Classification of Natural Fibers

Natural fibers are classified based on their origins, whether they are plant, animal or mineral fibers. All plant fibers are composed of cellulose while animal fibers consist of proteins (hair, silk, and wool). Plant fibers include bast (or stem or soft scleren-chyma) fibers, leaf or hard fibers, seed, fruit, wood, cereal straw, and other grass fibers [1]. Over the last few years, a number of researchers have been involved in investigating the exploitation of natural fibers as load bearing constituents in composite materials. The use of such materials in composites has increased due to their relative cheapness, their ability to be recycled, and because they can compete well in terms of strength per weight of material [2]. Provided below is the classification of natural fibers based on origin ... 

Application of Natural Fiber as Reinforcement 529 23.1.3 Classification of Natural Fibers... 

The first step in caring for museum fabrics is to understand them as materials physical and chemical properties of fibers, yams, and fabrics the fabrication method and technique the design layout and color trend factors related to use and the pre- and postacquisition state. Subsequent studies should try to date the objects and determine technical and material peculiarities of each provenance and establish history and classification of fabric technology. Here, briefly, the nature of natural fibers and dyes is discussed since they form the majority of museum fabrics at present. 

The classification of fibers has been defined by many people, and it is generally accepted that they can be divided broadly into natural fibers and chemical fibers. Figure 3.2 shows the classification of textile fibers. 

Figure 1.2. Classification of fibers. This is different from the commonly used classification of textile fibers. In the textile fiber classification, fibers are divided into natural fibers and man-made fibers.

One may divide the whole field of fibers in many different ways. One may divide them as natural and synthetic fibers or as potymeric, metallic, and ceramic fibers, etc. One convenient classification is based u[H>n the fiber end use, i.e. apparel and nonapparel fibers. The apparel fibers include synthetic fibers such as nylon, rayon, polyester, spandex, and natural fibers such as wool, cotton, jute, sisal. 

The most fundamental classification of polymers is whether they are naturally occurring or synthetic. Common natural polymers (often referred to as biopolymers) include macromolecules such as polysaccharides e.g., starches, sugars, cellulose, gums, etc.), proteins e.g., enzymes), fibers e.g., wool, silk, cotton), polyisoprenes e.g., natural rubber), and nucleic acids e.g., RNA, DNA). The synthesis of biodegradable polymers from natural biopolymer sources is an area of increasing interest, due to dwindling world petroleum supplies and disposal concerns. 

Inorganic fibers can currently be produced from a wide range of element combinations and further fiber-types are in development (see Section 5.2.7), so that a classification according to chemical composition, as favored by preparative chemists, is not reasonable. Other possible classification criteria are e.g. the production process, the source of the fibers (natural or synthetic), their degree of order (amorphous or crystalline), their thermal stability (27 - 2227°C) or physical properties (tensile strength, elasticity modulus). The boundaries between the individual fiber types are, however, often fluid. 

Classification. Extenders are mainly natural minerals that are converted into a usable form by working natural deposits, separating secondary constituents, and comminution (micronization). Synthetic products such as precipitated carbonates [e.g., calcium carbonicum praecipitatum (ccp), precipitated sulfates (e.g., blanc fixe), precipitated and pyrogenic silica, and silicates are used for optical brightening. Synthetic fibers (generally organic) are used for reinforcement. The classification of extenders used in surface coatings is summarized in Table 4.1. 

Bicomponent stretch fiber such as T400 also can be used in the classification of stretch and recovery properties, which positions it between elastane and standard mechanically textured yams. Self-crimp fibers behave like natural wool with a textured appearance. The crimps are from a composite of two parallel attached fibers with differing shrinkage or expansion properties. Usually, the crimp is generated by either false-twist or air-texturing on the fiber via mechanical deformation of the fiber as a 2D zig-zag crimp. A combination of various polyester materials can be used, for example, PET (polyethylene terephthalate), PTT, and PBT. 

The scientific classification of materials according to their flow behavior corresponds, in a limited sense, to the classification according to their commercial application. A distinction is made here between thermo-plasts, fibers, elastomers, and thermosets. This classification naturally only applies at the application or processing temperature under consideration. 

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