plastic

plastic

Plastic is a synthetic material made from a wide range of

organic polymers such as polyethylene, PVC, nylon, etc., that

can be moulded into shape while soft, and then set into a

rigid or slightly elastic form.

Composition of plastic

Organic Polymers + Carbon + O2 +

Nitrogen Sulphur+

O r g a n i c P o l y m e r s m a y i n c l u d e :

C H A L K , S TA R C H , I V O R Y D U S T, W O O D F L O O R , Z I N C

O X I D E

Classification of plastic

There are many ways of classifying plastics. They can be

classified considering various aspects, as according to their:

1. Behaviour with respect to heating,

2. Structure, and

3. Physical and mechanical properties.

Classification of plastic

Behaviour with respect to heating Structure Physical and

mechanical properties

Thermo-plastics

Thermo-setting

Homogeneous

Heterogeneous

Rigid Plastics

Semi-rigid Plastics

Soft Plastics

Elastomers

Themoplastic & thermosetting

Basic difference between Thermoplastics and Thermosetting plastics

THERMOPLASTICS THERMO-SETTING PLASTICS

Thermoplastics variety softens by heat and hardens when cooled down. It can be used by remolding as many times as required.

Thermosetting plastics can not be reused .This variety requires a great pressure and momentary heat during molding which hardens on cooling.

Thermo-plastics The thermo-plastic or heat non-convertible group is the general term

applied to the plastics which becomes soft when heated and hard when

cooled.

Thermoplastic materials can be cooled and heated several times.

They can be recycled.

When thermoplastics are heated, they melt to a liquid. They also freeze

to a glassy state when cooled enough.

Thermoplastic can be moulded into any shape.

Thermo-plastics

Thermo-plastics

It may melt before passing to a gaseous state.

Allow plastic deformation when it is heated.

They are brittle and glossy.

They are soluble in certain solvents.

Swell in the presence of certain solvents.

Good resistance to creep.

PROPERTIES

Thermo-plastics

Thermoplastic materials have many features. Some products made from

thermoplastic materials are used for electronic applications. They protect

against electrostatic discharge and radio frequency interference.

High pressure polyethylene as applied to rigid material covered with electrical

machines, tubes, etc...

Low pressure polyethylene elastic material used for insulation of electrical cables,

etc...

Polystyrene applied for electrical insulation, handles of tools...

Polyamide used for making ropes, belts, etc...

PVC or polyvinyl chloride for the manufacture of insulation materials, pipes,

containers, etc...

Examples and applications of thermoplastic plastic materials

Thermo-plastics

Thermo-setting plastics

The thermo-setting or heat convertible group is the general term applied

to the plastics which become rigid when moulded at suitable pressure and

temperature.

This type of plastic passes originally through thermo-plastic stage. When

they are heated in temperature range of 127 ? C to 177 ? C, they set

permanently and further application of heat does not alter their form or

soften them.

But at the temperature of about 343 ?C, the charring occurs. This charring

is a peculiar characteristic of the organic substances.

Thermo-setting

Thermo-setting plastics

These are soluble in alcohol and certain organic solvents, when

they are in thermo-plastic stage. This property is utilized for making

paints and varnishes from these plastics.

These are durable, strong and hard.

They are available in a variety of beautiful colours.

They are mainly used in engineering application of plastics.

PROPERTIES

*Melamine Crockeries

Thermo-setting plasticsAPPLICATIONS

Epoxies

Properties: good dimensional stability, excellent mechanical and electrical properties, good resistance to heat and chemicals

Applications: electrical components requiring strength, tools and dies, fiber reinforced epoxies are used in structural components, tanks, pressure vessels, rocket motor casing

Phenolics

Properties: good dimensional stability, rigid, high resistance to heat, water, electricity, and chemicals

Applications: laminated panels, handles, knobs, electrical components; connectors, insulators

Thermo-setting plasticsAPPLICATIONS

Polyesters (thermosetting, reinforced with glass fibers)

Properties: good mechanical, electrical, and chemical properties, good resistance to heat and chemicals

Applications: boats, luggage, swimming pools, automotive bodies, chairs

Silicones

Properties: excellent electrical properties over a wide rang of temperature and humidity, good heat and chemical properties

