polymer science

POLYMER SCIENCE AND POLYMER SCIENCE AND TECHNOLOGYTECHNOLOGY

Engineering/Applied ChemistryEngineering/Applied Chemistry

CODE NO: 07CODE NO: 07

I B.TECHI B.TECH

MECHNICAL/CIVIL ENGINEERINGMECHNICAL/CIVIL ENGINEERING

Unit No: VUnit No: V

Nos. of slides: Nos. of slides:

Engineering/Applied ChemistryEngineering/Applied Chemistry

POLYMER SCIENCE POLYMER SCIENCE Term: 2008-09Term: 2008-09

Unit-V Power Point PresentationsUnit-V Power Point PresentationsText Books:Text Books: A text book of Engineering Chemistry A text book of Engineering Chemistry

by Jain & Jain, by Jain & Jain, Chemistry of Engineering Materials by Chemistry of Engineering Materials by

C.P. Murthy, C.V. Agarwal and A. C.P. Murthy, C.V. Agarwal and A. NaiduNaidu

INDEXINDEXUNIT-V PPTSUNIT-V PPTS

Srl. Module as per Lecture PPTSrl. Module as per Lecture PPTNo. Session Planner No. Slide No.No. Session Planner No. Slide No.--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1. L-1 L1-1 to L1-191. L-1 L1-1 to L1-192. L-2 L2-1 to L2-282. L-2 L2-1 to L2-283. L-3 L3-1 to L3-18 3. L-3 L3-1 to L3-18 4. L-4 L4-1 to L4-184. L-4 L4-1 to L4-185. L-5 L5-1 to L5-195. L-5 L5-1 to L5-196. L-6,7 L6,7-1 to L6,7-33 6. L-6,7 L6,7-1 to L6,7-33

Polymer is a macro molecule formed by Polymer is a macro molecule formed by the union of many small molecules.the union of many small molecules.

Depending upon the structure, a Depending upon the structure, a polymer may be linear or branched.polymer may be linear or branched.

Ex. – CH2 – CH2 – CH2--Si – O – Si –Ex. – CH2 – CH2 – CH2--Si – O – Si –Polyethylene | | Polyethylene | |

Linear CH2- Si – O – Si – Linear CH2- Si – O – Si – Branched silicon resin.Branched silicon resin.

Depending type of monomer, they Depending type of monomer, they may be homopolymer (made up of may be homopolymer (made up of same monomer) or same monomer) or

Co-polymer (made up of different Co-polymer (made up of different monomers)monomers)

POLYMERISATION:POLYMERISATION: It may be defined as the process of linking It may be defined as the process of linking

or joining together small molecules like or joining together small molecules like monomers to make large molecules.monomers to make large molecules.

Basically there are 3 types of Basically there are 3 types of polymerizations.polymerizations.

Additional polymerization or Chain Additional polymerization or Chain polymerizationpolymerization

Condensation polymerization or Step Condensation polymerization or Step polymerizationpolymerization

CopolymerizationCopolymerization

Additional polymerization or Additional polymerization or Chain polymerization:Chain polymerization:

This polymerization yields an exact This polymerization yields an exact multiple of basic monomeric molecules. multiple of basic monomeric molecules. This monomeric molecule contains one or This monomeric molecule contains one or more double bonds. more double bonds.

By intermolecular rearrangement of these By intermolecular rearrangement of these double bonds makes the molecule double bonds makes the molecule bifunctional. bifunctional.

In this polymerization process light, heat In this polymerization process light, heat and pressure or catalyst is used to and pressure or catalyst is used to breakdown the double covalent bonds of breakdown the double covalent bonds of monomers.monomers.

Condensation polymerization or Condensation polymerization or Step polymerizationStep polymerization

May be defined as “a reaction occurring between simple polar-May be defined as “a reaction occurring between simple polar-group-containing monomers with the formation of polymer and group-containing monomers with the formation of polymer and elimination of small molecules like water, HCl, etc.” For elimination of small molecules like water, HCl, etc.” For example, hexamethylene diamine and adipic acid condense to example, hexamethylene diamine and adipic acid condense to form a polymer, Nylon6:6.form a polymer, Nylon6:6.

Additional polymerization is a chain reaction converting of a Additional polymerization is a chain reaction converting of a sequence of three steps. Initiation, propagation and sequence of three steps. Initiation, propagation and termination.termination.

a. Initiation step is considered to involve two reactions. The a. Initiation step is considered to involve two reactions. The first is the production of free radicals, usually, by the first is the production of free radicals, usually, by the hemolytic dissociation of an initiator (or catalyst) to yield a pair hemolytic dissociation of an initiator (or catalyst) to yield a pair of radicals R’.of radicals R’.

