Physical Characteristics of Jute Fiber:
Fine Structure and Appearance:
Commercial jute varies from yellow to brown to dirty grey in color, and it has a natural silky luster. It consists of bundles of individual fibers held together by gummy materials, including the natural plastic lignin which plays an important role in the structure of all woody plants.
Jute usually feels coarse and rough to the touch, although the best qualities are smooth and soft. Retting destroys the cellular tissue that holds the bast bundles together but does not normally separate the individual cells one from another. Some of the fiber ends become detached from the strands, giving the jute its hairy, rough feel.
The individual cells of jute are about 2.6mm long, on average. The cell surface is smooth but disfigured here and there by nodes and cross markings. The fibers are coated with a layer of woody material.
Seen in cross section, the cell is polygonal, usually with five or six sides. It has thick walls and a broad lumen of oval cross section. By contrast with the regular lumen of flax that of jute is irregular. It becomes narrow in places quite suddenly. Towards the ends of the cell which are tapered the lumen widens the cell walls become correspondingly thin. Jute contains about 20 per cent of lignin.
Tensile Strength:
Jute is not so strong as flax or hemp nor is it so durable. Individual fibers vary greatly in strength owing to the irregularities in the thickness of cell walls.
Elongation:
Jute fibers do not stretch to any appreciable extent. Jute has an elongation at break of about 1.7 per cent.
Elastic Properties:
Jute tends to be a stiff fiber owing to the part played by the material which cements the cells together.
Specific Gravity:
Specific gravity of jute is 1.5.
Effects of Moisture:
Jute is an unusually hygroscopic fiber. Its regain figure is 13.76%. it can be absorbed as much as 23% of water under humid conditions.
Effect of Age:
It kept dry; jute will last indefinitely although the high content of non-cellulosic matter tends to make it sensitive to chemical and photochemical attack. Moisture encourages deterioration of jute which loses strength with age.
Micro-organisms:
Jute is more resistant to rot than either grey cotton or flax. If lightly scoured, it can have an excellent resistance owing to the protective effect of the lignin.
