of the World are depleting very fast due to the high rate of exploitation and low rate of restoration, leading to an increase in global warming and pollution hazards. In recent years, there has been increasing interest in the substitution of synthetic fibers in reinforced plastic composites by natural plant fibers such as jute, coir, flax, hemp, and sisal. Sisal is one of the natural fibers widely available in most parts of the world; it requires minimum financial input and maintenance for cultivation and is often grown in wastelands, which helps in soil conservation. Advantages of sisal fiber are: low density and high specific strength, biodegradable and renewable resource, and it provides thermal and acoustic insulation. Sisal fiber is better than other natural fibers such as jute in many ways, including its higher strength, bright shiny color, large staple length, poor crimp property, variation in properties and quality due to the growing conditions, limited maximum processing temperatures. In recent years, there has been an increasing interest in finding innovative applications for sisal fiber-reinforced composites other than their traditional use in making ropes, mats, carpets, handicrafts, and other fancy articles. Composites made of sisal fibers are green materials and do not consume much energy for their production.

The characteristics of composites depend on different parameters such as extraction of fiber, surface modification and the synthesis of composites. During synthesis, fiber length, orientation, concentration, dispersion, aspect ratios, selection of matrix, and chemistry of matrix have to be considered to achieve the required strength. Inorganic fibers have several disadvantages, including their nonbiodegradability, the abrasion in processing equipments, high cost and density, and the health problems caused to workers during processing and handling. Commonly used composites, these days are, glass, aramid, carbon, and asbestos fibers filled in thermoplastic, thermoset, or cement composites. Yet natural fiber composites with equivalent characteristics to synthetic fibre composites are not available. Most of the plant fibers are hydrophilic in nature and water absorption may be very high. This may be controlled by different methods of interfacial surface modification. Because of the low density and high specific strength and modulus. Sisal fiber is a potential resource material for various engineering applications in the electrical industry, automobiles, railways, building materials, geotextiles, defense and in the packaging industry. Present chapter discuss about the research work on sisal cultivation, fiber extraction, processing, sisal fiber characteristics, and the use of sisal fiber in thermoplastic and thermoset polymer composites for various engineering applications.