Natural Fibers

Textile fibers are normally broken down into two main classes, natural and man-made fibers. All fibers which come from natural sources (animals, plants, etc.) and do not require fiber formation or reformation are classed as natural fibers. 

Natural plant and animal fibres have provided the raw materials to meet our fibre needs. No matter which climatic zone humans settled, they were able to utilize the fibres 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 fibres. Natural fibre is any hair like raw material directly obtainable from animals, vegetables or mineral source and convertible into nonwoven fabrics such as felt or after spinning into yarns or woven cloth. -

Natural fibres from vegetable fibres are obtained from the various parts of the plants. These fibres are classified into three categories depending on the part of the plant from which they are extracted. Those three categories are bast or stem fibres (jute, mesta, banana etc.), leaf fibres (sisal, pineapple, screw pine etc.) seed fibres (cotton, coir, old palm etc.). Many of the plant fibres such as coir, sisal, jute, banana, pineapple and hemp find applications as a resource for industrial materials. Properties of natural fibres depend mainly on the nature of the plant, locality in which it is grown, age of the plant, and the extraction method used. 

A natural fibre also may be further defined as a agglomeration of cells in which the diameter is negligible in comparison with the length. In some applications, natural fibres are replacing glass fibres in reinforced polymers, where the tensile strength of the fibre is not as important as the specific stiffness. Natural fibre 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:

• Fibre occurring on the seed (raw cotton, java cotton
• Phloem fiber (flax, ramie, hemp, jute) 
• endon fibre from stem or leaves (manila hemp, sisal hemp etc) 
• Fibre occurring around the trunk (hemp palm) 
• Fibre of fruit/ nut shells (coconut fibre – 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. 

Thermal recycling is possible, where glass causes problems in combustion furnaces. 

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 

It is a renewable resource, the production requires little energy, CO2 is used while oxygen is given back to the environment. 

Price can fluctuate by harvest results or agricultural politics. 

Lower durability, fibre treatments can improve this considerably. 

Moisture absorption, which causes swelling of the fibres. 

Lower strength properties, particularly its impact strength.