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PLASTIC MATERIALS

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PLASTIC MATERIALS

Large and varied group

Consists of wholly or in part combination of carbon

with oxygen,hydrogen,nitrogen

and other organic or inorganic elements

Solid in finished stage or moulded stage

Liquid in manufacturing stage

Moulded by application of heat / pressure

Generally flexible

But can be made rigid,stiff,strong,weatherresistant,heat resistant,electrical resistant and if

required can be made electrically conductive also

Basic material of all Plastics is HYDRO CARBON

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PLASTIC MATERIALS

Two types of plastics are Thermo plastic andThermoset plastics

THERMOPLASTICS are either AMORPHOUS or

CRYSTALLINE in structure They form a Linear or Branched Molecular Chain

Formulated by Addition Polymerization

Available in Granules of 3x4mm Undergoes Physical change only, on Heating

Recyclable

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They are having molecules going in all

different directions and normallytransparent. They will undergo small

volumetric change when processing.

They are tougher and more flexible.

AMORPHOUS PLASTICS

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Since commercially perfect crystalline polymers are not

produced they are identified technically as semi-

crystalline thermoplastics. A crystalline area is stiffer and

stronger. It is difficult to process crystalline materials

due to high melt temperature, melt viscosity, shrinkage.

AMORPHOUS

CRYSTALLINE

SEMI-CRYSTALLINE PLASTICS

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PLASTIC MATERIALS

By adding different modifiers,additives,fillersand

Reinforcements many formulationsof Plastics are

derived (Approx.18,000)

Classification of Thermo Plastics:-

1.Commodity Plastics eg.PE,PS,PP,PVC

2.Engineering Plastics eg.ABS,PA,PC,PEEK

3.Speciality Plastics eg.Liquid Crystral Polymer

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THERMOSETS

Formulated by Condensation Polymerization.

Available in Fine Powder form.

A compound partially polymerized.

Undergoes irreversable chemical change by

application ofHEAT & PRESSURE.

Cross linked between molecules by the

reactive portion of Compound. Not reusable or recyclable.

Difficult to dispose off.

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Cross-linked

Giant macromolecule

Structurally set

Shape cannot be altered once moulded

THERMOSET PLASTICS

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Forms a Hard, Dense and Polished Shiny moulded

component.

Brittle, Highly Heat & Electrical Resistant

Has a Shelf life.

Eg. Phenol Formaldehyde

Melamine Formaldehyde

Urea Formaldehyde

Alkyds, Diallys, Polyurethane, Silicones,

Unsaturated Polyesters.

Thermosets are normally moulded by1. Compression moulding

2. Transfer moulding

3. Injection moulding

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PLASTIC MATERIALS AND

APPLICATION

Sl.

No.

Name of plastic Chief Properties Applications

1

2

Acrylo Nitrile

Butadiene Styerne

(A.B.S.)

Density = 1.05 gm./cc

Shrinkage = 0.5 %

Tm = 175 to 300 C

Cellulose acetate( C. A.) , Perspex

Density = 1.22 gm./ cc

Shrinkage = 0.5 %

Tm = 170 to 250 C

Translucent, Tough, Low

Temp.,Low Creep resistance,

Good Gloss & Aberration

resistantance,Low waterAbsorption,Good Electrical

resistant, Weatherability Fair,

Good Chemical resistance,

Electroplatable

Transparent, Tough, Costmoderate, Hard, Stiff, Surface-

Gloss good, 2.5% Water

absorption, Electrical resistance

Good, Resistance to Acids

nil,, Self extinguishing,

T.V.Cabinets,

Helmets,Grills,

Shoe heels, Slide -

rules, Automobileparts, Furnitures

Sun glass frames,

Pen barrels, Tool

handles, Brush

backs, Ornaments,

toys & Dolls

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PLASTIC MATERIALS AND APPLICATION

Sl.

No.


