RDL730 TECHNOLOGY ALTERNATIVES FOR RURAL DEVLOPMENT

UNCONVENTIONAL FIBRE PLANTS: A SOURCE OF SUSTAINAB LELIVELIHOOD

April 29

2011 Submitted To:- -Dr.V.R.CHARIAR Dept.Of RURAL DEVLOPMENT IIT DELHI

Submitted By:-

Rajendra Singh

(2010TTE3680)

Pradeep Singh

Tanwar

(2010TTE3666)

Dept.Of Textile

Technology

Abstract: “Anna, Bastra and Basasthan”–are not only slogans but are prime requirement

since ancient times. The basic requirements changed with the evolution of

civilization. Natural fibres have wide scope of application in textile field,

particularly due to recent tilt towards more friendly textiles. Amongst

conventionally used fibres like cotton, wool, jute and silk there are many other

fibres produced in India which fall into the category of unconventional fibres like

ramie, pineapple, bananas, sisal etc. These unconventional fibres are commonly

used for preparation of a wide variety of products and in many forms. Application

of these fibers include filler or reinforcement materials, insulation or used as

structural elements and disposable or durable products such as yarns and textiles;

ropes, twines and nets; non-woven fabrics, tissues; paper and board products;

packaging; building and construction materials, fibre boards, geotextiles;

composites and automotive parts. The return to nature to meet our clothing, food

and medicinal need is one option that is required if we want to achieve sustainable

living. We must also return to traditional methods of production- back to chemical

free and organic production methods.

Key words: Unconventional fibers, Natural fibers, Sustainable living.

Introduction

During the early days of his existence, man was dependent upon animal skins and

furs to keep him warm. A sheep skin wrapped carelessly round the body may be

better than nothing for keeping out the cold.

Inevitably, man began to look around for something that would keep him warm

more elegantly and more comfortably than an evil-smelling hide. At some point in

history, he found that the long thin fibres produced by plants and animals could be

twisted together to form a thread. These threads then interlaced into woven fabric

to provide a flexible, warm and supremely comfortable material such as he had

never known before.

The fibres used in modern textile manufacture can be classified into two main

groups:

(a) natural and (b) man-made fibres.

.

Natural fibres can be subdivided into three main classes, according to the nature of

their source i.e. vegetable fibres, animal fibre and mineral fibres. India has a rich

heritage of natural plant material due to wide range of climatic variations.

Vegetable fibres of plant origin are used in variety of textile and industrial

products. The vegetable or plant based fibres are cellulosic in nature and are

classified into hard and soft fibre categories according to their availability in a

particular part of the plant and also based on the stiffness associated with it in the

raw state

Most soft fibres come from the bast portion of the plant, also called the phloem, the

bast lies directly under the outer bark or skin. Here the transport of the products of

photosynthesis and the development of stabilizing structures take place. Through

the process of retting, the bast is removed from the stems. Hemp, Flax, Jute and

Ramie are soft fibres.

Hard fibres are comprised not only of the phloem but also partly of the hardened

wood core of the plant, the Xylem. The hardness in the the plant's fibres is caused

by the deposit of lignin in the cell walls. Hard fibres generally come from the

leaves of monocot (single seed-leaf) species, for example sisal, banana and diverse

palms.

Extraction of fibres 1. Retting: This process employes the action of bacteria and moisture on plants to

dissolve or rot away much of the cellular tissues and gummy substances

surrounding bast-fibre bundles, thus facilitating separation of the fibre from the

stem. Basic methods include water retting and dew retting.

In water retting, the most widely practiced method; bundles of stalks are

submerged in water. The water, penetrating to the central stalk portion, swells the

inner cells, bursting the outermost layer, thus increasing absorption of both

moisture and decay-producing bacteria. Retting time must be carefully judged;

under-retting makes fiber separation difficult, and over-retting weakens the fibre.

In double retting, a gentle process producing excellent fibre, the stalks are removed

from the water before retting is completed, dried for several months, and then

retted again

Natural water retting employs stagnant or slow-moving waters,

such as ponds, and slow streams and rivers. The stalk bundles

are weighted down, usually with stones or wood, for about 8 to

14 days, depending upon water temperature and mineral content.

Dew retting, which is common in areas having limited water

resources, is most effective in climates with heavy nighttime

dews and warm daytime temperatures. In this procedure, the

harvested plant stalks are spread evenly in grassy fields, where

the combined action of bacteria, sun, air, and dew produces

fermentation, dissolving much of the stem material surrounding

the fibre bundles. Within two to three weeks, depending upon

climatic conditions, the fibre can beseparated. Dew-retted fibre

is generally darker in colour and of poorer quality than water-

retted fibre.

