Natural fibers
Natural
fibers are fibers that are produced by geological processes or from the bodies
of plants or animals. These can be used as a component of composite materials,
where they affect the adaptive properties of fibers. Natural fibers can also be
matted on paper or felt sheets.
Natural
fibers are good sweat absorbers and are available in a variety of textures.
Cotton fibers made from cotton plants, for example, produce fabrics that are
light in weight, soft in texture, and can be made in a variety of shapes and
colors. Clothing made of natural fibers, such as cotton, is often preferred by
people living in hot and humid climates over clothing made of synthetic fibers.
It
can be used for high-tech applications, such as composite parts for automobiles.
Compared to strong composites with glass fiber, natural fiber composites have
advantages such as low density, good thermal insulation, and reduction of skin
irritation. Moreover, unlike glass fibers, natural fibers can be broken down by
bacteria once they are no longer used.
Natural fibers properties
i.
Natural fibers are obtained from nature.
ii.
The length of the fiber cannot be controlled it's natural.
iii.
No spinning process is needed.
iv.
Fabrics made up of natural fibers are comfortable in wearing.
v.
Coloration is easy.
vi.
It can be used as a component of composite materials, where the orientation of
fibers impacts the properties.
vii.
It can also be matted into sheets to make paper or felt.
viii.
It has good sweat absorbents and can be found in a variety of textures.
ix.
Natural fibers produce fabrics that are light in weight, soft in texture, and
can be made in various sizes and colors.
Natural fiber list
Natural fiber lists are as follows-
A. Plant Fiber: Abacá, Bagasse, Bamboo, Coir, Cotton, Jute, Kapok, Kenaf, Piña, Pine, Raffia, Fique, Flax, Hemp, Ramie, Sisal, Wood.
B. Animal Fiber: Silk, Sinew, Spider silk, Wool, Alpaca, Angora, Byssus, Camel hair, Cashmere, Catgut, Chiengora, Guanaco, Human hair, Llama, Mohair, Pashmina, Qiviut, Rabbit, Vicuña, Yak.
C. Mineral Fiber: Asbestos
Natural fiber types
There
is most common classification for natural fibers is by botanical type and
animal fiber. Using this term, there are six basic types of natural fibers
those are botanical types such as bast fiber; Leaf fiber; Seed fiber; Core
fiber; Grass and reeds; And all other types such as wood and roots.
1.
There are six basic types of natural fibers according to their botanical origin
those are as follows-
A.
Bast fibers such as jute, flax, hemp, ramie, and kenaf.
B.
Leaf fibers such as abaca, sisal, agave, and pineapple.
C.
Seed fibers such as coir, cotton, oil palm, rice hulls, and kapok.
D.
Core fibers such as kenaf, hemp, and jute.
E. Grass and reed fibers such as bagasse, bamboo, Johnson grass,
wheat, corn, and rice.
F.
Other types such as wood and roots.
A. Bast fibers
Bast fibers are plant fibers that are collected from phloem or bast that surround the stems of specific bicellular plants. It supports the phloem's conductive cells and strengthens the stem. Some economically important bast fibers are derived from herbs grown in agriculture, such as flax, hemp, or Ramie, but also from wild plants such as bast fiber, stinging nettle, and lime or linden, willow, oak, and wisteria, and mulberry has been used in the past. Bast fibers are classified as soft fibers and flexible.
i. Jute fiber
Jute
fiber is derived from plants of the genus Corchorus, the family Malvaceae. Jute
is a lignocellulosic fiber which is partly a textile fiber and partly wood. It
falls into the category of bust fibers which means fibers collected from the
bust or plant skin. The chemical composition of jute fiber includes cellulose
(64.4%), hemicellulose (12%), pectin (0.2%), lignin (11.8%), water-soluble
(1.1%), wax (0.5%), and water (10%). Jute fiber consists of a few cells. These
cells are made up of crystalline microfibrils based on cellulose, which is
attached to a complete layer by amorphous lignin and hemicellulose. One primary
and three secondary cell walls, multiple such celluloses, and
lignin/hemicellulose layers combine to form multiple-layer compounds.
