SISAL
This is a leaf-fibre
that comes from the plant Agave sisalana, which is
indigenous to Central America.
It derives its name from the Yucatan port of
Sisal on the Gulf of Mexico.
The sisal
plant is now cultivated widely in East Africa, Mexico, Haiti, Brazil and in
other regions of South America. The world output (1978) is in the region of
550,000 tonnes.
Baled
Brazilian sisal fiber
Sisal
Production
and Processing:-
Sisal plants send up huge leaves
almost from ground level. The leaves are firm and fleshy, and form a rosette (a
design or object resembling a rose) on a short trunk (the main woody stem of a
tree).
After six or seven years of growth, the
sisal plant sends out a flower stalk that rises to some 6m (20 ft). When it has
flowered, the plant produces tiny buds which develop into small plants. These
fall to the ground and take root, and the parent plant dies.
Leaves are harvested when the plants
are 2 1/2 to 4 years old and at intervals until the plant eventually die.
A good plant may yield 400 leaves
during its lifetime, and each leaf may contain up to 1,000 fibres. The outer
mature leaves are cut away and treated in machines which scrapie the pulpy
material from the fibres. After washing, the fibre is dried and bleached in the
sun, or oven-dried.
Dyeing:-
Sisal has a good affinity for direct
cotton and acid dyestuffs, which provide attractive shades of good light
fastness.
Direct dyestuffs are used in the same
way as in the dyeing of cotton. Acid dyes are applied from a neutral or acid
dyebath.
Basic dyes are commonly used for
dyeing sisal which is used in ropes. They have poor light fastness and are less
satisfactory than direct or acid dyes when the sisal is used for matting.
Structure
and Properties:-
Strands of
commercial sisal are 60 - 120cm (2-4 ft) in length. They are strong and consist
of many individual fibres held together by natural gums. If processing has been
carried out carefully, the sisal is creamy-white in colour.
Sisal fibre
tends to be stiff and rather inflexible. It absorbs moisture readily and is
weakened by being steeped for long periods in salt water.
There are a
number of different types of cell in a typical specimen
of sisal. The 'normal' fibre cells are straight and stiff; they are
cylindrical and often striated. The average length is about 2.5mm
(l/10th in).
of sisal. The 'normal' fibre cells are straight and stiff; they are
cylindrical and often striated. The average length is about 2.5mm
(l/10th in).
These fibres
sometimes appear saw-edged and have
tapering ends.
tapering ends.
The lumen varies in thickness and definition;
the cell
walls arc thick where the lumen is thin and vice versa. The lumen is
often packed with tiny granules.
walls arc thick where the lumen is thin and vice versa. The lumen is
often packed with tiny granules.
Sisal also
contains broader fibres with a characteristic lattice pattern and with small
pore-markings. Some cells are cushion-shaped and others are short and
rectangular. Here and there, small spiral-shaped bodies can be seen, like
little springs.
Sisal
contains about 6 per cent of lignin (based on dry material).
Sisal
PROPERTIES
Physical
Properties:-
Denier 9-406 Tenacity 3.8g/dtex
Moisture Regain 11% Extension 1.9%
Length 40-100mm
Chemical Properties:-
Cellulose 65.8%
Pectin 0.8
Fat and Waxes 0.3%
Water Soluble 1.2
Sisal in
Use:-
1-
Sisal is one
of the most valuable of all cordage fibres.
2-
It is too
stiff to be used satisfactorily for certain purposes, such as power transmission,
in which it has to run through pulleys or over wheels
3-
Sisal is now
widely used for marine ropes and hawsers particularly in under-developed areas.
4-
Sisal is
used extensively for making baler and binder twine, and for sacks, paper
filters and other industrial uses.
5-
The high
strength, lustre and good colour of sisal have made it into an attractive fibre
for certain textile uses.
6-
It is made into matting and rugs.
7-
Its ability to take up direct cotton and acid
dye-stuffs has made it a popular fibre for ladies' hats.
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