Natural Fibers

 

Natural Fibers

All fibers which come from natural sources (animals, plants, etc.) and do not require fiber formation or reformation are classed as natural fibers. The natural fibers are vegetable, animal, or mineral in origin. Some of the natural fibers like vegetable fibers are obtained from the various parts of the plants. They are provided by nature in ready-made form. It includes the protein fibers such as wool and silk, the cellulose fibers such as cotton and linen, and the mineral fiber asbestos.

Natural plant and animal fibers have provided the raw materials to meet our fiber needs. No matter which climatic zone humans settled, they were able to utilize the fibers of native species to make products such as clothes, buildings, and cordage. The use of composite materials dates from centuries ago and it all started with natural fibers.

Natural fibers from vegetable fibers are obtained from the various parts of the plants. These fibers are classified into three categories depending on the part of the plant from which they are extracted. Those three categories are bast or stem fibers (jute, mesta, banana etc.), leaf fibers (sisal, pineapple, screw pine etc.) seed fibers (cotton, coir, old palm etc.).

Many of the plant fibers such as coir, sisal, jute, banana, pineapple, and hemp find applications as a resource for industrial materials. Properties of natural fibers depend mainly on the nature of the plant, locality in which it is grown, the age of the plant, and the extraction method used.

A natural fiber also may be further defined as an agglomeration of cells in which the diameter is negligible in comparison with the length. In some applications, natural fibers are replacing glass fibers in reinforced polymers, where the tensile strength of the fiber is not as important as the specific stiffness. Natural fiber reinforced polymers are generally restricted for use in non-structural products.

In contrast, fibers from natural sources are provided by nature in ready-made form.

Natural fibers include the protein fibers such as wool and silk, the cellulose fibers such as cotton and linen, and the mineral fiber asbestos.

Plant fibers can be further on classified as:

• Fiber occurring on the seed (raw cotton, java cotton)
• Phloem fiber (flax, ramie, hemp, jute)
• Tendon fiber from stem or leaves (Manila  hemp, sisal hemp etc)
• Fiber occurring around the trunk (hemp palm)
• The fiber of fruit/ nut shells (coconut fiber – Coir)

Cotton and Linen (made from Flax pant) are the most important among them.

Advantages and Disadvantages of Natural Fibres

Advantages	Disadvantages
Producible with low investment at low cost, which makes the material an interesting product for low-wage countries.	Price can fluctuate by harvest results or agricultural politics.
	Lower durability, fiber treatments can improve this considerably.
Thermal recycling is possible, where glass causes problems in combustion furnaces.
	Moisture absorption, which causes swelling of the fibers.
Low specific weight, which results in a higher specific strength and stiffness than glass. This is a benefit especially in parts designed for bending stiffness	Lower strength properties, particularly its impact strength.
It is a renewable resource, the production requires little energy, CO2 is used while oxygen is given back to the environment.