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ABS : a TERPOLYMER made from three MONOMERS,
acrylonitrile, butadiene and
styrene.
Acrylonitrile and styrene provide
chemical resistance
( see SAN ),
butadiene adds impact resistance and
makes the
plastic suitable for
furniture, computer housings etc.
ACRYLIC:
a hard thermoplastic made from acrylic
acid or a derivative of acrylic acid.
Best known as a glass substitute under
the trade names Perspex, Lucite and
Plexiglas.
AMINO PLASTICS : Plastics made from ammonia based
compounds, namely UREA FORMALDEHYDE
and MELAMINE FORMALDEHYDE.
ANILINE BROWN : An important dye, originally obtained
from indigo, now produced
synthetically. It turns brown on
exposure to the air, and was used
to
paint tortoiseshell markings on sheet
celluloid.
BAKELITE : The trade name for plastics produced
by Bakelite
Limited in England and the
Bakelite Corporation in America. Still
refers to these materials but is
frequently used as a generic name for
phenol formaldehyde ( PHENOLIC ).
BLOW MOULDING : A cheap method for mass producing
hollow objects by blowing air into a
hollow tube of softened THERMOPLASTIC
POLYMER, so that it expands to line
the mould.
CASTING : Simple forming of a solid object by
pouring resin into a mould, and
CURING at room temperature.
CELLOPHANE : A Du Pont trade
name for film made from
regenerated wood pulp ( CELLULOSE ).
CELLULAR
PLASTICS : A hard or soft foamed plastic with
cells of air caught within the
material.
CELLULOID : See CELLULOSE NITRATE.
CELLULOSE
: The fibrous matter in all plant cells,
with a long chain molecular structure.
The most common sources used for making
plastics are cotton fibres and
wood pulp
CELLULOSE ACETATE: A tough thermplastic made from CELLULOSE
in the form of cotton linters, treated
with acetic acid and acetic anhydride.
Widely used as aircraft dope during the
First World War. It was welcomed as a
fire resistant alternative to CELLULOSE
NITRATE. Now used for many domestic
mouldings such as spectacle frames,
toothbrush handles, and as transparent
packaging film.
CELLULOSE -
ACETATE BUTYRATE : A thermoplastic made from CELLULOSE
treated with acetic and butyric acids.
Transparent, opaque or coloured,
with
excellent moulding qualities, it was
used where more moisture
resistance and
dimensional stability than cellulose
acetate was
required.
CELLULOSE NITRATE : An inflammable thermoplastic made from
CELLULOSE treated with nitric and
sulphuric acids. With camphor as
a PLASTICIZER it was patented as
Celluloid in America in 1869.
COLD MOULDED -
PLASTICS : Plastics moulded under pressure at
room temperature,
and cured by heat.
COMPRESSION -
MOULDING : The most common method for forming
thermosetting resins such as BAKELITE
into ashtrays, radios etc. The
moulding powder, usually with a filler
is placed in the lower ' female
' part
of a two part mould. The top part closed
on to it, heat and
pressure are applied,
the plastic flows around the mould and
the
final moulding is ejected.
COPOLMER : A POLYMER (plastic ) made by
POLYMERIZING two MONOMERS, eg styrene -
acrylonitrile ( SAN ).
CROSS
LINKING : The forming of chemical bonds between
the molecular chains of a plastic
during CURING so that it cannot be re-
softened and re-moulded, thus becoming
a THERMOSET.
CURING : The forming of a polymer by
POLYMERIZATION
and/or CROSS - LINKING.
DIE : Steel tool for shaping material by
EXTRUSION.
ELASTOMER : A synthetic plastic with the flexible
properties of rubber.
EPOXY ( EPOXIDE ) -
RESIN A very tough THERMOSETTING
resin used
as a coating, or reinforced to make
mouldings or laminates.
ESTER : A compound produced by the reaction
between an acid
and an alcohol.
EXTRUSION : Process similar to making spaghetti for
moulding plastics into continous lengths
of pipes, rods and profiles. The
softened material is forced through a
shaped DIE.
FILLER :
Inert material added to a polymer to
improve its properites. Usually in
powder or fibre form such as wood pulp,
cotton flock and talc.
FLASH
: A line of excess plastic forced out of a
mould along the PARTING LINE leaving a
small ridge. It sometimes has to be
filed off.
FLOW
LINES : Patterns visible in a moulding
indicating the direction of the flow of
the molten plastic in the mould. Usually
these patterns are painted over, but
they can also be used decoratively.
FUCHSIN : A synthetic dye, also known as magenta,
named after the brilliant colours of
the fuchsia flower.
GRP : Glass reinforced polyester, ie poyester
resin strengthened by
glass fibres,
making the resin, which has no strength
of its own,
into a very tensile
material. Widely used to build boats,
furniture
and cars.
GUN COTTON : CELLULOSE treated with nitric acid
with
approximately 13% nitrogen
content (as against 11% for
CELLULOID ).
Used as an explosive
propellant.
HARD RUBBER : The VULCANIZATION
process taken to
the extreme, when rubber becomes
extremely hard and
loses all
elasticity.
HIPS : High impact polystyrene ( see
-
POLYSTYRENE ).
INJECTION MOULDING : The most widely used high speed
process for mass producing plastic
articles. Granules are heated and
forced under pressure into a mould,
which can be single cavity for a
bucket or chair, or multi cavity
for combs and other small objects.
LLDPE : Linear low density polyethylene, a
new type of low density
POLYTHENE.
MELAMINE : Melamine formaldehyde, a thermoset
produced
by reacting
( triaminotriazine ) with
formaldehyde. A tough glossy
plastic usually strengthened with a
filler of wood pulp.
MOLECULAR WEIGHT : The total of the atomic weights of
all the atoms forming a molecule.
