Types of Natural Fibers

By Eman Abdallah Kamel

Eman is a writer and engineer. She received a bachelor’s degree in textile sciences from the Faculty of Applied Arts.

In this article, you will learn about natural fibers, facts, their classification, and types, including plant, animal, and mineral fibers, as well as examples.

Image source: stock.adobe.com

Natural Fibers

Natural fibers are extracted from three subcategories: plant, animal, and mineral fibers. The widely used natural fibers are extracted from plants. Plant fibers consist of five main types, including seed fibers, staple fibers, bast fibers, leaf fibers, grass fibers, and reed fibers.

Natural fibers have many advantages, such as low cost compared with synthetic fibers, low density, light weight, excellent mechanical properties, biodegradability, renewable source, high specific toughness, sound insulation, and non-toxicity.

About 50 million households worldwide are involved in natural fiber production. The largest households are in China, which produces cotton and silk; India, which produces cotton, jute, and coconut; and Bangladesh, which produces jute.

Classification of natural fibers. Image source: Scholarly Community Encyclopedia

Classification

Natural fibers are divided into

Plant Fibers,
Animal Fibers,
Mineral Fibers.

1. Plant Fibers

Plant fibers are classified into five main categories:

Leaf Fibers
Bast Fibers
Seed Fibers
Core Fibers
Grass Straw Fibers

1. Leaf Fibers

It is the strongest plant fiber due to its high lignin content. It is very tough, making it suitable for use in rope production. The leaves are found in the vascular bundles of plants. The fibers are harvested from plants in long, thin bundles, mainly through peeling, where the non-fibrous tissue is scraped away from the plant fibers manually or mechanically. Examples of such fibers are sisal and banana (Musa textilis).

Did You Know?

Sisal is a renewable resource. Sisal absorbs more carbon dioxide than it produces. During processing, it produces organic waste and leaf residues that can generate bioenergy and produce animal feed, fertilizers, and eco-housing materials. At the end of its life cycle, sisal is 100% biodegradable. Sisal also reduces soil erosion through its extensive root system and contributes positively to watershed management.

2. Bast Fibers

Bark fibers are plant fibers collected from the inner bark, or phloem, surrounding the stem of some dicotyledonous plants—for example, linen, jute, hemp, and ramie. Bark fibers are soft and flexible, unlike monocotyledonous leaf fibers, which are tough. The bark fibers are held together in bundles by pectin. The fibers in the bark are separated from the woody pith and sometimes also from the epidermis. The fibers are separated by soaking (retting) with microorganisms on the ground or in water. Or by chemicals or pectin-degrading enzymes. Bark fibers often have a higher tensile strength than other types. Flax is used in high-quality textiles. Jute is used to make ropes, bags, carpets, and handicrafts.

Did You Know?

To boost the production and use of jute, India has decided to use jute as packing material for 100% of grain bags and 20% of sugar bags. The policy is expected to benefit hundreds of thousands of farmer families and 370,000 workers in jute mills. The move will also help protect the environment, as jute is biodegradable.

Cotton is made of long chains of natural cellulose (carbon, hydrogen, and oxygen). Image source: istockphotos.com

3. Seed Fibers

Seed fibers are collected from the seeds of various plants. Seed fibers develop in the plant’s seed pod, from which they must be separated for use. Examples include cotton, kapok, coconut, and milkweed. Cotton is a seed fiber that grows inside the pod or boll of a growing seed and is the most common natural fiber used in garments. Cotton fabric has been used for thousands of years. Cotton fabrics are soft, breathable, moisture-wicking, and comfortable. It can also be easily blended with other fibers. Denim is one of the most popular fabrics around the world. Cotton is used to make a wide range of fabrics. The length of the cotton fiber, which determines its quality, ranges from less than ½ inch to 2 ½ inches. Pima and Egyptian cotton are the two most well-known long-staple kinds of cotton.

Did You Know?

Cotton is water-intensive, requiring at least 20 inches of rain per year, which can be obtained through natural rainfall and/or irrigation. A single cotton shirt requires 2,700 gallons of water, which is about as much water as one person drinks in two and a half years. The process of dyeing fabrics uses 1.3 trillion gallons of water per year.