I I 2R’ ………(1) 2R’ ………(1) (Initiator) (Free radicals)(Initiator) (Free radicals)

The second part of initiation under The second part of initiation under the addition of this radical to the just the addition of this radical to the just moment molecule (M) to produce the moment molecule (M) to produce the chain initiating species chain initiating species

R + M R + M M1 ……….(2) M1 ……….(2) Free radical monomer molecule Free radical monomer molecule Thus the polymerization of monomer CH2 = CHY taken in the Thus the polymerization of monomer CH2 = CHY taken in the

form.form. HH R + CH2 = CHY R + CH2 = CHY R- CH2 – C R- CH2 – C RR

b. Propagation step:b. Propagation step:

Consists of the growth of M1 by Consists of the growth of M1 by successive additions of large successive additions of large numbers of monomer molecules numbers of monomer molecules according to equation.according to equation.

M1+ M M1+ M M2 M2 M2+ M M2+ M M3 M3 M3+ M M3+ M M4 or in general terms M4 or in general terms

Mn + M Mn + M Mn + 1 Mn + 1

c. Termination step:c. Termination step:

At some time, the propagation At some time, the propagation polymer chain steps growing and polymer chain steps growing and terminates.terminates.

H H H H H H H H - CH2 – C + C – CH2 - CH2 – C + C – CH2 - CH2 – C – C – CH2 - CH2 – C – C – CH2 Y Y Y Y Y Y Y Y

Disproportion in which a hydrogen Disproportion in which a hydrogen atom of one radical center is atom of one radical center is transferred to another radical center. transferred to another radical center. This results in the formations of two This results in the formations of two polymer molecules, are saturated and polymer molecules, are saturated and one unsaturated e.g. one unsaturated e.g.

H H H H H H H H H H CH2 – C + C – CH2 CH2 – C + C – CH2 CH2 – CH + C = C – CH2 – CH + C = C – Y Y Y Y Y Y Y Y

The two different modes of terminations can The two different modes of terminations can be represented in general terms by:be represented in general terms by:

M*n + M*m M*n + M*m M*n+m M*n+m (Coupling) (Coupling) M*n + Mm* M*n + Mm* Mn + Mm Mn + Mm

(Disproportionation)(Disproportionation)

Co-polymerization:Co-polymerization:

Polymerization involving two Polymerization involving two different monomers.different monomers.

Ex. Polymerization of butadiene and Ex. Polymerization of butadiene and styrene to gave Buna –S. styrene to gave Buna –S.

CH2 = CH – CH = CH2 + nx CH2 = CH –Ph CH2 = CH – CH = CH2 + nx CH2 = CH –Ph -C -CH = CH –CH - -CH2 –CH - -C -CH = CH –CH - -CH2 –CH -

1,3-butadiene (75%) Styrene(25%)1,3-butadiene (75%) Styrene(25%)

compounding of compounding of plasticsplastics

Compounding of the plastics may be Compounding of the plastics may be defined as the mixing of different materials defined as the mixing of different materials like plasticizers, fillers of extenders, like plasticizers, fillers of extenders, lubricants, dies and pigments to the lubricants, dies and pigments to the thermoplastic and thermosetting plastics to thermoplastic and thermosetting plastics to increase their useful properties like increase their useful properties like strength, toughness, etc. strength, toughness, etc.

Resins have plasticity or binding property, Resins have plasticity or binding property, but need other ingredients to be mixed with but need other ingredients to be mixed with them for fabrication into useful shapes.them for fabrication into useful shapes.

Compounding of plastics:Compounding of plastics:

Many plastics are virtually useless along but are Many plastics are virtually useless along but are converted into highly serviceable products by combining them with converted into highly serviceable products by combining them with a variety of additives, stabilizers etc., by the compounding a variety of additives, stabilizers etc., by the compounding process. The exact formulation will depend upon the specific process. The exact formulation will depend upon the specific application requirement. The different additives impart different application requirement. The different additives impart different physical properties which are used to improve the performance of physical properties which are used to improve the performance of the plastic materials. Additives are widely used for thermoplastics, the plastic materials. Additives are widely used for thermoplastics, thermo sets and elastomers like phenolics or amino resins are thermo sets and elastomers like phenolics or amino resins are useless alone but by the addition of fillers, resins etc., they give a useless alone but by the addition of fillers, resins etc., they give a reversible products. Some of the compounding materials are reversible products. Some of the compounding materials are stabilizers, plasticizers, fillers, colourants or pigments, lubricants stabilizers, plasticizers, fillers, colourants or pigments, lubricants and accelerators.and accelerators.