Applications: electrical components requiring strength at high temp., waterproof materials, heat seals

Thermo-setting plastics

Electronic chips

Fibre-reinforced composites

Polymeric coatings

Spectacle lenses

Dental fillings

General Uses

Natural vs. synthetic polymers

NATURAL POLYMERS SYNTHETIC POLYMER

Thermoplastic polymer(Chemical composition do not change on heating)

Thermosetting polymer(Irreversible chemical process)

Remouldable Polymers Non-remouldable Polymers

These are brittle, glossy, elasticity, flexible

They possess matt effect, elasticity, and are flexible

Eg: Polyethylene, Polypropylene, Polystyrene, PVC

Eg: Rubber, Nylon, Glass Fibre, Cork

Structure based

Homogeneous Plastics

Heterogeneous Plastics

Homogeneous plastics

This variety of plastic contains carbon chain i.e. the plastics of this group

are composed only of carbon atoms and they exhibit homogeneous

structure.

Heterogeneous plastics

This variety of plastic is composed of the chain containing carbon and

oxygen, the nitrogen and other elements and they exhibit

heterogeneous structure.

Based on physical and chemical properties

Soft Plastics

Semi-rigid Plastics

Elastomers

Rigid Plastics

Rigid plastics

These plastics have a high modulus of elasticity and they retain

their shape under exterior stresses applied at normal or

moderately increased temperatures.

Semi-Rigid plastics

These plastics have a medium modulus of elasticity and the

elongation under pressure completely disappears, when pressure

is removed.

soft plastics

These plastics have a low modulus of elasticity and the

elongation under pressure disappears slowly, when pressure is

removed.

Soft plastics are available in a large range of colours, sizes and

particularly shapes.

USES: Used in making children’s toys eg: rattles etc., fishing baits.

Elastomers

These plastics are soft and elastic materials with a low modulus of

elasticity. They deform considerably under load at room

temperature and return to their original shape, when the load is

released. The extensions can range upto ten times their original

dimensions.

Bio-degradable Plastics Biodegradable plastic decomposes in the natural environment. It is

produced from biopolymers called polyhydroxyalkanoate (PHA). This

material is completely biodegradable.

Biodegradation of plastics can be achieved by enabling

microorganisms in the environment to metabolize the molecular

structure of plastic films to produce an inert humus like material that is

harmful to environment.

The use of bio-active compounds compounded with swelling agents

ensures that, when combined with heat and moisture, they expand the

plastic’s molecular structure and allow the bio-active compounds to

metabolise and neutralize the plastic.

Bio-degradable Plastics

Advantages & disadvantages

Under proper conditions biodegradable plastics can degrade to the

point where microorganisms can metabolize them.

This reduces the problems with litter and reduces harmful effects on

wildlife.

However degradation of biodegradable plastic occurs very slowly.

Proper composting methods are required to degrade the plastic,

which may actually contribute to carbon dioxide emissions.

Moulding compoundsSome of the moulding components are:

Catalyst

Fillers

Hardeners

Lubricants

Pigments

Plasticizers

Solvents

Catalysts These components are added to assist and accelerate the hardening

of resins.

For instance, the ester acts as catalyst for urea formaldehyde.

They are used for quick and complete polymerization.

fillers The fillers are inert materials and they impart strength, hardness and

other properties to the plastic.

The choice of filler should be carefully made.

It should be confirmed that the addition of a filler does not have

detrimental effect on other properties of plastic.

The filler may be used in the following forms-

Fibrous fillers

Laminated fillers

Power fillers

hardeners These compounds are added to increase the hardness of resin.

For instance, the hexamethylene tetramine acts as hardeners for

phenol formaldehyde.

lubricants The lubricants are applied on the surface of moulds so that the

articles of plastic do not stick to the moulds.

The application of lubricants on surface of moulds allows easy

removal of articles of plastic from the moulds.

The commonly used lubricants are graphite, parafine, wax, etc.

pigments The addition of dyes and pigments helps in two ways, namely, they act as fillers

an they impart desired colour to the plastic.

They should be durable and adequately fast to light.

The commonly used pigments are zinc oxide, barytes, etc.