Microstructure of bamboo fiber. Cellulose, hemicellulose, and lignin make up the majority of bamboo fiber. Image source: longwayeducation.com

4. Core Fibers

Core fibers such as bamboo, jute, hemp, and kenaf fibers. Bamboo fibers come from trees widely distributed in dense forests, especially in China, where there are approximately 40 families and 400 species. Bamboo fiber is used as reinforcement for polymeric materials due to its lightweight, low cost, high strength, and toughness. Bamboo has traditionally been used to make houses, bridges, and boats. Fibers extracted from bamboo are used as reinforcement for making advanced composites in various industries. Bamboo is primarily composed of cellulose, hemicellulose, and lignin. Minor components of bamboo include waxes, resins, and inorganic salts. The primary methods used to produce bamboo fibers are mechanical or chemical. Among the many uses of bamboo fiber are towels, sheets, clothing, jackets, summer clothes, mats, and curtains. Bamboo non-woven fabrics are used to manufacture sanitary pads, masks, mattresses, and food packaging bags.

Straw bales. After the grain is harvested, the remaining portion of the wheat plant is used to make wheat straw fiber, a renewable plant fiber. Image source: istockphotos.com

5. Grass Straw Fibers

Grass fibers such as rice, wheat, and corn. Straw is the residue left after harvesting grains. Straw fibers contain lignin, which gives plants strength. Fibers can be produced after the breakdown of pectin. The fibrous nature of the plant offers fibers their strength. Straw fibers have many uses in construction, insulation, packaging, papermaking, and textiles.

Sheep wool is the most widely used fiber due to its wide availability and low price. Wool fiber is mainly produced in Australia, New Zealand, and China. Image source: Adobe Stock

2. Animal Fibers

After plant fibers, animal fibers are the most commonly used natural fiber. They are made up of proteins. Examples include wool fibers from sheep, goats, llamas, rabbits, and musk oxen. The structure of wool consists of cuticle, cortex, and medulla tissues. Wool fiber contains keratin protein, lanolin (external fat), and a small amount of internal wool fat (about 1.5%). The properties of wool fibers differ from each other. For example, alpaca fibers are lighter and warmer than sheep fibers. Angora fibers obtained from Angora rabbits are fine and soft fibers. Cashmere fibers obtained from cashmere goats are luxurious, soft wool fibers, and qiviut wool is a soft and more expensive fiber. To learn more about different types of wool, visit Types of Wool Fabrics and the Properties of Each Type. Wool fibers make clothing, jackets, blankets, and carpets.

Silk is widely produced in China, South Asia, and Europe. The fiber is extracted from the cocoons of insects after complete metamorphosis. Silk fiber has been used for clothing since ancient times. Silk is very compressible, stretchable, and strong. Silk fibers make women’s clothing, socks, and ties.

Wollastonite is a mineral composed of calcium and silicon oxides (CaSiO₃). It is the subject of development, both as a potential alternative to fired clay and other minerals used in thermoplastics and engineering resins. Also for health reasons. Image source: gwarriors.ca

3. Mineral Fibers

Mineral fibers can be obtained from minerals such as asbestos, ceramic fibers such as fiberglass, and metal fibers such as aluminum fibers. Mineral fibers have high flexibility and excellent resistance to corrosion, moisture, and heat. However, they have poor electrical conductivity and are non-flammable. Mineral fibers have excellent compatibility with building materials such as concrete. For example, asbestos fibers mixed with cement were used to produce asbestos fiber-reinforced roofing sheets to provide fire resistance and insulation, which were very popular among most low-income populations in different countries.

Did You Know?

Many harmful effects of asbestos fibers on human health, such as respiratory problems and lung cancer, were known during the demolition of old structures containing asbestos fibers. Various countries, including Belgium, Brazil, and Canada, have banned the production, marketing, and use of asbestos fibers. Fiberglass and Nomex have taken the place of asbestos fibers.

Sources

Latest Posts

LongWayEducation

The Long Way Education Site path is based on self-learning. Here, you will learn about science, education, and religion. You will also learn about fiber and its manufacture. And different disciplines of engineering, such as mechanical and industrial engineering.