HEMP FIBRE
◆It is grown in almost all the countries of Europe including the USSR and in many parts of Asia.
◆It is an annual plant which is robust, tough and grows naturally requiring httle cultivation.
◆Its stalks may reach a height more than 10 feet and can be grow at
height of around 8000 feet.
◆As compared to flax it takes more time to grow, needs higher summer temperatures and can be grown for several years in succession in the same soil.
Introduction
◆Hemp comes from the bark of the plant 'Cannabis satina'.◆It is grown in almost all the countries of Europe including the USSR and in many parts of Asia.
◆It is an annual plant which is robust, tough and grows naturally requiring httle cultivation.
◆Its stalks may reach a height more than 10 feet and can be grow at
height of around 8000 feet.
◆As compared to flax it takes more time to grow, needs higher summer temperatures and can be grown for several years in succession in the same soil.
#Stages of fibre production
(a) Cultivation:-
◆The sowing is done in mid-April, The field should have soft, rich and moist soil.◆The seeds should have appropriate density and should be fufly ripened.
◆Hemp is a dioeciqus plant i.e: to say the male and female flowers are borne on separate plants.
◆The male is cultivated purely for its fibre whereas in the case of female the flowers are allowed to ripen so that the seeds are harvested.
◆The cultivation of hemp closely approximate that of flax.
◆When the lower leaves fall off and the stalks turn yellow, crop is harvested usually by hand.
(b) Harvesting
◆Harvesting is done at right moment neither too early nor too late.◆Early harvesting results in fewer, weaker and less glossy fibres whereas delayed harvesting results in woody, harsh and less lustrous fibres.
◆It usually takes place in August or September.
◆To get good quality fibre male plants are plucked 2-3 weeks before female plants.
◆The female plant is strong whereas male plant is shorter and thinner in stalk
(c) Retting:-
◆Hemp is retted in water tanks in a manner similar to flax after which the stalks are dried.◆The fibres are then separated either manually or mechanically by passing through fluted rollers which crush the woody tissues.
◆At this state the hemp is softened by beating with a softwood mallet on a flat stone or a hard floor.
◆Finally the fibres which tend to stick together are separated by combing.
◆The male plant can be retted in 10 daye whereas female plant being stronger needs 3 weeks.
Properties
◆Under microscope it is seen to consist of cell elements It is uneven in diameter.
◆Longitudinally fibre shows joints and fractures (cracks) on the surface.
◆In the cross-seetion, it is seen to be polygonal in shape with a pronounced lumen in the centre.
◆The fibre ends are thick walled and blunt.
Properties:-
(i) Microscopic appearance:-◆Under microscope it is seen to consist of cell elements It is uneven in diameter.
◆Longitudinally fibre shows joints and fractures (cracks) on the surface.
◆In the cross-seetion, it is seen to be polygonal in shape with a pronounced lumen in the centre.
◆The fibre ends are thick walled and blunt.
(ii) Length and diameter:-
The length varies between 0.5-1" and diameter is in range or 16-50microns.
The length varies between 0.5-1" and diameter is in range or 16-50microns.
(ii) Colour:-
It is pearl grey, yellowish or greenish to brown in colour.
It is pearl grey, yellowish or greenish to brown in colour.
(iii) Lustre:-
It has high lustre equal to that of linen.
It has high lustre equal to that of linen.
(v) Moisture regain: More hygroscopic than cotton. Its moisture regain is 12%
(vi) Specific gravity: 1.48-1.50.
(vi)Composition:-
77.8% cellulose, 9.3% inter-cellular matter and pectin bodies, 0.5% fats & waxes and 3.48% aqueous extract
77.8% cellulose, 9.3% inter-cellular matter and pectin bodies, 0.5% fats & waxes and 3.48% aqueous extract
(vii) Tensile strength:-
Greater than linen but it is coarser
Greater than linen but it is coarser
#Uses
Hemp is primarily used in making ropes and twines and is woven into fabrics for sack cloth and canvas.
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