3

4

Nylon or Polyamide

Density = 1.15 gm./ccShrinkage =1.5 %

Tm = 250 C

Poly Acetal ( P.O.M )

Poly Oxy Methylene

Density = 1.4 gm./ cc

Shrinkage = 2.5 %

Tm = 175 to 250 C

Translucent, Tough, High

Temp., Creep resistance Good.Wear resistantance Excellent,

Good Chemical resistance,

Self Lubricating, Low Coeff. of

Friction, Self Extinguishing,

Water Absorption 4 to10%,

Electrically not Good

Translucent, Rigid, High Tensile

and Flexural Strengths, Fatigue

Resistance high, Lower

Elongation, Resistance to

Temp.&Chemical better, Impact& Aberration Resistance

Good, Dimensional Stability

Good, Lowest Coeff. Of

Friction, Self Lubricating,

Glossy, Electrically Good, Poor

Weather ability.

Gears, Cams,

Bearing surfaces,CoilForms,

Combs, Housings,

Battery Cases,

Gaskets, Soldering

Iron Handles

Gears, Cams,

Springs, Levers,

Clips, Clamps,

Housings, Bearing,

Pump Housings,Sprinklers,

Portable water

tanks, Valves,

Showerheads.

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Sl.

No.


5

6

Polycarbonate,(P.C)

Density = 1.2 gm./cc

Shrinkage = 0.6 %

Tm = 275 to 315 C

Polyethylene (P.E)

Density =0.91gm/ cc to

0.97 gm/ccShrinkage = 1.5 %

Tm = 200 to 280 C

Transparency 90%, Impact

strength High, Dimensionally

Stable, Good Chemical and Heat

Resistance, Low Coeff. of

Friction, Self Extinguishing,

Electrically Excellent, Shrinkage

uniform in all directions, Costly.

Translucent, Low density, Cheap,

Flexible, Low water absorption

(0.01%), Electrically very good,Good Heat stability, Inert to

Chemicals, Poor Weather ability.

Outdoor lighting,

Lens, Tool and

appliance housing,

Aircraft Interiors,

Automobile Lamp

housings.

Containers, Covers,

Buckets, Household

items, Toys &Furniture.

.

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Sl. No. Name of plastic Chief Properties Applications

7 PolymethylMethacrylate

(P.M.M.A) - Acrylic

Density = 1.15 gm/cc

Shrinkage = 0.5 %

Tm = 160o C

Transparent (92%) ,Hard, Rigid, Weather

ability Good,

Dimensionalstability very

Good, Decorative

Outstanding, Excellent-

Gloss, Chemically- Good.

Lenses, Outdoorlighting, m/c

Housings, Indoor

decorative

applications, Auto tail

lamps, Stop lights,

Instrument lenses,

Name plates, Dials,

Knobs, Signal lights.

8Polystyrene

( P. S )

General purpose &

High Impact

Density =1.05 gm/cc

Shrinkage = 0.5 %

Tm = 160 3000C

Transparent ( 90%), High

Gloss, Brittle, Rigid, High

Tensile strength, Low

Elongation, Electrically-Excellent, Dim. Stability -

Good, Less Water

absorption,

Weatherability Poor,

Chemically Good

Containers,

Packaging, Toys,

Household items,

Combs, Enclosures,Tape Cassettes,

Furnitures.

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Sl. No. Name of plastic Chief Properties Applications

9 Polypropylene (P.P)Density = 0.90 gm/cc

Shrinkage = 1.5 %

Tm = 200o C --

2800C

Translucent , , Very highTensile strength, Impact

strength and high Fatigue

resistance , flexible.

Excellent abrasion

resistance , low friction ,

poor weather ability ,excellent chemical

resistance,selfextinguishing

electroplatable.

Containers ,household items ,

hinged applications ,

battery cases , pump

parts , splash

guards, door panels ,

accelerator pedal.

10 Poly vinyl chloride

(PVC)

Density : 1.2 1.4gm/cc

Shrinkage = 0.5 %

Transparent , high impact

strength , weather ability

good , excellent chemicalresistance , electrically good

, self extinguishing , cheap ,

abrasion good , Low water

absorption.

Electrical cords ,

handle grips ,

vacuum cleanerparts , shoes , pipe

fittings , phonograph

records , chemical

containers .

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01 Plastic