mahmud_ Fiber in Nature _01

Fibers in nature

Overview

Fiber, also spelled fibre, is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread. They are very important in the biology of both plants and animals, for holding tissues together. Human uses for fibers are diverse. They can be spun into filaments, string or rope, used as a component of composite materials, or matted into sheets to make products such as paper or felt. Fibers are often used in the manufacture of other materials. Synthetic fibers can be produced very cheaply and in large amounts compared to natural fibers, but natural fibers enjoy some benefits, such as comfort, over their man-made counterparts.
( source: http://en.wikipedia.org/wiki/Fiber)

Classification

Fundamentally, Fibers are of two types: A) natural fiber B)Human-made fiber. The earliest evidence for humans using fibers is the discovery of wool and dyed flax fibers found in a prehistoric cave in the Republic of Georgia that date back to 36,000 BP [1,2]
(source: 1.Balter M. (2009). Clothes Make the (Hu) Man. Science,325(5946):1329
2. Kvavadze E, Bar-Yosef O, Belfer-Cohen A, Boaretto E,Jakeli N, Matskevich Z, Meshveliani T. (2009)

A) Natural fiber

Natural fibers are made from plant, animal and mineral sources. Natural fibers can be classified according to their origin which is given below:

A.1) Vegetable fiber:

Vegetable fibers are generally comprised mainly of cellulose: examples include cotton, jute, flax, ramie, sisal, and hemp. Cellulose fibers serve in the manufacture of paper and cloth. This fiber can be further categorized into the following:

1. Seed fiber: Fibers collected from seeds or seed cases. e.g. cotton and kapok

2. Leaf fiber: Fibers collected from leaves. e.g. fique, sisal, banana and agave.

3. Bast fiber or skin fiber: Fibers are collected from the skin or bast surrounding the stem of their respective plant. These fibers have higher tensile strength than other fibers. Therefore, these fibers are used for durable yarn, fabric, packaging, and paper. Some examples are flax, jute, kenaf, industrial hemp, ramie, rattan, and vine fibers.

4. Fruit fiber: Fibers are collected from the fruit of the plant, e.g. coconut (coir) fiber.

5. Stalk fiber: Fibers are actually the stalks of the plant. E.g. straws of wheat, rice, barley, and other crops including bamboo and grass. Tree wood is also such a fiber.

A.2) Animal fiber:

Animal fibers generally comprise proteins; examples include silk, wool, catgut, angora, mohair and alpaca. The classification of animal fiber is given below:

1. Animal hair (wool or hairs): Fiber or wool taken from animals or hairy mammals. e.g. sheep's wool, goat hair (cashmere, mohair), alpaca hair, horse hair, etc

2. Silk fiber: Fiber collected from dried saliva of bugs or insects during the preparation of cocoons.

3. Avian fiber: Fibers from birds, e.g. feathers and feather fiber.

B) Human-made fiber

Synthetic or man-made fibers generally come from synthetic materials such as petrochemicals. But some types of synthetic fibers are manufactured from natural cellulose, including rayon, modal, and the more recently developed Lyocell. Cellulose-based fibers are of two types, regenerated or pure cellulose such as from the cupro-ammonium process and modified cellulose such as the cellulose acetates.

Classification of human-made fiber is given below:
1) Cellulose fiber
2) Mineral fiber
3) Polymer fibers
4) Micro fibers

( source: www. wikipedia.org)

Here, basically, we will concentrate on Natural Fibers.