Flax fiber, manufacturing, physical and chemical properties..
M.Sc (C.T) 3rd sem.
The flax fiber is classified, as a natural,
cellulose, bast, multi-cellular fiber. it is
considered to be a heavy fiber, for this reason
that most linen textile materials are of light
construction. Thick linen textile materials would
be uncomfortably heavy to wear.
The macro-structure of flax-
The flax fiber is a thick, regular fiber with a
It ranges in length from about 10cm to 100 cm,
averaging about 50cm in length.
As the flax fiber is a strand of cells, it thickness
depends upon the number of these cells, about 3-6
cells constitute a fiber cross section.
The flax cells are about 25mm long and 10µm to
20µm thick. This would be give an average fiber
thickness ranging from about 40µm to 80µm.
Its fiber length to breadth ratio is 15000:1 for
the longest and the best flax and 1500:1 for
Short flax fibers .
The color of flax varies from light blond to grey
blond, the particular shade resulting from the
agricultural and climatic conditions under which
it was grown and the quality of retting.
The subdued luster of flax is due to its long
regular fiber surface, which is coated with a film
wax. This enables a significant amount of the
incident light to be reflected, resulting in the
There may be up to 80 nodes in a single flax
fiber cell. The length of the node indicates
the width or thickness of the fiber cell.
Where ever a node occurs, it indicates a
change in the spiral direction of the fibrils
which constitute the cell walls.
Such spiraling imparts strength to the cell
and, hence, to the flax fiber
Microscopic appearance of flax-
The cross markings, known as nodes, on flax
fibers give them their characteristic microscopic
The micro-structure of flax-
The flax fiber cell is covered with a wax film.
The cell walls of flax are constructed of
spiraling fibrils composed of cellulose polymers.
On the whole, the flax cell is more sturdily
constructed then the cotton cell, as indicated by
the former’s thicker cell walls.
This explains, in part, the greater tenacity of
flax compared with cotton.
The polymer system-
The flax polymer and its polymer system-
it has a degree of polymerization of about 18000.
This means the flax polymer is about 18000nm long, and
about 0.8nm thick.
The polymer system of flax is more crystalline , because of
its longer polymers, spirals about each other at
approximately 6° to the fiber axis, thereby contributing
towards the tenacity and durability of fiber.
The greater crystallinity of flax fibers is demonstrate by the
fact that they are stronger, crisper and stiffer to handle,
and textile materials wrinkle more readily than those of
Flax is a very strong fiber because it’s very crystalline
polymer system permits its extremely long polymers to
form more hydrogen bonds than cotton polymers.
The very inelastic nature is due to very crystalline
It tends to lock its polymers into position with the aid of
the countless hydrogen bonds which form between the
Flax will resist being flexed or bent,. When these are
bent or flexed, their polymers are liable to break leading
to fractures in the polymer system.
Flax fiber is very absorbent,
Owing to the countless polar –OH groups in its
polymers, these attract water molecules, which are
Aqueous swelling of the flax fiber is due to a
separation or forcing apart of polymers by the
water molecules in the amorphous regions only.
The polarity of the water molecules, attracted to
the hydroxyl groups on the polymers, dissipates
any static charge which might develop.
Flax has the best heat resistance and
conductivity of all the commonly used textile
fibers. No satisfactory explanation can be
offered for this.
Excessive application of heat energy causes
the flax fiber to scouch, char and burn, This is
an indication that flax is not thermoplastic,
which may be attributed to the extremely long
fiber polymers and the countless hydrogen
bonds they form.
Effect of acids
flax fibers are weakened and destroyed by
Acidic conditions hydrolyze the flax polymer at
the glycoside oxygen atom, which links the two
glucose units to form the cellobiose unit.
Mineral or inorganic acids, being stronger that
organic acids, will hydrolyze the flax polymer
linen textile materials are not mercerized .
Normal laundering will result in alkaline
hydrolysis of the waxes and gums bonding
the cells forming the flax fiber together. This
results in cell ends projecting above the
surface of linen textile materials, and is
referred to as cottonising of linen.
Several cottonising will cause a noticeable
weakening of the linen textile material.
Effect of bleaches-
The most common bleaches used on flax textile
materials are sodium hypochlorite and sodium
These two bleaches are examples of oxidizing
bleaches, which is mostly used for flax textile
materials. Oxidizing bleaches are so called
because they liberate oxygen which does the
Manufacture of Linen
1. Collection of plants- when the
stems of the plant turns yellow at the
seeds turn green to pale brown. The
plants are pulled out by the roots.
These are tied into bunches.
2. Drying and rippling- after pulling the
Flax, plant is tied in bundles and left to dry for
few days. The leaves and seeds are
removed from the stems by a process
called Rippling. For this, the head of the
stem is passed through coarse comb. After
the removal of leaves and seeds, the stems
are again tied up in bundles. Seeds are
used for the production of Linseed oil.
3.Retting- this is an important process. The
fleshy part of the stem is rotted by contact with
water. Retting is a ferment process where the
Pectin Ovurum(Pectin eater) bacteria eat the
gum(pectin) which bind the fiber to the stem.
There are 5 method of retting-
A. Dew retting-
stems are spread out in fields and are exposed
to rain, sun and dew for several weeks, until,
the stalk begins to separate from the fiber. It
takes around 15-30 days. Because of long
exposure to the sun and other natural
conditions, causes to discoloration of the fiber.
B. Water retting- the bundle of
the stems are kept in running or
segmented water for about 2
weeks . Swift running of water
carries away the bacteria and
thus slow down the fermentation. The stem
are covered with straw and stones are put on the
straw to give extra weight. After 2 weeks the
(upper portion of stem) separates out from the
C. Wooden vat retting- the stems are steeped
in water at the controlled temperatur75°-90° in
a Vat or in a container until the stems get soft.
This is a fast process and the easiest method of
retting and the quality of the fibers are good
from this process.
D.Chemical retting- in this process the stems
are treated with mild/dilute conc. Acid and
alkalis then the fibers are easily removed from
E.Enzyme retting- enzyme retting is the safest
and fastest process of retting, in this process
the fibers can be taken out from the stems
4.Breaking and scutching- when
the stems are completely dry linen fiber
are separated from these stems when
the decomposed woody tissue is dry.
It is crushable by passing through iron
Rollers. The breaking operation break
the outer stalk. It reduces the stalk
to small pieces of bark called slivers. Scutching
is done with the help of scutching machine
which removes the broken slivers by means of
rotating wooden peddles, thus releasing the flax
fiber from the stem or it separates the fibers
from woody stalk
5. Hackling or combing and spinning- during this
process series of iron combs are used, ranging from coarse to
fine. Fibers are pulled through the teeth of combs, beginning
with the coarse one. The short fibers break off used for inferior
quality Lenin called Tow linen. Then the spinning process is
Tow-lines Long staple or line
Spinning Drawints Raning
Coarse yarn(linen) Rove
fine yarn (linen)
6.weaving, finishing & dyeing- bleaching
is given to the yarn and later on dyeing is
done. The reason being the Linen yarn is in
natural color i.e. grey or yellowish grey.
Dyeing can not be done directly because it
is not white in color. That is why bleaching
is done before dyeing.