uses of plant fibres and starch

7/28/2019 Uses of Plant Fibres and Starch

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Plant fibres are very long sclerenchyma cells

and xylem tissue and are very tough.

They have great tensile strength cannot bebroken down easily.

They are very flexible.

High tensile strength and flexibility makes themvery useful.

Fibres usually have to be extracted from theplant first.



Paper is usually made from fibres from wood.

Wood is soaked in very strong alkalis such as

caustic soda.

Produce a pulp consisting of cellulose and

lignified cellulose fibres.

Thin layers of pulp pressed onto frames

where they dry to form paper.



Cotton is produced in the form of pure fibres,

packed around the seed.

Flax is produced by the action of decomposers

either by natural method or by using chemicals and

enzymes.

Extracted from the skin of the stem of plant.

The process of removal of fibres from the plant

stem is called retting.



Sustainability

Using resources in a way that minimizedamage to the environment.

That resources can be replaced.

It is better to use renewable sources

instead of non renewable sources.

Use plant based materials for fabrics,

ropes etc.



Synthetic fibres They are made from chemicals derived from

crude oil.

Crude oil is a non sustainable resource which

gets increasingly expensive.

they are exciting, relatively cheap , veryhardwearing (durable and tough) and did not

crease.

The main limitations are:they do not ‘breathe’ and

Do not soak up sweat

make us sweat profusely



Wood It is a composite material, made of lignified

cellulose fibres embedded in hemicellulosesand lignin.

They are very resistant to compression dueto the presence of cellulose micro fibrils.

So it can be used in supporting columns andbeams.

It also retain some flexibility and so doesn’t

tend to crack.Because of its flexibility we can hammer a

nail or cut into small pieces withoutchanging the strength.



Uses of wood

It is used to make furniture and to build

houses.

It is good insulator.

It also locks up carbon dioxide.



Uses of starch1.Main carbohydrate of nutritional

importance in the human diet.

2.Used as a thickener in processed

food, and in the manufacture of paper,biodegradable plastics and adhesive.

3.When cooked starch granules swell

to form gels that are used in food andnonfood industries.

4.Dried and cross linked starch is used

in nappies as it is a good absorbent



Oil based plastics Plastics which are made from petrochemicals are

called oil based plastics.

Petro chemicals are non renewable resources.

These plastics cannot be broken down by decomposers and are non- biodegradable.

These may lead to pollution.

Examples of oil based plastics are polythene and

PVC



Bio plastics These are plastics based on biological polymers such as

starch and cellulose.

They are sustainable sources- the starch and cellulosecomes from maize, wheat and potatoes.

These are biodegradable- bacteria and fungi can breakdown this.

Different types of bioplastics:- Cellulose based plastic

Thermoplastic starch

Polylactic acid (PLA)

Poly-3-hydroxybutyrate (PHB)



Cellulose based plastics are usually madefrom wood pulp.

Example :- cellophane

Thermoplastic starch:-

widely used bioplastic.

Mainly from starch extracted from potatoesand maize, which is then mixed withcompounds such as gelatin.

It is smooth, shiny and easy to swallow anddigest readily.

mainly used to make capsules to contain

drugs.



Polylactic acid:- largely produced from maizeor sugar cane.

Used in the production of computer casings,mobile phones and drinking cups

Poly-3-hydroxybutyrate:- it is used in ropes, carparts.

Produced by certain bacteria processingglucose, corn starch or waste water.



Advantages :-Bio degradable

Less harm to the environment

A renewable resource

Disadvantages:-

More expensiveConflict between use of crops between

food and for bioplastics.

uses of plant fibres and starch

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