What is Plastic?What is Plastic?

Plastics are the materials that show the Plastics are the materials that show the property of plasticity and can be moulded into any desired property of plasticity and can be moulded into any desired shape and dimensions by the application of heat and shape and dimensions by the application of heat and pressure. Plastics having variety of properties are in use pressure. Plastics having variety of properties are in use in present applications. The properties are low thermal in present applications. The properties are low thermal and electrical conductivities, easy to fabricate, low specific and electrical conductivities, easy to fabricate, low specific gravity etc. The plastics can be fabricated for large gravity etc. The plastics can be fabricated for large number of colours and can be used for decorative number of colours and can be used for decorative purpose. Plastics can be used to produce complicated purpose. Plastics can be used to produce complicated shapes and accurate dimensions very cheaply by shapes and accurate dimensions very cheaply by moulding process. Plastics are generally used for making moulding process. Plastics are generally used for making automobile parts, goggle, telephones, electrical automobile parts, goggle, telephones, electrical instruments, optical instruments, household appliances instruments, optical instruments, household appliances etc. plastics having high wear resistance properties can etc. plastics having high wear resistance properties can be used for making gears, bearings etc. be used for making gears, bearings etc.

Merits of PlasticsMerits of Plastics

Plastics have good shock Plastics have good shock absorption capacity absorption capacity compared with steel.compared with steel.

Plastics have high Plastics have high abrasion resistance.abrasion resistance.

plastics are chemically plastics are chemically inert.inert.

Plastics have high Plastics have high corrosion resistance corrosion resistance compared to metals.compared to metals.

Mounding, machining, Mounding, machining, drilling etc. can be drilling etc. can be easily done on plastic easily done on plastic materials.materials.

Plastics are light in Plastics are light in weight having weight having specific gravity from specific gravity from 1 to 2, 4.1 to 2, 4.

Plastics can be made Plastics can be made according to the order according to the order like hard, soft, rigid, like hard, soft, rigid, tough, brittle, tough, brittle, malleable etc.malleable etc.

Fabrication of plastics into desired shape Fabrication of plastics into desired shape and size is cheap.and size is cheap.

Plastics are dimensionally stable.Plastics are dimensionally stable.

Plastics are don’t absorb water.Plastics are don’t absorb water.

Thermal coefficient of expansion of Thermal coefficient of expansion of plastic is low.plastic is low.

Excellent outer finish can be obtained on Excellent outer finish can be obtained on plastic products.plastic products.

Demerits of PlasticsDemerits of Plastics

Plastics are softPlastics are soft Plastics have poor ductility.Plastics have poor ductility. Resistance to heat is less.Resistance to heat is less. Cost of plastics is high.Cost of plastics is high. Plastics can deform under load.Plastics can deform under load.

plasticsplastics

Plastics are the materials that show the Plastics are the materials that show the property of plasticity and can be property of plasticity and can be

moulded into any desired shape and moulded into any desired shape and dimensions by the application of heat dimensions by the application of heat and pressure. Plastics having variety and pressure. Plastics having variety

of properties are in use in present of properties are in use in present applications. applications.

The properties are low thermal and electrical The properties are low thermal and electrical conductivities, easy to fabricate, low specific conductivities, easy to fabricate, low specific gravity etc. gravity etc.

The plastics can be fabricated for large number The plastics can be fabricated for large number of colours and can be used for decorative of colours and can be used for decorative purpose. purpose.

Plastics can be used to produce complicated Plastics can be used to produce complicated shapes and accurate dimensions very cheaply shapes and accurate dimensions very cheaply by moulding process. by moulding process.

Plastics are generally used for making Plastics are generally used for making automobile parts, goggle, telephones, electrical automobile parts, goggle, telephones, electrical instruments, optical instruments, household instruments, optical instruments, household appliances etc. appliances etc.

plastics having high wear resistance properties plastics having high wear resistance properties can be used for making gears, bearings etc. can be used for making gears, bearings etc.