The selection of pigments should be done in such a way that their addition does

not alter or affect the other properties of plastic.

plasticizers The plasticizers are the organic compounds which are oily in nature and low

molecular weight.

They are used to separate the polymer chain by a greater distance to make the

crystallization difficult.

These components are added to improve the plasticity and to impart softness to

the plastic.

They gives flexibility to the material and act like a lubricant.

The addition of plasticizers facilitates the moulding process of plastic articles.

The commonly used plasticizers in plastic are camphor, triacetin, tributyl

phosphate, etc.

The properties of plasticizers in plastic should not exceed 10% otherwise

strength of plastic will decrease.

solvents These components are added to dissolve the plasticizers.

For instance the alcohol is added in cellulose nitrate plastics to dissolve

camphor.

Fabrication

Following are the process involved in the fabrication of articles of

plastics:

Blowing

Calendering

Casting

Laminating

Moulding

blowing This method of lubrication of articles of plastic is more or less the same

as the one employed in the glass industry.

A lump of plastic material is taken and by blowing, it is converted into

hollow plastic articles such as jars, bottles, toys, etc.

calendering In this process the plastic material is allowed to pass between the

cylindrical rollers.

The process is used to prepare plain flat sheets of plastics.

The roller may be provided with artistic designs which will appear on

the finished product.

calendering

Casting This process is similar in principle to that of metal casting.

The resin is heated and when it is in plastic form, it is poured into the

mould.

The curing of articles is then done either with or without the

application of heat.

During curing the low pressure may be applied if necessary.

This process is used to prepare plastics of beautiful colours and it is

most suitable for cellulose plastics.

Casting

Laminating In this process, the thermosetting resin are just applied on sheets of

paper, asbestos, cloth, wood, glass, fibre, etc. and they are subjected to

heavy pressure by allowing them to pass through rollers to form plastic

laminates.

The thickness of sheets varies from 0.12 mm to 15 mm

Due to the pleasing finished surface, they are used for ornamental and

decorative purposes.

Laminating

moulding This is the most commonly adopted process for the fabrication of plastic

articles.

The general process consist in placing the raw materials in a mould and then

heating it.

The moulding can be done by various methods:

Compression moulding

Extrusion moulding

Injection moulding

Jet moulding

Transfer moulding

NOTE: The choice of moulding method will depend on the article to be prepared.

CLICK TO VIEW THE MOVIE

moulding

MOULDING MACHINE (PROCESS)

moulding

A VARIETY OF MOULDED ARCTICLES

properties APPEARANCE: Some plastics are completely transparent in appearance. With

the addition of suitable pigments, the plastics can be made to have appearance of

variety of attractive, opaque, stable and translucent colours.

CHEMICAL RESISTANCE: The plastics offer great resistance to moisture,

chemicals and solvents. The degree of chemical resistance depends on the

chemical composition of plastics. Many plastics are found to possess excellent

corrosion resistance. Hence they are used to convey chemicals.

DIMENSIONAL STABILITY: This property of plastic favours quite satisfactory with

that of other common engineering materials.

DUCTILITY: The plastics possess excellent electric insulating property. They are

far superior to ordinary electric insulators.

properties MAINTENANCE: It is easy to maintain plastic surfaces. They do not require any

protective coat of paints.

MELTING POINT: Most of the plastics have low melting point and the melting point

of some plastics is only about 50 ?C. They cannot therefore be used in positions having

high temperatures or to convey boiling water.

OPTICAL PROPERTY: Several types of plastics are transparent and translucent.

RECYCLING: The most environmentally aware people condemn the use of plastics

for the amount of pollution caused by them in disposal. The plastics used for soft-

drink bottles, milk and juice bottles, bread bags, syrup bottles, coffee cups, plastic

utensils, etc. can be conveniently recycled into carpets, detergent bottles, drainage

pipes, fencing, handrails, grocery bags, car battery cases, pencil holders, benches,

picnic tables, roadside posts, etc.

properties SOUND ABSORPTION: The acoustical boards are prepared by impregnating fibre-

glass with phenolic resins. This material has absorption coefficient of about 0.67.

STRENGTH: An ideal section of plastics for structural member has yet not been

designed. The plastics are reasonably strong. The strength of plastics may be

increased by reinforcing with various fibrous materials.