ii. Flax
As
a bast fiber, flax is one of the oldest textile fibers. Evidence of its use has
been found in habitats on prehistoric lakes in Switzerland. Fine linen cloth,
indicating a high degree of skill, has been discovered in ancient Egyptian
tombs. Phoenician merchants apparently brought linen from the Mediterranean to
Gaul and Britain, and the Romans introduced linen-making throughout their
empire. In the 17th century, the German state and Russia were the main sources
of raw materials, and the linen industry was established in the Netherlands,
Ireland, England, and Scotland. The expansion of the cotton industry in North
America diminished the importance of linen. Fiber color from buff to gray, best
quality creamy white. Fine grades of flax fibers are used to make woven fabrics
and lace for clothing and household furniture. Lower grades are used for
products that require strength and moisture resistance such as canvas, yarn,
fire hoses, bagging, industrial sewing threads, and fishnet.
iii. Hemp
Hemp
originates in Central Asia and cultivation for fiber was recorded in China in
2800 BC and was practiced in the Mediterranean countries of Europe at the
beginning of the Christian era, spreading to the rest of Europe in the Middle
Ages. Fibers are obtained by subjecting stalks to a variety of activities -
including ratings, drying, and crushing - and a shaking process that completes
the separation from the wood part, leaving long fairly straight fibers or
lines. Fiber strands, usually more than 1.8 m long, are made up of individual
cylindrical cells with an irregular surface. Fiber is longer and less flexible
than flax, is usually yellow, green, dark brown, or gray and, because it cannot
be easily bleached insufficiently light shades, is rarely dyed. It is strong
and durable and is used for cordage, for example, twine, yarn, rope, wire, and
string, and for thick fabrics such as synthetic sponges and sacks, and canvas.
B. Leaf fibers
Leaf
fibers are mainly obtained from sword-shaped leaves which are a major source of
thick, fleshy, and often hard surfaces, such as plants of the agave subfamily.
The leaves are strengthened and supported by fiber bundles, often a few feet
long, joined together by many overlapping sclerenchyma cells, or true plant
fibers, adhesive. The fibers usually exceed the length of the leaf and are most
dense near the underside of the leaf. The fibers are collected from the tree in
long, thin bundles, mainly through the process of decorating where the
non-fibrous tissues are scraped from the tree fibers by hand or by machine. In
most cases, the leaves have to be hand-picked from the tree before they can
mature through the pulp, which makes collecting stiff fibers a very
energy-intensive and time-consuming task. Leaf fiber or hard fiber is a type of
plant fiber that is mainly used for cordage. These are the strongest of the
plant fibers which is probably due to the increase in their lignin content when
compared to other groups of plants. These are generally characterized as very
stiff and rigid which lends them to use in the manufacture of ropes on fibers
of other plants such as clothing or paper. Sisal and abaca or banana fibers are
the primary leaf fibers that are collected and sold.
i. Sisal fiber
A sisal is a group of fibers extracted from the leaves of plants belonging to the
agave family. It is one of the most widely used natural fibers and is easily
cultivated. Sisal fibers scraped from fresh leaves cut from trees are hard and
strong with low elasticity. It is important in making items such as matting,
rough handbags, rope, cordage, especially marine rope, and carpeting. Sisal
cloth is also used to polish materials. Around 4.5 million tons of sisal fiber
is produced every year worldwide. Sisal represents 2% of the world's plant
fiber population.
ii. Abacá/Banana fiber
Abacá
is a native banana species of the Philippines, grown as a commercial crop in
the Philippines, Ecuador, and Costa Rica. Also known as Manila hemp, this plant
has a lot of economic importance, it is collected for its fiber, extracted from
the leaf stems. Abaca is a traditional source of bright fibers made by hand
from a variety of indigenous textiles in the Philippines, such as t'nalak, as
well as from the colonial era, known as nips. They are also the source of
fiber for sinamáy, a loosely woven hard material used in textiles as well as
traditional Philippine millinery. The fiber was mainly used to make yarn and
rope; now mostly pulp is used in various specialized paper products including
tea bags, filter paper, and banknotes. It is classified as a hard fiber,
including coir, henequin, and sisal.