Merits of PlasticsMerits of Plastics Plastics have good shock absorption capacity compared with Plastics have good shock absorption capacity compared with

steel.steel. Plastics have high abrasion resistance.Plastics have high abrasion resistance. plastics are chemically inert.plastics are chemically inert. Plastics have high corrosion resistance compared to metals.Plastics have high corrosion resistance compared to metals. Mounding, machining, drilling etc. can be easily done on Mounding, machining, drilling etc. can be easily done on

plastic materials.plastic materials. Plastics are light in weight having specific gravity from 1 to Plastics are light in weight having specific gravity from 1 to

2, 4.2, 4. Plastics can be made according to the order like hard, soft, Plastics can be made according to the order like hard, soft,

rigid, tough, brittle, malleable etc.rigid, tough, brittle, malleable etc. Fabrication of plastics into desired shape and size is cheap.Fabrication of plastics into desired shape and size is cheap. Plastics are dimensionally stable.Plastics are dimensionally stable. Plastics are don’t absorb water.Plastics are don’t absorb water. Thermal coefficient of expansion of plastic is low.Thermal coefficient of expansion of plastic is low. Excellent outer finish can be obtained on plastic products.Excellent outer finish can be obtained on plastic products.

Demerits of PlasticsDemerits of Plastics

Plastics are softPlastics are softPlastics have poor ductility.Plastics have poor ductility.Resistance to heat is less.Resistance to heat is less.Cost of plastics is high.Cost of plastics is high.Plastics can deform under load.Plastics can deform under load.

compounding of plastics:Compounding of the

plastics may be defined as the mixing of different materials like plasticizers, fillers of extenders, lubricants, dies and pigments to the thermoplastic and thermosetting plastics to increase their useful properties like strength, toughness, etc. Resins have plasticity or binding property, but need other ingredients to be mixed with them for fabrication into useful shapes.

Compounding of plastics: Many plastics are virtually useless along but are

converted into highly serviceable products by combining them with a variety of additives, stabilizers etc., by the compounding process.

The exact formulation will depend upon the specific application requirement.

The different additives impart different physical properties which are used to improve the performance of the plastic materials.

Additives are widely used for thermoplastics, thermo sets and elastomers like phenolics or amino resins are useless alone but by the addition of fillers, resins etc., they give a reversible products.

Some of the compounding materials are stabilizers, plasticizers, fillers, colorants or pigments, lubricants and accelerators.

Ingredients used in compounding of plastics

Plasticizers. Fillers or extenders. Dyes and pigments. Lubricants.

Plasticizers

Plasticizers are substances added to enhance the plasticity of the material and to reduce the cracking on the surface. Plasticizers are added to the plastics to increase flexibility and toughness. Plasticizers also increase the flow property of the plastics.

Example Dibutytyle oxalate, Castor oil and

Tricresyl phosphate

fillers or Extenders

Fillers are generally added to thermosetting plastics to increase elasticity and crack resistance. Fillers improve thermal stability, strength, non combustibility, water resistance, electrical insulation properties and external appearance.

Example wood flour, Asbestos, Mica, Cotton,

Carbon black, Graphite, Barium sulphate etc.

Dyes and pigments

These are added to impart the desired colour to the plastics and gives decorative

effect.

Lubricants

These are added to prevent the plastics from sticking to the moulds.

Example Oils, Waxes, Soaps etc. Thus the objective of

compounding is to improve the properties of the basic resin, such that the fabrication is made easy.

Fabrication of plastics:Many methods of fabricating plastics

into desired shaped articles are employed.

This production of plastics is known as fabrication of plastics.

The methods, usually depends upon the types of resins used i.e., whether thermosetting or thermoplastic.

Different fabrication techniques are described below.

Moulding of Plastics

Moulding of plastics comprises of forming an article to the desired shape by application of heat and pressure to the moulding compounds in a suitable mould and hardening the material in the mould. The method of moulding depends upon the type of resins used.

i) Compression moulding: This method is applied to both thermoplastic

and thermosetting resins. The predetermined quantity of plastic

ingredients in proper properties are filled between the two half –pieces of mould which are capable of being moved relative to each other heat and pressure are than applied according to specifications.

The containers filled with fluidized plastic. Two halves are closed very slowly.

Finally curing is done either by heating or cooling. After curing the moulded article is taken out by opening the mould parts.

Injection moulding: In this method, the moulding plastic

powder is fed into a heated cylinder from where it is injected at a controlled rate into the tightly locked mould by means of a screw arrangement or by a piston plunger.

The mould is kept cold to allow the hot plastic to cure and become rigid.

When the materials have been cured sufficiently, half of the mould is opened to allow the injection of the finished article without any deformation, etc.

