Sisal plant, fiber extraction

A pilot plant ia India has been estabUshed to extract fiber, pulp, and juice from the leaves of sisal plants. The fiber is sold direcdy or used to manufacture rope, the cmshed pulp is used ia paper processiag, and the juice is an excellent source of hecogenin. During a three- to five-day fermentation of the juice, partial enzymatic hydrolysis causes hecogenin to precipitate as the hemisaponin ia the form of a fine sludge. This sediment is hydrolyzed with aqueous hydrochloric acid, neutralized, and filtered. This filter cake is washed with water and extracted with alcohol. The yield of hecogenin varies between 0.05 and 0.1% by the weight of the leaf (126). 

Such an approach to fiber classification appears to be systematic and objective. Unfortunately, plants do not always follow the pattern of roots, trunk, leaves, seed, or fruit. There are anomalies. For example, the banana-like plants, yielding abaca, do not have the woody trunk conventionally associated with other plants. Instead, its stem consists of layers of thick, crescentshaped (in cross section) sheaths wrapped around each other they reduce to spindly growths that unfurl from the stem and become the thick central stems of fronds (see Section 8.2.1). Botanically, the sheath-frond system is called a leaf consequently, the fiber extracted from the sheath is classified as leaf fiber. On the other hand, sisal or henequen fibers come from the swordlike leaves of their respective plants. Bagasse (from sugarcane) fiber, used for paper or fiberboard, comes from the stem, which is neither a leaf nor a woody trunk. Thus, the classification of fibers as seed, bast, leaf, or miscellaneous fibers is somewhat arbitrary. 

The dimensions of cells (length, diameter) are highly variable, dependent on species, maturity, location (position) within the plant, and extraction procedures. Meaningful comparisons can be made only in terms of orders of magnitude. Harris [58] collected the most comprehensive set of data from different sources. Table 8.2 is a composite of these, and other data, for fibers of interest and some for purposes of comparison. From these data, it is quite clear that, on average, the unit cells of ramie, flax, and hemp are longer and coarser than the cotton fiber jute, abaca, and hemp yield the longest fibers, and abaca, henequen, and sisal yield the coarsest fibers. 

The sisal plant is shown in Fig. 22.1. Sisal fiber is a very strong and important leaf fiber [3]. It is extracted from the leaves of the sisal plant (Agave sisaland) and is very hard [5]. 

In this method leaves of sisal plant are boiled, subsequently beating is done then after washing and sun drying we may get the usable clean fiber. This method is not suitable for large-scale extraction [15]. 

Natural fibers vary widely in chemical composition, stmcture, and dimension and are obtained from different parts of the plants. Natural fibers, such as jute, ramie, flax, kenaf, and hemp are obtained from the stem abaca, sisal, banana and pineapple from the leaf cotton, coir, and kapok from the seed grass, and reed fibers (com, rice, and wheat) [4]. Climatic conditions, age, and fiber extraction... 

Ramie is a bast fiber obtained from the perennial herbaceous plant, Boehmeria nivea. It is mainly grown in China, India, Japan, Korea, and Philippines. Ramie plants are one of the fast-growing plants and can be harvested within an interval of a few months. Three crops of this plant can be harvested every year. Sisal is a hard fiber extracted from the leaves of the sisal plant Agave sisalana). The length of sisal fiber is between 1.0 and 1.5 m and the diameter is about 100-300 tm. 

Preparation of Other Antigenic Materials. Cotton plant tissues (stem, leaf, burr), cotton gin trash, baled cotton, clean cotton lint, both hand picked in the field and from plants grown in the greenhouse, cottonseed proteins, cottonseed hulls, house dust, and flax, soft hemp, sisal, and jute fibers, were extracted with deionized water. The purification process was, however, stopped to correspond to f-3 (see Figure 1). 

Sisal varies in quality. The large variations in its chemical compositions are because of its different sources, age, extraction methods, etc. [23]. Eor example, Wilson [13] indicated that sisal fiber contains 78% cellulose, 8% lignin, 10% hemicelluloses, 2% waxes, and about 1% ash by weight, whereas Rowell et al. [24] found that sisal contains 43-56% cellulose, 7-9% lignin, 21-24% pentosan, and 0.6-1.1% ash. The work carried out by Chand and Hashmi [25] showed that the cellulose and lignin contents of sisal vary from 49.62 to 60.95% and 3.75 to 4.40%, respectively, depending on the age of the plant. 

Mauritius Hemp. Mauritius hemp, also called piteira, is obtained from Furcraea gigantea, also a member of the Agavaceae. The plant is mostly grown on the island of Mauritius, but is also harvested in Brazil and other tropical coimtries. The leaves are longer and heavier than those of the agaves. The fiber is extracted by mechanical decortication. It is whiter, longer, and weaker than sisal fiber. Because of its color it is used in blends. 

Plants are very attractive and potential sources of cellulose primarily because they are abundant and relatively cheap to harvest. Cellulose can be extracted from lignocellulosic fibers, which are available aU over the world. A wide variety of plant materials like cotton, ramie, sisal, flax, wheat straw, tubers, sugar beet, soya bean, etc., are known for cellulose microfibril production. Wood is another main important source of extracting cellulose fibrils, where cellulose microfibrils were reinforced by intracellular amorphous materials made of hemicelluloses, lignin, resin, etc. Extraction of pure cellulose microfibrils from these lignocelluloseic materials involves chemical treatments such as alkali extraction and bleaching. 

Natural fibers are the most common biorenewable polymers available in abundance all around the globe. Some of the commonly occurring natural fibers all around the globe include flax, hemp, baggase, jute, pine needles, pineapple leaf, sisal, grewia optiva, hibiscus sabdariffa (Santos et al., 2013], Figure 1.2 shows the extraction of pineapple leaf fiber from its plant. 

Biofibers are classified according to the part of the plant they are extracted from. Some fibers, like cotton, are part of the seeds of plants. Some fibers, like hemp and flax, are contained within the tissues of the stems of plants and referred to as bast fibers. Some fibers, like sisal and banana, are part of the leaves of plants. Some fibers, like coconut, are part of the fruit of plants. Biofibers most commonly used as reinforcements in composites are shown in Table 10.2. 

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