Flax fiber is classified as a natural, cellulose, bast fiber that is considered heavy. It ranges from 10-100cm in length with a thickness of 40-80μm. Flax has a subdued luster due to its wax coating and contains spiraling fibrils made of cellulose polymers within thick cell walls, contributing to its strength. Flax is strong due to its highly crystalline polymer system forming many hydrogen bonds. It is very inelastic and hygroscopic, absorbing water through hydroxyl groups. Flax has good heat resistance conducted through its long polymers linked by hydrogen bonds. Acids hydrolyze flax's cellulose polymer while bleaches like sodium hypochlorite and perborate

1. Flax (linen) fiber
Prepared by:Hailay kidane
1st
year Ms.c student
ID: SGSR/0178/09
Submitted to: Adane Haile (Asst.Professor)

2. 1
The flax fiber is classified, as 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.
Fig 1 Flax structure from the stem to the cellulosic fibrils
Flax Fiber morphology-
The macro-structure of flax- The flax fiber is a thick, regular fiber with a subdued luster. 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 giving 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 subdued luster.
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
Flax fiber

3. 2
Microscopic appearance of flax-The cross markings, known as nodes, on flax fibers give them
their characteristic microscopic appearance.
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
crystalline 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 cotton fibers.
Physical properties-
Tenacity-
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.

4. 3
Elastic-plastic nature-
The very inelastic nature is due to very crystalline polymer system. It tends to lock its polymers into
position with the aid of the countless hydrogen bonds which form between the polymers. 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.
Hygroscopic nature-
Flax fiber is very absorbent, Owing to the countless polar –OH groups in its polymers; these attract
water molecules, which are also polar. 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.
Thermal properties-
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.
Chemical properties-
Effect of acids
flax fibers are weakened and destroyed by acids. 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 more rapidly.
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
per borate. 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
actual bleaching.

5. 4
Manufacture of Linen
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
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 Overrun (Pectin eater) bacteria eat the gum
(pectin) which binds the fiber to the stem. There are 5 method of retting-
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.
Water retting- the bundle of the stems are kept in running or segmented water for about
2weeks. Swift running of water carries away the bacteria and thus slow down the fermentation.
The stem bundles are covered with straw and stones are put on the straw to give extra weight.
After 2 weeks the stalks (upper portion of stem) separates out from the fiber and the bundles are
taken out of the water and left to dry.
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 the stems.
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 within few hours.
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 breaks 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

6. 5
Hackling or combing and spinning- during this process series of iron combs are used, ranging
from course 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 carried out.
Reference
1) Hand book of fiber chemistry chapter 8
2) Dujardin, A., Retting of Flax. Flax Development Committee, Belfast, Ireland (1948).
3) …..