Heating is done by oil or electricity.

Transfer moulding:

In this method, the principle is like injection moulding. The moulding powder is heated in a chamber to become plastic.

Later it is injected into a mould by plunger working at high pressure through orifice.

Due to this heat is developed and the plastic melts, takes the shape of the mould.

Extrusion moulding: This process is useful in the preparation of

continuous wires with uniform cross section. The heated plastic is pushed into the die with the

help of screw conveyor. In the die, the plastic gets cooled due to the exposure to atmosphere and by artificial air jets.

Extrusion moulding is used mainly for continuous moulding of thermoplastic materials into articles of uniform cross section like tubes, rods, strips, insulated electric cables.

The thermoplastic ingredients are heated to plastic condition and then pushed by means of a screw conveyor into a die, having the required outer shape of the article to the manufactured.

Here the plastic mass gets cooled, due to the atmospheric exposure (or artificially by air jets).

A long conveyor carries away continuously the cooled product.

PolyethylenePolyethylene

This can be obtained by This can be obtained by the polymerization of the polymerization of ethylene at 1500 atm ethylene at 1500 atm and a temperature 150 – and a temperature 150 – 250 250 00C in presence of C in presence of traces of oxygen. traces of oxygen.

POLYETHYLENE

Depending upon the density, they may Depending upon the density, they may be LDPE and HDPE. If we use free be LDPE and HDPE. If we use free radical initiator, LDPE is the product radical initiator, LDPE is the product while use of ionic catalysts results in the while use of ionic catalysts results in the formation of HDPE.formation of HDPE.

It is a rigid, waxy white solid. It is a rigid, waxy white solid. Translucent. It is permeable to many Translucent. It is permeable to many organic solvents. It crystallizes easily. organic solvents. It crystallizes easily.

LDPE has a density 0.91 to 0.925 g/cm3LDPE has a density 0.91 to 0.925 g/cm3 HDPE has a density 0.941 to 0.965 HDPE has a density 0.941 to 0.965

g/cm3g/cm3 HDPE is linear and has better chemical HDPE is linear and has better chemical

resistance. These are useful in the resistance. These are useful in the preparation of insulator parts, bottle preparation of insulator parts, bottle caps, flexible bottles, pipes etc.caps, flexible bottles, pipes etc.

USESUSES

These are useful in the preparation These are useful in the preparation of insulator parts, bottle caps, of insulator parts, bottle caps, flexible bottles, pipes etc.flexible bottles, pipes etc.

LDPE is used in making film and LDPE is used in making film and sheeting. Pipes made of LDPE are sheeting. Pipes made of LDPE are used for both agricultural, irrigation used for both agricultural, irrigation and domestic water line connections.and domestic water line connections.

HDPE is used in manufacture of toys HDPE is used in manufacture of toys and other household articles.and other household articles.

PVC :PVC :

Poly Vinyl Chloride is obtained by Poly Vinyl Chloride is obtained by heating a water emulsion of vinyl heating a water emulsion of vinyl chloride in presence of a small chloride in presence of a small amount of benzoyl peroxide or amount of benzoyl peroxide or hydrogen peroxide in an auto clave hydrogen peroxide in an auto clave under pressure.under pressure.

Vinyl chloride, so needed is generally Vinyl chloride, so needed is generally prepared by treating acetylene at 1 to prepared by treating acetylene at 1 to

1.5 atmospheres with hydrogen chloride 1.5 atmospheres with hydrogen chloride at 600C to 800C in the presence of at 600C to 800C in the presence of

metal chloride as catalyst.metal chloride as catalyst.

CH = CH + HCl CH = CH + HCl CH2 = CH- Cl CH2 = CH- Cl

Acetylene Vinyl Acetylene Vinyl chloridechloride

Nylon-6,6

It is prepared by Hexamethylene diamine and Adipic acid are polymerized in 1:1 ratio

USES/Applications:USES/Applications: Nylon-6,6 is mainly used for Nylon-6,6 is mainly used for

moulding purposes for gear moulding purposes for gear bearings and making car tyres, bearings and making car tyres, used for fibres etc. used for fibres etc.

This is mainly used in This is mainly used in manufacture of tyre cord. manufacture of tyre cord. Other uses include Other uses include manufacture of carpets, rope, manufacture of carpets, rope, fibre cloth etc.fibre cloth etc.

