Ancient records describe the use of hemp in China in 2800 BC It is bast fiber that is soft and durable that comes from the plant CANNABIS SATIVA an annual of family MORACEAE Now is cultivated in almost every European country and in Asia ID: 389873
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HEMP
Ancient records describe the use of hemp in China in 2800 B.C.
It is bast fiber that is soft and durable that comes from the plant CANNABIS SATIVA, an annual of family MORACEAE
Now is cultivated in almost every European country and in Asia.Slide2
Hemp
fibre
hemp reach a height of more than 10 feet. Due to its astonishing adoptability to altitude, it can reach to a height of nearly 8000 feet. hemp is a dioecious plant i.e. male and female flowers are born on a separate plant. Male plants are plucked 2-3 weeks before female plant. The male plant is shorter and thinner while Female plant is strong. male plant retted in 10 days while female plant retted in 3 weeks. In dew retting like flex retting, hemp stems are left to lie in the fields to allow humidity and heat to stimulate the growth of micro-organism. Fibres produced by dew retting are of medium length and dark in colour because moulds attach both pectin and cellulose. for water retting rivers or tanks are used; upper most hemp should be submerged 4 inches below the water surface and lower most should be 20 inches below the water surface. After 4 days fibre strands begin to separate from woody portion. Retting process continue and completes when fibre show white colour. It takes about 7-9 days. After washing in the same tank, fibres are dried and stored. Slide3
Macro structure
Hemp fibre is light in colour and has a high Luster like flex.
Under the microscope its longitudinal view shows frequent joins and fractures. Its diameter appears uneven and shows attachment of fregmentry tissues. The lumen is broad. The cross-sectional cells have round edges and not so sharp and polygonal as those of jute.
Hemp is not entirely pure cellulose; it appear to be mixture of cellulose and ligno-cellulose.Slide4
Structure
Strands of hemp fiber may be 2m.
The individual cells are 13-26 mm long.
The central canal or lumen is broader than that of flax, the ends of the cells are blunt. Slide5
Properties
Hemp fineness is less than that of linen, but its tensile strength is appreciably greater.
Hemp is more hygroscopic than cotton due to its structure.
Hydrochloric acid and potassium hydroxide produce a brown colour while ammonia produce a violet colour. Its sp.gravity is 1.48-1.5.
Tanacity is 48 gram/tex.
M.R is 12%Slide6
Uses
Hemp seeds contain all the essential amino acids and essential fatty acids necessary to maintain healthy human life. The seeds can be eaten raw, ground into a meal, sprouted, made into hemp milk. Prepared as tea, and used in baking. The fresh leaves can also be eaten in salads. Products include cereals, and nut butters.
Hemp can be cottonized but do not spin easily alone, use ful yarns when mixed with cotton.