Natural Cellulose Fibers
Cellulose is a fibrous material of plant origin and the basis of all
natural and man-made cellulosic fibers. The natural cellulosic fibers
include cotton, flax, hemp, jute, and ramie. Cellulose is a polymeric
sugar polysaccharide) made up of repeating 1,4-8-an hydro glucose units
connected to each other by 8-ether linkages. Strong intermolecular
forces between chains, coupled with the high linearity of the cellulose
molecule, account for the crystalline nature of cellulosic fibres.
Cellulosic Fibers
The natural fibers are vegetable, animal, or mineral in origin.
Vegetable fibers, as the name implies, are derived from plants. The
principal chemical component in plants is cellulose, and therefore they
are also referred to as cellulosic fibers.
The fibers are usually bound by a natural phenolic polymer, lignin,
which also is frequently present in the cell wall of the fiber; thus
vegetable fibers are also often referred to as lignocellulosic fibers,
except for cotton, which does not contain lignin.
Cellulose is a fibrous material of plant Origin and the basis of all
natural and man-made cellulosic fibers. The natural cellulosic fibers
include cotton, flax, hemp, jute, and ramie. The major man-made
cellulosic fiber is rayon, a fiber produced by regeneration of dissolved
forms of cellulose.
Cellulose is a polymeric sugar (polysaccharide) made up of repeating
1,4-8-an hydro glucose units connected to each other by 8-ether
linkages.
The long 1inear chains of cellulose permit the hydroxyl functional
groups on each anhydrous glucose unit to interact with hydroxyl groups
on adjacent chains through hydrogen bonding and van der Waal s forces.
These strong intermolecular forces between chains, coupled with the high
linearity of the cellulose molecule, account for the crystalline nature
of cellulosic fibers.
Classification of Vegetable Fibers
Vegetable fibers are classified according to their source in plants as follows:
(1) The bast or stem fibers, which form the fibrous bundles in the inner
bark (phloem or bast) of the plant stems, are often referred to as soft
fibers for textile use;
(2) The leaf fibers, which run lengthwise through the leaves of
monocotyledonous plants, are also referred to as hard fibers; and
(3) The seed-hair fibers, the source of cotton, which is the most
important vegetable fiber. There are >250,000 species of higher
plants; however, only a very limited number of species have been
exploited for commercial uses (<0.1%).
Seed Fibers
· Cotton is
the most commonly used natural cellulosic fiber. Cotton fibers grow
from the seeds in the boll (seedpod). Each boll contains seven or eight
seeds, and each seed may have up to 20,000 fibers growing from it.
· Coir is
from the fibrous mass between the outer shell and husk of coconuts. It
is a stiff fiber. It is usually used to make highly durable indoor and
outdoor mats, rugs, and tiles.
· Kapok fiber
is from the seed of the Java or Indian kapok tree. The fiber is soft,
lightweight, and hollow. It breaks down easily and it is difficult to
spin into yarns. It is used as fiberfill and as the stuffing for
pillows. It used to be used as a stuffing for lifejackets and the
mattresses on cruise ships because it is very buoyant.
· Milkweed has properties similar to those of kapok.
Bast Fibers
· Flax is
one of the oldest textile fibers, but its use has declined since the
invention of power spinning for cotton. Flax fabric is linen, although
the word linen is now often used to refer to table, bed, and bath
fabrics made from other materials
· Ramie fibers
are 4 to 6 inches long. The fibers are whiter and softer than flax.
Ramie does not retain dyes well unless it is dry-cleaned. Ramie is
strong for a natural fiber, but it lacks resiliency, elasticity, and
elongation potential. It is resistant to mildew, insects, and shrinkage.
It is used for apparel, window treatments, ropes, paper, and table and
bed linens.
· Hemp is
similar to flax. The fibers range in length from 3 to 15 feet. Hemp
production is illegal in the U.S. Hemp has a low environmental impact;
it does not require pesticides. It produces 250% more fiber than cotton
and 600% more fiber than flax on the same amount of land. Hemp plants
can be used to extract zinc and mercury pollutants from soil. Hemp is
used for ropes, apparel, and paper. Potheads are willing to pay inflated
prices for hemp apparel because it is related to the marijuana plant.
· Jute is
one of the cheapest textile fibers, and one of the weakest cellulosic
fibers. Jute has poor elasticity, elongation, sunlight resistance,
mildew resistance, and colorfastness. It is used to produce sugar and
coffee bagging, carpet backing, rope, and wall coverings. Burlap is made
from jute.
Leaf Fibers
· Piña fibers
are from the leaves of the pineapple plant. It is used to make
lightweight, sheer, stiff fabrics for apparel, bags, and table linens.
It is also used to make mats.
· Abaca is
from a member of the banana tree family. The fibers are coarse and very
long (up to 15 feet). It is a strong, durable, and flexible fiber used
for ropes, floor mats, table linens, apparel, and wicker furniture.
No comments:
Post a Comment