Plastics

organic high polymers

chainlike molecules that contain

carbon

Mesoamericans

1600 BC

natural rubber for balls, bands and

figurines.

Charles Goodyear

1800

discovery of vulcanization

Alexander parkes

1856

first man-made plastic

Bakelite

1900

first fully synthetic thermoset

Polyethylene Terephthalate (PET)

1941

credited to employees of the Calico

Printers Association

Modern plastics

oil, coal and natural gas with crude

oil

Naphtha

110 -180

main source of chemical building

blocks

Plastic Production

The start of making plastics is to

subject naptha to a cracking process

Complex organic chemical compounds

separated into smaller molecules

smaller molecules include ethylene,

propylene, butene and other

hydrocarbons

Thermosetting

converted into their final form

Thermoplastic

softened and become fused or

'plastic' by moderate heating

Polymers

large molecules made up of many

smaller molecules called Monomers.

initially produced as powders,

granules or laces

Polymerization

process of linking monomers to form

polymers

two kinds of chemical reaction

called condensation and addition

Addition Polymerization

Reaction of monomers without the

elimination of atoms

Condensation Polymerization

such as water, is eliminated

between functional groups

Blowing agents

expanded or foamed products can

be made from base polymers by the

addition

Colorants

colored by using either dyes or

pigments

Dyes

give transparent colors, and

pigments give opaque ones

Fillers

added to polymers in order to

modify their properties

good example=adding wood flour to

phenol formaldehyde

Protective agents

degraded by heat and light,

especially from the ultra violet light

in sunlight

UPVC

used in the manufacture of

drainpipes

Impact modifiers

Some plastics are designed to have

great impact strength

when added to other polymers

improve the impact resistance of a

product

based on acrylic polymers, are used

in conjunction with PVC

ABS

manufacture of car bumpers

Lubricants

help plastics flow in molds

waxy materials that act by reducing

the stickiness

Plasticizers

such as dioctylphthalate are added

to polymers in order to make the

resulting materials more flexible

can change unplasticised polyvinyl

chloride (UPVC)

Plastic Processing

extrusion, injection moulding, blow

moulding, vacuum forming,

extrusion blow moulding, rotational

moulding, calendaring, foaming and

compression moulding.

Extrusion

compared to squeezing toothpaste

out of a tube

Injection molding

most common of all plastics

manufacturing processes

Blow molding

compressed air is introduced

underneath a warmed sheet of

thermoplastic material

Vacuum Forming

opposite of blow moulding

Extrusion blow molding

article to be made has a narrow

neck, such as a bottle

combination of extrusion and blow

moulding

Rotational Molding

produce hollow thermoplastic

products such as drums, storage

tanks and litterbins

Compression Molding

carefully weighed amount of

thermosetting polymer is placed

into a preheated lower mould cavity

Calendering

used to produce plastic sheeting and

products such as floor tiles, coated

fabrics and coverings for car

interiors

Fused thermoplastic

extruded on to heated rotating

rollers

film

cooled by jets of air or water