POLYESTERPOLYESTER

Terylene is a polyester fibre made Terylene is a polyester fibre made from ethylene glycol and from ethylene glycol and terephthalicacid. Terephtalic acid terephthalicacid. Terephtalic acid required for the manufacture of required for the manufacture of Terylene is produced by the catalytic Terylene is produced by the catalytic atmospheric oxidation of p-xylene.atmospheric oxidation of p-xylene.

Properties:Properties:

This occurs as a colourless rigid This occurs as a colourless rigid substance. substance.

This is highly resistant to mineral This is highly resistant to mineral and organic acids but is less and organic acids but is less resistant to alkalis. resistant to alkalis.

This is hydrophobic in nature.This is hydrophobic in nature. This has high melting point due to This has high melting point due to

presence of aromatic ring.presence of aromatic ring.

Uses:Uses:

It is mostly used for making It is mostly used for making synthetic fibres. synthetic fibres.

It can be blended with wool, cotton It can be blended with wool, cotton for better use and wrinkle for better use and wrinkle resistance. resistance.

Other application of polyethylene Other application of polyethylene terephthalate film is in electrical terephthalate film is in electrical insulation.insulation.

POLYESTERPOLYESTER

Terylene is a polyester fibre made Terylene is a polyester fibre made from ethylene glycol and from ethylene glycol and terephthalicacid. Terephtalic acid terephthalicacid. Terephtalic acid required for the manufacture of required for the manufacture of Terylene is produced by the catalytic Terylene is produced by the catalytic atmospheric oxidation of p-xylene.atmospheric oxidation of p-xylene.

THESE ARE ALSO POLYESTER PRODUCTS


This occurs as a colourless rigid This occurs as a colourless rigid substance. substance.

This is highly resistant to mineral This is highly resistant to mineral and organic acids but is less and organic acids but is less resistant to alkalis. resistant to alkalis.

This is hydrophobic in nature. This is hydrophobic in nature. This has high melting point due to This has high melting point due to

presence of aromatic ring.presence of aromatic ring.

Uses:Uses:

It is mostly used for making It is mostly used for making synthetic fibres. synthetic fibres.

It can be blended with wool, cotton It can be blended with wool, cotton for better use and wrinkle for better use and wrinkle resistance. resistance.

Other application of polyethylene Other application of polyethylene terephthalate film is in electrical terephthalate film is in electrical insulation.insulation.

TEFLON TEFLON or or

Poly tetra fluoro ethylene:Poly tetra fluoro ethylene:

Teflon is obtained by Teflon is obtained by polymerization of water-emulsion polymerization of water-emulsion tetrafluoroethylene, under tetrafluoroethylene, under pressure in presence of benzoyl pressure in presence of benzoyl peroxide as catalyst. peroxide as catalyst.


Due to the presence of highly Due to the presence of highly electronegative fluorine atoms and electronegative fluorine atoms and the reqular configuration of the the reqular configuration of the polytetrafluoro ethylene molecule polytetrafluoro ethylene molecule results in very strong attractive results in very strong attractive forces between the different chains.forces between the different chains.

These strong attractive forces give the These strong attractive forces give the material extreme toughness, high softening material extreme toughness, high softening point, exceptionally high chemical-resistance point, exceptionally high chemical-resistance towards all chemicals, high density, waxy towards all chemicals, high density, waxy touch, and very low coefficient of friction, touch, and very low coefficient of friction, extremely good electrical and mechanical extremely good electrical and mechanical properties: It can be machined, punched and properties: It can be machined, punched and drilled. drilled.

The material, however, has the disadvantage The material, however, has the disadvantage that it cannot be dissolved and cannot exist that it cannot be dissolved and cannot exist in a true molten state. Around 350in a true molten state. Around 35000c, it c, it sinters to form very viscous, opaque mass, sinters to form very viscous, opaque mass, which can be moulded into certain forms by which can be moulded into certain forms by applying high pressuresapplying high pressures

Uses:Uses:

As insulating material for motors, As insulating material for motors, transformers, cables, wires, fittings, transformers, cables, wires, fittings, etc, and for making gaskets, packing, etc, and for making gaskets, packing, pump parts, tank linings, chemical-pump parts, tank linings, chemical-carrying pipes, tubing’s and tanks, carrying pipes, tubing’s and tanks, etc,; for coating and impregnating etc,; for coating and impregnating glass fibres, asbestos fibers and glass fibres, asbestos fibers and cloths; in non-lubricating bearings cloths; in non-lubricating bearings and non-sticking stop-cocks etc.and non-sticking stop-cocks etc.

polymer science

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