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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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