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What is Plastic?
A PLASTIC material is any of a wide range of synthetic or semi-synthetic organic solids that
can be molded into shape while soft and then set into a rigid or slightly elastic form. The
name is derived from the fact that in the semi-liquid state, plastic is malleable, or have the
property ofplasticity. Plasticity is the deformation of a material undergoing non-reversible
changes of shape in response to applied forces. For example, a solid piece of metal being bent
or pounded into a new shape displays plasticity if permanent changes occur within the
material itself.
HistoryThe development of plastic has come from the use of natural plastic materials (e.g., chewing
gum, shellac) to the use of chemically modified natural materials (e.g., rubber, nitrocellulose,
collagen, galalite) and finally to completely synthetic molecules (e.g., bakelite, epoxy,
polyvinyl chloride, polyethylene).
Plastic material started in 1839, when an American inventor, Charles Goodyear was
experimenting with the sulfur treatment of natural rubber when, according to legend, he
dropped a piece of sulfur-treated rubber on a stove. The rubber seemed to have improved
properties, and Goodyear followed up with further experiments, and developed a process
known as "vulcanization" that involved cooking the rubber with sulfur. Compared to
untreated natural rubber, Goodyear's vulcanized rubber was stronger, more resistant to
abrasion, more elastic, much less sensitive to temperature, impermeable to gases, and highly
resistant to chemicals and electric current.
The first human-made plastic, parkesine had an inauspicious birth. An Englishman,
Alexander Parkes, looking for collodion in his medicine cabinet to staunch a wound,
discovered that it had gelled into a tough rubbery substance. He was an enterprising man who
saw the possibilities, if this substance could be molded. Unfortunately, molding required heat,
and heating always made the substance explode. Licking his wounds, Parkes worked on, and
finally produced a suitable mixture of collodion, camphor, and ethanol. Parkesine, the first
synthetic plastic, was launched in 1865, and the Xylonite company was formed a year later.
http://en.wikipedia.org/wiki/Plasticity_%28physics%29http://en.wikipedia.org/wiki/Deformationhttp://en.wikipedia.org/wiki/Chewing_gumhttp://en.wikipedia.org/wiki/Chewing_gumhttp://en.wikipedia.org/wiki/Shellachttp://en.wikipedia.org/wiki/Rubberhttp://en.wikipedia.org/wiki/Nitrocellulosehttp://en.wikipedia.org/wiki/Collagenhttp://en.wikipedia.org/wiki/Galalitehttp://en.wikipedia.org/wiki/Bakelitehttp://en.wikipedia.org/wiki/Epoxyhttp://en.wikipedia.org/wiki/Epoxyhttp://en.wikipedia.org/wiki/Bakelitehttp://en.wikipedia.org/wiki/Galalitehttp://en.wikipedia.org/wiki/Collagenhttp://en.wikipedia.org/wiki/Nitrocellulosehttp://en.wikipedia.org/wiki/Rubberhttp://en.wikipedia.org/wiki/Shellachttp://en.wikipedia.org/wiki/Chewing_gumhttp://en.wikipedia.org/wiki/Chewing_gumhttp://en.wikipedia.org/wiki/Deformationhttp://en.wikipedia.org/wiki/Plasticity_%28physics%298/4/2019 Plastic and Construction
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The next major revolution of plastic is celluloid. Celluloid is derived from cellulose and
alcoholized camphor. John Wesley Hyatt invented celluloid as a substitute for the ivory in
billiard balls in 1868. He first tried using collodion a natural substance, after spilling a bottle
of it and discovering that the material dried into a tough and flexible film. However, the
material was not strong enough to be used as a billiard ball, until the addition of camphor, a
derivative of the laurel tree. The new celluloid could be moulded with heat and pressure into
a durable shape.
Next, the first plastic based on a synthetic polymer, was made from phenol and formaldehyde
by synthesis methods invented in 1907, by Leo Hendrik Baekeland, a Belgian-born
American. He called the new material Bakelite.
Bakelite was a purely synthetic material, not based on any material or even molecule found in
nature. It was also the first thermosetting plastic. Conventional thermoplastics can be
moulded and then melted again, but thermosetting plastics form bonds between polymers
strands when cured, creating a tangled matrix that cannot be undone without destroying the
plastic. Thermosetting plastics are tough and temperature resistant.
The next major thrust in the development of plastics took place in the 1920s with the
introduction of cellulose acetate (which is similar in structure to cellulose nitrate (celluloid),
but safer to process and use), ureaformaldehyde (which can be processed like the phenolics,
but can also be molded into light colored articles that are more attractive than the blacks and
browns in which phenolics are available), and polyvinyl chloride (PVC, or vinyl, as it is
commonly called). Nylon was also developed in the late 1920s through the classic research of
W.T. Carothers.
