Coconut Husk Fibers

Abstract

About 62 million tons of coconuts are grown in about 92 countries across the world. Coconut trees or palms and the husks of the coconut fruit have extensively been used as sources for fibers. Fibers obtained from the husks (Fig. 9.1) of coconuts are generally termed “coir fibers” and are used for a variety of applications. Each coconut or copra yields about 80–90 g of husk fibers in Asia, whereas coconuts grown in the Caribbean contain thick husks and could yield up to 150 g of fiber. Each husk is composed of about 70 % pith and 30 % fiber and consists of 60 % long (150–350 mm), 30 % medium, and 10 % short fibers (<50 mm). About 5–6 million tons per year of brown coir and 125,000 tons of white fiber, mostly in India, are produced every year [13Van]. Fibers are obtained from the husks using conventional retting and chemical and biological means. In a conventional process, the husks are retted in brackish water for 3–6 months or in saltwater for 10–12 months to soften the fibers. Later, the fibers are separated by decorticating and beating and hackled and washed. This traditional processing yields the finest and whitest fibers. Alternative to traditional retting, mechanical processes to defibrillate or decorticate the husk have been developed. These machines and processes can process husks that have been treated for 5 days in water, but the quality of the fibers is heavily dependent on the processing conditions and severity of treatments. Recently, enzymatic processes have also been developed that are cleaner and milder and produce fibers with better quality.