Tank retting, an increasingly important method, allows greater

control and produces more uniform quality. The process, usually

employing concrete vats, requires about four to six days and is

feasible in any season. In the first six to eight hours, called the

leaching period, much of the dirt and colouring matter is

removed by the water, which is usually changed to assure clean

fibre. Waste retting water, which requires treatment to reduce

harmful toxic elements before its release, is rich in chemicals

and is sometimes used as liquid fertilizer.

The retted stalks, called straw, are dried in open air or by

mechanical means and are frequently stored for a short period to

allow curing to occur, facilitating fibre removal. Final separation

of the fibre is accomplished by a breaking process in which the

brittle woody portion of the straw is broken, either by hand or by

passing through rollers, followed by the scutching operation,

which removes the broken woody pieces (shives) by beating or

scraping. Some machines combine breaking and scutching

operations. Waste material from the first scutching, consisting of

shives and short fibres, is usually treated a second time. The

short fibre (tow) thus obtained are frequently used in paper

manufacture, and the shives may serve as fuel to heat the retting

water or may be made into wallboard.

2. Decortication: Decorticator is used for the extraction of

fibres from some hard leaves such as sisal and murva. There are

three types of decorticator available in the market i.e. disal

based, patrol based and electrical decorticator.

Industrial applications of fibre crops Fibres are commonly applied in a wide variety of products and

in many forms. Applications include as filler, or reinforcement;

insulation or used as structural elements, and disposable or

durable products such as:

1. Apparels and furnishings

The fiber is one of the most valuable parts of the unconventional

fibre plant. Flax fibers are amongst the oldest fiber crops in the

world. The use of flax fibre in the manufacturing of cloth in

northern Europe dates back to Neolithic times. Flax fiber is

extracted from the bast or skin of the stem of flax plant. Flax

fiber is soft, lustrous and flexible. Characteristics of hemp fibre

are its superior strength and durability, resistance to ultraviolet

light and mold, comfort and good absorbency (8%). As these

bast and leaf fibers can not be used in 100% products due to

their lack of pliability, so these are commonly blended with

fibres such as linen, cotton or silk, for apparel and furnishings.

2. Ropes, twines, fishing nets

The competitive price and performance of synthetic fibres has

led to a severe decrease in the use of natural fibres in the

manufacturing of ropes and binder twines. In many regional

markets synthetic fibres have totally displaced natural fibre

products. However, in some applications the biodegradability of

natural fibre products has substantial advantages for the

environment. For example in horticulture, or in shipping and

fisheries, where synthetic fishing nets and hawsers, are widely

used because of their strength, are causing severe damage to

wild life due to their persistence. Therefore sisal or agave (that

yields a stifffiber) may be used in making rope. Beside this

hemp, flax and coir fibres are also used for making rope and

twines although their cost is high but are ecofriendly.

3. Paper and boards

The paper and pulp applications of non-wood fibres in wood-

free

pulps, as compared to wood based products have a negative

environmental image. This is mainly due to partial application of

effluent

treatment and chemical recovery systems in relatively small

scale pulping

mills. Approximately 10 per cent of the world’s virgin pulp is

made from

non-wood pulp of which a large proportion is produced in China

from

wheat and rice straw, bagasse and bamboo. These papers are of

a higher

quality then tree papers so it has an expensive feel to it. Because

no acids

are needed to process the hemp into paper, hemp paper will not

yellow

soon after printing. It lasts thousands of years rather then a few

decades as for tree paper. It can be recycled many times over (7)

as opposed to 3 for tree paper. The best thing about hemp paper

and other paper manufactured from the unconventional fibre

plant is that we no longer need to cut down trees for pulp.

4. Non-woven fabrics

Non-woven fabrics manufactured by dry-laid needle

punching technology can be produced from most natural fibres.

Each fibre yields a characteristic fabric, depending on its length

and softness. For various applications, to enhance the coherence

in the non-woven mat, cross-linking chemicals are used, or the

fibres are blended with synthetic fibres, consolidated and

finished by subsequent calendering on hot rollers. Alternatively,

a wet laid process can be used. With this technology, high

pressure water jets are used to entangle the fibres and, similar to

paper making processes, the fibres form bonds at contact points

upon drying, resulting in a strong web structure.

Non-wovens are applied in various forms and products, such as:

tissues and hygienic products; filters; sorbents in diapers and

disposables; building industries as insulation mat, filling

material in mattresses, furniture; floor covering and carpets;

laminates and composites; horticultural substrate and

geotextiles.

