Hemp is derived from the plant known as Cannabis Sativa. It is believed to have originated in the southwest of the Caspian sea (Russia).It spread to India and China and later to Italy, Switzerland and France. The plant is robust and grows naturally, requiring little cultivation. The stalks may reach a height of 10 feet or more .The Male is cultivated purely for its fibre, in the case of Female the flowers are allowed to ripen so that the seeds are harvested. The cultivation of hemp is closely approximate that of Flax. When the lower leaves fall off and the stalk turns yellow, crop is harvested usually by hand.
Physical and chemical properties of Hemp fibre :
1. Length - 12” to 25”
2. Diameter - 22 microns
3. Colour - Grey or Yellowish Brown
4. Specific Gravity - 1.48 to 1.50
5. Strength - 7 to 9 gms/denier
6. Moisture Regain - 12%
7. Flexibility - Poor
1. Dilute acids at boiling/weak mineral acids - Hydrolyses & produce hydrocellulose
2. Action of Organic acids - Resistant
3. Action Of Oxidizing Agent - Produces Ox cellulose
4. Action Of Micro Organisms - Resistant
Uses:It is used as substitute material in spinning of Flax and Ramie. But normally used for rigging (ropes, chain) varieties like hump cord, rope, harness, strings and fishing nets.