Following considerations are responsible to discourage the use of plastics

as the structural material:

1. The plastics are costly.

2. The plastics are subject to creep under constant heavy loads.

3. The behaviour of plastics is very sensitive to the changes in temperature.

4. The stiffness of plastics is very poor

properties THERMAL PROPERTY: The thermal conductivity of plastics is low and it can be

compared with that of wood. The foamed or expanded plastics are among the leading

thermal insulators.

WEATHER RESISTANCE: Only limited varieties of plastics can be exposed to weather.

The certain plastics are seriously affected by ultraviolet light in the presence of

sunlight. The resistance to sunlight of such plastics can be improved by incorporating

fillers and pigments which absorb or reflect the ultraviolet light at the surface. Thus

the interior of plastics is protected.

WEIGHT: The plastics, whether thermo-plastic or thermo-setting, have low specific

gravity, the average being 1.30 to 1.40. The light weight of plastics reduces the

transport costs and facilitates fixing.

Add to your knowledge

The Indian Petrochemical Corporation Ltd. (IPCL), near Baroda, has put a

commercial brand of plastics, known as the ‘Koylene’. It is the lightest of all

commercial known plastics and it is available in a wide range of grades. It is tailor-

made to suit various applications such as automotive and scooter parts, box

strappings, industrial woven fabrics, ball pen refills, drinking straws, etc. This

material possesses rigidity, good gloss, ability to withstand temperatures upto

100 ?C and easy processibility.

Uses of plastic

SECTION USED FOR JOINING PVC SHEET

ADVANTAGES of plastic

Corrosion resistance

Low electrical and thermal conductivity, insulator

Easily formed into complex shapes, can be formed, casted

and joined.

Wide choice of appearance, colors and transparencies

Ken Youssefi Mechanical Engineering 54

DISADVANTAGES of plastic

Low strength

Low useful temperature range (up to 600o F)

Less dimensional stability over period of time (creep effect)

Aging effect, hardens and become brittle over time

Sensitive to environment, moisture and chemicals

Poor machinibility

Uses of plastic There are more than 10000 different kinds of plastics available in the market

and their performance abilities span those of every other known material from

soft rubber to steel.

The typical uses of plastics in building are summarized as follows:

Bath and sink units Cistern ball floats Corrugated and plain sheets Decorative laminates and mouldings Electrical conduits Electrical Insulators Films for water proofing, damp proofing and concrete curing Floor tiles Foams for thermal insulation Jointless flooring

Lighting fixtures Overhead water tanks Paints and varnishes Pipes to carry cold water Roof lights Safety glass Wall tiles Water resistance adhesives

World consumption of plastic

COMPANIES-

GE, POLYGAL, GOODSALES,

SUNBEAM

COLOURS- NATURAL SMOKE GREEN BLUE

RATE DIFFERENCES-

Rates difference as per texture is Rs 15 to 20

PER SQ FT.

IT IS TRANSPORTED IN THE FORM OF ROLLS

PO

LYC

AR

BO

NATE S

HEETS

USES OF POLYCARBONATE SHEETS

Market Analysis

SIZE - 3X100 sq ft ,4X100 sq ft (FOR 1 mm)

7X20 sq ft, 7X40 sq ft (FOR 2 TO 12 mm)

THICKNESS - 1,2,4 ,6 ,8 ,10,12 mm

PVC PANELS

Market Analysis

THICKNESS RATES PER SQ. FT.

1 MM RS. 57

2 MM RS. 65

4 MM RS. 75

6 MM RS. 95

8 MM RS. 135

10 MM RS. 140

12 MM RS. 145

Market Analysis

DOMECONSTRUCTIONBY PVC SHEETS

Market Analysis

Market Analysis

Market Analysis

PVC DOORS

ThanksSeminar presented by:

Namit MittalDeepak SharmaUtkarsha SinghPavas Sharma

(B.Arch IV SEM)

Guided By:AR. Amrita Rastogi

Bibliography:Book on Engineering Materials

(Author-Rangwala)

http://en.wikipedia.org/wiki/Plastichttps://www.youtube.com/watch?v=H_3FHSOIv-Q