See POLYMER.
MONOMER : A simple low molecular weight
compound. POLYMERIZATION links
monomers together to form high
molecular
weight POLYMERS.
MOTTLE : The effect of incomplete blending
of
coloured moulding powders,
originally devised to simulate
wood grain,
marble and other
natural patterns. Powders or
granules of different
sizes are
very effective, and mineral
particles and pearl essence create
pearly nacreous colours.
NYLON : Not one material but a group of
very tough and flexible materials
called polyamides. Thermoplastic
and usually found as fibres or
used solid, as gears, zips and
more
recently as dyed jewellery.
ORGANIC COMPOUNDS : Compounds containing carbon in
their molecular make up. Nearly
all plastics and rubbers are
based on
carbon.
PARTING LINE A line on a moulding indicating
where the halves
of a mould
closed together.
PHENOLIC Shortened version of phenol
-
formaldehyde ( see BAKELITE ).
Phenolic is usually reinforced
with a FILLER, but cast phenolic
has no filler and can be
translucent. It can be easily
coloured and was used decoratively
for
jewellery, radio cabinets and
all kinds of ornaments.
PLASTICIZER :
A substance added to the POLYMER to
make it more flexible and easier to
mould.
PLASTISOL : PVC paste fr coating fabrics, foam
furniture and
metal parts with a
rubbery skin.
POLYCARBONATE : A very tough thermoplastic,
usually
found as a substitute for glass, eg:
vandal proof telephone kiosks,bullet
proof shields, baby bottles and
picnicware.
POLYESTERS
: Complex ESTER compounds which are
thermosetting and can be POLYMERIZED
at room temperature, eg GRP.
POLYMER : Another word for a plastic material:
one which has been made from chains
of molecules of one or more MONOMERS.
Polymers (plastics) are ORGANIC
substances of high MOLECULAR WEIGHT,
made
from hundreds or thousands of
molecules linked together in a
repeating
chain pattern ( also known
as macromolecules ).
POLYMERIZATION : The chemical
process of linking
MONOMERS to form new compounds called
POLYMERS. For
example,ethylene is
polymerized into polyethylene,
( polythene for short
).
POLYPROPYLENE : A thermoplastic polymerized from
propene, very close
to polythene in
molecular structure, but harder,
stronger and less flexible.
POLYSTYRENE : A brittle.water white thermoplastic
polymerized from styrene
-
( phenylethylene ). The brittleness is
overcome by adding some butadiene,
which results in toughened polystyrene
also known as high impact polystyrene
( HIPS ), a COPOLYMER of butadiene
and styrene. Expanded polystyrene is
the rigid white foam used for
packaging.
POLYTHENE
: A Du Pont trade name, used as a generic
name in Britain for polyethylene, the
most widely used plastic in the world.
Low density polythene is very flexible:
high density polythene is more rigid
with a higher softening point, and can
therefore be sterilized by steam.
POLYURETHANE : A rubbery plastic usually found in the
form of expanded soft foam for
upholstery and rigid foam for insulation
and also as an ELASTOMER. Self skinned
soft foam has a flexible tough skin
formed during moulding.
PVAC ( PVA ) : Polyvinyl acetate, most familiar as a
white wood glue and as emulsion paint.
PVC : Polyvinyl chloride, a hard, rigid
thermoplastic. Plasticized PVC is
the softened type, and is mixed with
a PLASTICIZER.
PVC - PVAC COPOLYMER : Vinyl chloride and vinyl acetate
copolymerize
to form a very tough and
flexible vinyl used for inflatable
furniture
and structures, and pressed
into records.
RESIN : A word synonymous
with plastic,
referring usually to the
unPOLYMERIZED material.
SAN : Styrene-acrylonitrile, much stronger
than POLYSTYRENE as it has been
modified by the addition of chemical
- resistant acrylonitrile.
SELF SKINNED FOAM : Soft or rigid foam with a tough
surface formed during moulding when
foamed cells compact against the
inside surface of the mould.
SINK MARK : A depression on the surface of a
moulding particularly where there is
a rib on the other side. It is
caused by contraction of the plastic
in the mould.
SPRUE : The part through which plastic flows
from the nozzle into the mould during
the injection moulding process. The
word also means the small, hard piece
which remains, and which is then
broken off, leaving a characteristic
round scar.
TERPOLYMER :
A COPOLYMER composed of three MONOMERS.
THERMOFORMING : The shaping of heat softened
thermoplastic sheet through heat and/
or vacuum.
THERMOPLASTIC : A
plastic material which, when
softened in a mould under heat and
pressure,
forms a shape which can be
re softened and re moulded, eg:
polythene, acrylic,
PVC, and nylon.
THERMOSET : A plastic which under heat and
pressure polymerizes
into a form
which cannot be re softened due to
CROSSLINKING of the molecules.
It is
therefore used for components such as
light fittings, saucepan handles
and
ashtrays.
UREA FORMALDEHYDE : Also called urea, a thermosetting
AMINO PLASTIC based on the reaction of
synthetic urea condensed with
formaldehyde.
UREA THIOUREA -
FORMALDEHYDE : The earlier and not so tough version
of urea formaldehyde.
VACUUM FORMING ; SEE THERMOFORMING.
VISCOSE
RAYON ; Fillaments extruded from a viscous
natural CELLULOSE made from wood pulp.
VULCANIZATION : The process which makes rubber
mouldings elastic and rubbery.
WATER WHITE : A grade of colour which looks like
clear water.
WITNESS
MARKS : The scars left on the object by the
ejector pins as they push the
moulding out of its mould.
end.
Conservation of Plastics Collections:
IT'S BAKELITE YOU KNOW !!!! ( WWW.BAKELITEMAN.COM )
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