C. Seed fibers
The
fibers that are collected from the seeds of different plants are called seed
fibers.
i. Cotton fiber
Cotton
is a soft, fluffy staple fiber that grows in a bowl or protective field around
the seeds of the Gossypium genus of the Malvaceae family Malvaceae. The fiber
is almost pure cellulose and can contain a small percentage of wax, fat,
pectin, and water. Under natural conditions, cotton balls will increase seed
dispersal. Fiber is often spun into thread or yarn and used to create a soft,
breathable, and durable textile. The use of cotton for cloth has been known
since prehistoric times; Pieces of cotton cloth dating to the 5th millennium BC
have been found in the Indus Valley Civilization, as well as cloth remnants from
6000 BC in Peru. Although cultivated since ancient times, it was the invention
of the cotton gin that reduced production costs that led to its widespread use and is the most widely used natural fiber fabric in clothing today.
ii. Coir fiber
Coir
fiber is a natural fiber extracted from coconut husk and used in products such
as floor mats, doormats, brushes, and mattresses. It is the hard, inner shell
of a coconut and the fibrous material found in the outer shell. Other uses of
brown coir made from ripe coconut are in upholstery padding, sacking, and
horticulture. White coir fiber collected from immature coconuts is used to make
fine brushes, ropes, strings, and fishing nets. It has the advantage of not
sinking, so boats and buoys can be used for long lengths in deep water without
the extra weight of a tow.
E. Grass and reed fibers
i. Grass fibers
Grass
fibers are another group of monochromatic fibers, where the whole stem is
joined to the leaf and used to make paper. Grass fiber has the potential to be
used in composite materials for industrial applications, including automotive,
lightweight building, packaging, and aerospace structures. The composites still
do not have any standard fiber content, but many researchers have reported that
up to 40% fiber loading is considered optimal in polymer composites which gives
better mechanical properties. Moreover, grass fiber is reasonably similar
to other natural fibers already used for industrial applications. Natural fiber
composites have been developed for a variety of industrial products due to
their mechanical properties, biodegradability, and environmental durability.
The main goals of the aerospace industry are to reduce costs, carbon dioxide
emissions, and fuel costs, thus the application of natural fibers as
reinforcement in polymer composites has attracted much attention in the
industry.
ii. Bamboo fiber
Bamboo
textile is clothing made from any fabric, yarn, or bamboo fiber. Although
historically used only for structural elements, such as hull and corset
ribs, various technologies have been developed in recent years to allow bamboo
fiber to be used for a wide range of textile and fashion applications. Examples
include bedding like shirt tops, pants, and socks for adults and children, as well
as sheets and pillow covers. Bamboo yarn can be blended with other textile
fibers such as hemp or spandex. Bamboo fiber is an alternative to plastic that
is renewable and can be replenished at a faster rate. Modern garments labeled
bamboo are usually made of viscose rayon, a fiber that dissolves cellulose in
bamboo and then extracts it to form a fiber. This process removes the natural
properties of bamboo fiber, making it identical to rayon from other cellulose
sources.
F. Wood and root fibers
Wood
fibers are usually cellulosic materials extracted from wood and used to make
materials like paper. The final paper products such as paper, paperboard,
tissue, cardboard, etc. indicate the species or mixture of species, which is
most suitable for providing the desired sheet properties, and the necessary
fiber processing such as chemical treatment, heat treatment, mechanical
brushing, or refining, etc. Wood fiber can be extracted as a primary product,
or collected during wood milling. Wood fibers can also be recycled from used
paper materials.