5. Geotextiles

Hemp-based erosion control blanket Geotextiles are used in areas such as reinforcement for

embankments in order to prevent erosion in landscape

engineering structures. The natural biodegradation of the

lignocellulosic fibres can be considered to be an important

advantage in temporary civil engineering applications. However,

the functional life time of a geotextile should be sufficient,

under the applied conditions, and provide the required protection

against erosion, as long as the construction needs to be

stabilised. Production of hemp erosion control mats is

continuing in both Europe and Canada. Given the reputation for

rot resistance of hemp canvas and rope, it seems probable that

ground matting is a legitimate use. Moreover, the ability to last

outdoors for many years is frequently undesirable in geotextiles.

6. Horticultural production materials

Artificial substrates, synthetic binder twines, plastic clips and

plant pots are extensively used in modern horticultural

production. For producers, the disposal of plastic inputs and

substrates for soil-less production, such as mineral wool is

increasingly becoming a problem, whilst mineral woolproducts

may also negatively affect human health. As an alternative, the

use of renewable growing media has been investigated with coir

pith, the residue from coir fibre production, being introduced as

a renewable substitute for artificial media, or peat moss. Other

fibrous materials and bark have also been considered for

conversion to ecologically sound alternatives in potting mixtures

and substrates with promising results. The production process of

these alternatives requires less energy whilst their disposal

presents no problem to the environment.

Biodegradable plant pots manufactured by natural fibres and

different binders provide an alternative to plastic plant pots.

However, substitution possibilities are limited mainly to the

relatively low price of plastic pots, in spite of the fact that

biodegradable plant pots result in a reduction in labour, as

replanting in nurseries becomes unnecessary as roots are able to

grow through the pot walls.

7. Building materials

New building in France being constructed entirely of hemp Building industries contribute to a large extent to resource

depletion, waste generation and energy consumption, while on

the other hand the built environment is vital to economic

development. Fibre crops could play a more prominent role in

building and construction applications, as fibre board material,

insulation materials, as well as reinforcement, or filler. In light-

weight concrete, bricks and loam building blocks, cellulosic

fibres have been known to provide good properties. In the

production of substitutes for asbestos cement, abaca fibres were

proven specifically suitable.

Application of fibres in the manufacturing of boards for building

is determined mainly by relative prices and can be feasible when

fibres can be produced with lower costs than wood chips. In

most cases, the amount of synthetic glue, or resin required for

binding the fibres to form strong board materials is higher than

in the case of wood fibres. This increases the production costs of

the board product, but also its ecological performance. Coatings,

paints and adhesives that are mainly based on petrochemical

products, are necessary to increase the durability of renewable

building inputs. In order to increase the environmental

performance of renewable building materials, varnishes, paints

and coatings based on plant oils should preferably be applied.

Similarly, natural resins derived from plants, such as lignin and

furans should be developed for production on commercial scale

and become available as binders for boards and as components

in protective coatings.

8. Composites

Concrete block made with hemp in France

Composite fibre products are not new. The first composite

material known was made in Egypt around 3,000 years ago

when clay was reinforced with straw to build walls. With the

advent of metals, the use of natural fibre for reinforcing

declined. The rise of composite materials began during the

1960s when glass fibres in combination with tough rigid resins

was produced on a large scale. The advantages of using plant

fibre include lower raw material price, caloric recycling or

saving of non-renewable resources. Natural fibres offer many

attractive technical and environmental qualities when used as

reinforcements in polymer composites. They provide high

specific strength and stiffness, processability and low raw

material and manufacturing energy costs to a range of

thermoplastic and thermosetting composite materials. In the last

couple of decades, natural fibre composites of thermoplastics

and thermosets have found their way into the European car

manufacturers for door panels, seat backs, headliners, package

trays, dashboards, and trunk/boot liners. These benefits mean

that the potential market for natural fibre reinforcement is very

large. The automotive industry, in particular, is keen to exploit

their cost, weight and environmental benefits in thermoplastic

injection moulded products.

It is recognised that, under optimum circumstances, natural

fibres could produce composites with specific strength matching

that of glass fibre-reinforced plastic and with specific stiffness

exceeding it.

Conclusion India is considered as one of the vanguards of environmental

protection. A country that is committed for the elimination of

environmentally harmful processes and over-exploitation of

non-renewable resources. The extent to which the use of natural

fibres results in environmental benefits, over synthetic fibres in

industrial applications partly depends on the possibilities for

substitution of the various fibres in the processing, the energy

requirement of the production process, the product performance

and the functional life time, including options for waste

disposal.

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