Plastics
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Transcript of Plastics
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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
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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
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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