2. Animal fibers
The
fibers that are collected from animals are called animal fibers. Animal fibers
are natural fibers that are made up of specific proteins. Examples include
silk, wool with hair/fur, and feathers. The most widely used animal fibers in
both the manufacturing world, as well as hand spinners, are domestic sheep wool
and silk. Also, very popular are Angora goat alpaca fiber and mohair. Unusual
fibers such as rabbit angora wool and Chiengora are found in dogs but are
rarely used for mass production.
i. Silk fiber
Silk fiber is a natural protein fiber that can be woven into textiles. Silk
protein fibers are mainly composed of fibroin and cocoons are made by the
larvae of some insects. The most well-known silk is found in captive mulberry
silkworm larvae cocoons. The shimmering appearance of silk is due to the
triangular prism-like structure of silk fiber, which allows the silk fabric to
reflect light from different angles, thus creating different colors. Silk is
one of the strongest natural fibers, but when it gets wet it loses up to 20% of
its strength. It has a good moisture recovery of 11%. Its elasticity is
moderate to poor: if stretched even in small amounts, it stays stretched. It
can become weak when exposed to too much sunlight. It can be attacked by
insects, especially if left dirty. Fabrics often made from silk include
charmeuse, habutai, chiffon, taffeta, crêpe de chine, dupioni, noil, tussah,
and shantung. It is often used for clothing such as shirts, ties, blouses,
formal wear, high-fashion clothing, lining, underwear, pajamas, dresses, dress
suits, sun clothing, and earlier folk clothing.
ii. Wool fiber
Wool
fiber is a textile fiber derived from sheep and other animals those are
including cashmere and mohair from goats, qiviut from muskoxen, hide and fur
clothing from bison, angora from rabbits, and other types of wool from
camelids. Wool contains protein with a small percentage of lipids. In this
regard, it is chemically different from another widely used textile, cotton,
which is mainly cellulose. The hairs are produced by follicles which are small
cells located in the skin. Primary follicles produce three types of fibers like
kemp, medullated fibers, and true wool fibers. Secondary follicles produce only
true wool fibers. The modulated fibers share almost identical features with the
hair and are long but lack crimp and elasticity. The kemp fibers are very thick
and protrude. Merino wool is usually 90-115 mm in length and very delicate. The
best and most valuable wool comes from Merino hoggets. Wool taken from sheep
produced for meat is usually thick and contains fibers 40-150 mm long. If the
sheep is pressed while raising the fleece, the wool may be damaged or broken,
creating a thin spot where the wool is likely to break. Wool is also divided
into grades based on the diameter of wool measured in microns and its style.
These grades may vary depending on the type or purpose of the wool. For
blankets, horse rugs, jeans, rugs, insulation, and upholstery wool are used.
3. Mineral fibers (Asbestos)
Asbestos
is a naturally occurring fibrous silicate mineral. Six types, all composed of
long and thin fibrous crystals, each fiber is composed of many microscopic
"fibrils" that can be released into the atmosphere through friction
and other processes. Respiratory asbestos fibers can cause a variety of serious
lung conditions, including mesothelioma, asbestosis, and lung cancer, so it is
now notorious as a health and safety risk. Archaeological evidence suggests
that asbestos was used to strengthen ceramic vessels in the Stone Age, but
large-scale mining for its desired physical properties began in the late 19th
century when builders and manufacturers began using asbestos. Asbestos is an
excellent electrical insulator and is extremely heat-resistant, so for most of the
20th century, it was widely used around the world as a building material until
its effects on human health were recognized in the 1970s. The use of asbestos
for construction and fire protection has been outlawed in many countries.
Natural fiber advantages
i. The natural fiber is environmentally friendly
ii. It is fully biodegradable.
iii. It is a non-toxic fiber
iv. It is easy to handle
v. It is non-abrasive during processing and use.
vi. It is low-density/lightweight.
vii. It is compostable fiber
viii. Source of income for rural/agricultural community
ix. It has good insulation power against heat and noise.
x. It has a renewable abundant and continuous supply of raw materials.
xi. When burning does not produce poisonous gases.
xii. It is easily affordable.
xiii. It absorbs sweat and water and hence such clothes are comfortable for summer months.
xiv. It is safe for human skin.
Natural fiber disadvantages
i. Natural fiber is very expensive.
ii. It shrinks due to aggressive washing.
iii. Low tenacity while synthetic medium.
iv. It has a low degree of resiliency
v. Its production cannot be completely controllable
vi. The availability of natural fibers is affected by natural calamities and varies in nature.
vii. Land use in natural fiber production is also essential for the growth of agricultural products.
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