Review

Indian Hemp

Journal of Textile and Clothing Science

ISSN: 2581-561X (Online)

http://www.jtcsonline.com

 

Review

INDIAN HEMP

Tejas Nagve

D.K.T.E. Society’s Textile and Engineering Institute, Ichalkaranji-416115 (MS) India

Mithilesh Bhagat

D.K.T.E. Society’s Textile and Engineering Institute, Ichalkaranji-416115 (MS) India

Ashish Hulle

D.K.T.E. Society’s Textile and Engineering Institute, Ichalkaranji-416115 (MS) India

 

ARTICLE INFO.

 

ABSTRACT

Article history:​​ 

Received:10/06/2019

Received in revised form:24/07/2019​​ 

Accepted:31/08/2019

 

Indian hemp is natural bast fibre. ​​ Indian hemp plant belongs to Crotalaria Juneau species. It is one of the under exploited fibre yielding plant. The fibres are present at the outer layer of the bast. Indian hemp fibres can be extracted by retting, enzymatic extraction and chemical extraction methods. Indian hemp fibres are cellulosic and multicellular in nature. Fibres are long and strong enough that they can used in manufacturing of ropes. Fibres are having lower density than cotton. Fibres are having good affinity toward moisture. Not only the fibre but entire Indian hemp plant is very useful. Harvesting of plant, extraction, properties and applications of Indian hemp fibres have been discussed in this paper.

Keywords:​​ Hemp, Extraction, Morphology, Properties, Applications

 

Introduction

There are still many natural fibres which have not been utilized to their full potential. It is because of lack of information about the natural fibres. From the plant kingdom “Crotalaria Juneau” is the species which is the source of strong natural fibre. It is also called as “Indian hemp”. Crotalaria Juncea has many uses; one of them is for getting fibres. It is widely grown in tropical and subtropical regions as a source of green manure, fodder and lignified fibre obtained from its stem. Plant servers a nitrogen fixation agent and​​ hence it is used as manure [1]. Crotalaria Juncea plant is shown in figure 1.

Figure​​ 1​​ Figure 1 Crotalaria Juncea [2]

Crotalaria Juncea is a shrubby, herbaceous legume. It grows up to a height of 1-4 m. It is a​​ multi-branched plant. The stems are up to 2 cm thick. It has many ascending branches. The leaf is simple 2.5-10.5 cm long and 6-20 mm broad. It is strongly tap rooted. There is spiral arrangement of leaves along the stem, hairy simple, oblong-lanceolate, or elliptical in shape. The inflorescence is a terminal open raceme, up to 25 cm long, bearing showy, deep yellow flowers. The fruit is cylindrical, many seeded hairy pod. It becomes light brown when mature, about 3-6 cm long with 1-2 cm in diameter [1].

Indian hemp

Indian hemp is one of the fibres containing plant. It is mostly found in India and Pakistan. It is cultivated in the winter season. Mostly in December and January. It is cultivated as a protective boundary of the field. Its height is about 8 to 10 feet. It has fibres in its bast. The measure of fiber is too high following a month and a half of planting. Indian hemp fibres are useful for making fishing nets, paper, and cordage. It has same properties as like the jute and other bast fibres. But it is not more popular as like the jute. After the extraction of fibres the bast are used as fuel [3].​​ 

Extraction Methods

Harvesting and Threshing

It is harvested by the manual method after the proper maturation of the bast and the seeds. In some of the area it is harvested during the flowering period. It is harvested in the month of September to October as the quality is concerned. The bast are cut closer to the field and left as it is in the field to absorb the atmospheric moisture for some day to reduce the retting process time. Before the retting all the leaves are removed manually and the bundles of bast are prepared. These bundles are then put into the water for the retting. Before putting it in to the water, all the mature​​ seeds are required to be removed properly for next cultivation [4].

Fibre Extraction

Fibres​​ form the bast are extracted by retting process. Retting processes like water retting, enzyme retting, chemical retting, and mechanical retting may be followed for the extraction. To accelerate the extraction process bast bundles are crushed before retting. After the retting bast bundles are taken out. Then every bast is taken outside the bundle and its surface is peeled out to obtain fibres.​​ 

Figure​​ 2​​ Indian Hemp Fibre Extraction [5]

The fibres​​ are separated by the applying simple downward force. It is done for individual bast. After removal, fibres are washed in water and sun-dried [3]. Washing releases natural binding elements which bind​​ the finer components of fibre together. Fibre extraction process is shown in fibre 2.

Water Retting​​ 

There are microbes in the water which help in the extraction of fibres. Bacteria softens the bond between fibre and nonfibrous material which facilitates manual separation of fibres by hand. In water retting the bast bundles are kept into the water as for example in river, ponds, or flowing water streams for 18 to 21 days. Stones are put on each bundle for the proper immersion of the bundles into the water. Water penetrates inside the bast. Which result in to loosening of fibre from nonfibrous materials. The process is not controllable. The color variation may also occur which degrades aesthetic look of fibre.

Chemical retting

Chemical retting is the fastest method of fibre extraction. In this method bast is treated with acids and alkalis such as sodium hydroxide, sulfuric acid etc. in with predetermined process variables. ​​ The method can produce fibres with smooth surface but adversely affects the tensile strength [5,6].

Enzymatic Retting

In enzymatic retting the extraction is done by using pectic enzymes produced by bacteria. During the process the bacteria multiplies in number and produce pectinases. Pectinases dissolve the pectin and this releases the bast fibres from surrounding cortex. Enzymes such as pectinase, xylanase are used in enzyme retting. The process needs to be carried out under controlled conditions. This process is faster but costlier. The process usually requires 12-24 hours [7, 8].

Morphological Structure of Indian Hemp

Longitudinal as well as cross sectional view of Indian hemp fibre is exhibited in figure 3 and figure 4 respectively.​​