SISAL

                                   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).

These fibres sometimes appear saw-edged and have
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.      

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.

Ramie

                                     RAMIE

Egyptian mummies of the pre-dynastic period (5000-3300 n.c.) were wrapped in fabric that has been identified as the bast fibre we now call ramie or China grass.

Botanical Information:-

This fibre comes from plants Boehmeria nivea or Boehmeria tenacissema.

                     

                                                  Ramie

Production and Processing:-

The ramie is a perennial, sending  up many stalks to a height of 1.2-2m (4-6ft). The plants are hardly and grow well in warm climates. They are harvested when the lower stalks turn yellow and the new stalks are beginning to make their appearance.

Decortication:-

The ramie fibers are removed from the stalks by the process of decortications. This is usually out by hand. The process consist in peeling or beating the bark and bast material from the stalks soon after harvesting. The fibers are freed by soaking the bar in water and scraping with knives made from shells, bronze or iron.

The long strands of ramie fibre are then dried and bleached in the sun.

The decortication process varies in detail in different regions. Sometimes the stalks are beaten against rocks before being peeled; the bark is battered with wooden .mallets to free the fibre from adhering woody matter. In Indonesia the" stalks are scraped in such a way as to leave the bast fibres clinging to the woody cores. These are then washed and the fibres are peeled away in the form of long ribbon-like strands.

Degumming:-

Before the ramie fiber can be spun, they must be released from the ribbons or strands in which they are held together by natural gum.

There are many degumming processes in use in different parts of the world. Where fiber production is carried out simply and by hand, the gums are removed by repeated soaking and scraping.

Soda or lime be used if these are available.

Commercial degumming is usually carried out by treating the fibers with caustic soda solution ( less then 1% ) for as long as four hours. The fibers are then treated with bleaching powder, followed by immersion in a bath of dilute acid. The bleaching and acid steeping are repeated until all the gum has been removed. Then the fiber is washed, oiled and dried.

Dyeing:-

Ramie can be dyed with all the classes of dyestuffs used for cotton, including direct, sulphur, basic, azoic and vat dyes. The techniques used are similar and the results are good. Dyeing is level and the fastness to light and washing is comparable with that of the same dyestuffs on cotton.

Structure and Properties:-

Ramie fibre is white and lustrous. Ramie yarns may be as strong as flax line yarns. The fibre is durable but lacks elasticity.

Ramie absorbs water readily. Fabrics made from it will launder easily and dry quickly. They can be dyed readily.

Ramie yarn tends to have a hairy feel, due to the stiffness and coarseness of the fibres, which reduces their cohesion.

The cells of ramie fibre often  45cm (18 in) more than 150 cm (59) long. They are smooth and cylindrical, with thick walls. The surface of the cell is marked by little ridges.

The lumen narrows and disappears towards the ends of the ramie cell, which tapers to a rounded point.

                      

       Ramie

Denier of rami fiber is 4.6-6.4. They are hexagonal and oval in shape.

Physical Properties:-

Specific Gravity    1.51-1.55

Tenacity                6.1g/dtex

Extension               3.8%

Chemical Properties:-

Cellulose                   68.6%

Pectin                         1.9%

Water Soluble         5.5%

Others                        16.4%

Ramie in Use:-

1-    Ramie is made into many types of industrial fabrics, such as canvas and packing materials.

2-    It is an increasing use in upholstery and furnishing and in cloth.

3-    Ramie yarns are used for fishing nets and sewing threads.

4-    The lack of cohesion between ramie fibers and the consequent hairiness of ramie yarn makes it difficult to weave ramie into a smooth fabric. Much of luster lost when it is made into cloth.

This draw back is overcome by mercerization process similar to that used for cotton.

5-    Ramie yarns are maintained under tension and treated with caustic soda. This brings about chemical and physical changes similar to those that take place in cotton.

Kenaf

                                       KENAF

Kenaf is one of the allied fibres of jute and shows similar characteristics.

In Africa kenaf has long been used as a source of fiber for making cordage and coarse fabrics.

Most of the world’s Kenaf is grown in India, Bangladesh and Thailand.

Botanical Information:-

The botanical name of Kenaf plant is Hibiscus.

                

                                    Kenaf                                                              

Production and Processing:-

The kenaf plant is an annual, with 12mm (1/2 in) diameter stalks that reach 3m (10 ft) in height. It grows well in the hot damp climate tropical countries.

The fibres in kenaf is found in the bast (bark) and core (wood). The bast constitute of 40 % of the plant.

 The methods used for harvesting and processing kenaf are similar to those used for jute. The stalks are retted and then beaten to free the fibre from unwanted material.

Structure and Properties:-

Kenaf is a pale-coloured fibre which contains less non-cellulosic material than jute. It has the lustre which is characteristic of many bast fibres.

Kenaf has a breaking strength similar, to that of low-grade jute, and it is weakened only slightly when wet.

The cells of kenaf are short, reaching only 6mm (1/4 in) in length. They are cylindrical and the surface is striated and irregular. The lumen varies greatly in thickness at different points in the cell, sometimes disappearing altogether.

                     

                              Dried Kenaf Stems

Seen in cross-section, the cell of kenaf fibre is polygonal and has a thick wall. It is coated with a layer of lignin. The fibre ends are thick and blunt(means Lacking sharp edges or point).

KENAF in USE:-

1-  Most of the kenaf produced at present is used for making ropes and twines.

2-  For coarse fabrics it is used for making canvas and sacking.

3-   Some of the better quality fibre is made into carpet mater.