The decade of the 1950s saw the introduction of polypropylene and the development of acetal
and polycarbonate, two plastics that, along with nylon, came to form the nucleus of a sub-
group in the plastics family known as the "engineering thermoplastics." Their outstanding
impact strength and thermal and dimensional stability enabled them to compete directly and
favourably with metal in many applications.
http://en.wikipedia.org/wiki/Leo_Hendrik_Baekelandhttp://en.wikipedia.org/wiki/Belgian-Americanhttp://en.wikipedia.org/wiki/Belgian-Americanhttp://en.wikipedia.org/wiki/Belgian-Americanhttp://en.wikipedia.org/wiki/Belgian-Americanhttp://en.wikipedia.org/wiki/Leo_Hendrik_Baekeland8/4/2019 Plastic and Construction
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The Development of Plastic
1868 - Cellulose Nitrate
1909 - Phenol-Formaldehyde
1927 - Cellulose Acetate
1927 - Polyvinyl Chloride
1929 - Urea Formaldehyde
1935 - Ethyl Cellulose
1936 - Acrylic
1936 - Polyvinyl Acetate
1938 - Nylon
1942 - Polyester
1943 - Silicone
1947 - Epoxy
Types of Plastic
As of now, there exist hundreds of different types of plastics, in terms of its chemical formula.
Generally, plastics can be classified into two, namely thermosetting and thermoplastic. The
thermosetting plastics are those that cannot be soften again, after being exposed to heat and
pressure. On the action of heat and pressure, the molecular chain of thermosetting plastics
become cross-linked and therefore forbids the slippage when pressure & heat are reapplied.
On the other hand, the thermoplastic are those that can be soften again and again & remade
by the action of heat and pressure. On the action of heat and pressure, the molecular chain ofthermoplastics undergoes change and the polymers slide past each other, which result in the
property of plasticity.
Thermosetting materials are generally stronger than thermoplastic materials due to this 3-D
network of bonds (cross-linking), and are also better suited to high-temperature applications
up to the decomposition temperature. However, they are more brittle. Many thermosetting
polymers are difficult to recycle.
Some examples of thermosetting materials are:
Polyester fibreglass systems: Vulcanized rubber Bakelite, a phenol-formaldehyde
resin
Duroplast Urea-formaldehyde
Melamine resin Epoxy resin Polyimides Cyanate Esters or Polycyanurates Mold or Mold Runners
http://en.wikipedia.org/wiki/Thermoplastichttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Vulcanizationhttp://en.wikipedia.org/wiki/Bakelitehttp://en.wikipedia.org/wiki/Duroplasthttp://en.wikipedia.org/wiki/Urea-formaldehydehttp://en.wikipedia.org/wiki/Melamine_resinhttp://en.wikipedia.org/wiki/Epoxyhttp://en.wikipedia.org/wiki/Polyimideshttp://en.wikipedia.org/wiki/Polyimideshttp://en.wikipedia.org/wiki/Epoxyhttp://en.wikipedia.org/wiki/Melamine_resinhttp://en.wikipedia.org/wiki/Urea-formaldehydehttp://en.wikipedia.org/wiki/Duroplasthttp://en.wikipedia.org/wiki/Bakelitehttp://en.wikipedia.org/wiki/Vulcanizationhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Thermoplastic8/4/2019 Plastic and Construction
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Some examples ofthermoplastic materials are:
Acrylonitrile butadiene styrene(ABS)
Acrylic (PMMA) Celluloid Cellulose acetate Fluoroplastics (PTFE, alongside
with FEP, PFA, CTFE, ECTFE,
ETFE)
Kydex Liquid Crystal Polymer (LCP) Polyacrylonitrile (PAN or
Acrylonitrile)
Polyamide (PA or Nylon) Polyamide-imide (PAI) Polyaryletherketone (PAEK or
Ketone)
Polybutadiene (PBD) Polybutylene (PB) Polybutylene terephthalate (PBT) Polycaprolactone (PCL) Polychlorotrifluoroethylene
(PCTFE)
Polyethylene terephthalate (PET) Polycarbonate (PC)
Polyhydroxyalkanoates (PHAs) Polyketone (PK) Polyester Polyethylene (PE) Polyetheretherketone (PEEK) Polyetherketoneketone (PEKK) Polyetherimide (PEI) Polyethersulfone (PES) Polyimide (PI) Polylactic acid (PLA) Polymethylpentene (PMP) Polyphenylene oxide (PPO) Polyphenylene sulfide (PPS) Polyphthalamide (PPA) Polypropylene (PP) Polystyrene (PS) Polysulfone (PSU) Polytrimethylene terephthalate
(PTT)
Polyurethane (PU) Polyvinyl acetate (PVA) Polyvinyl chloride (PVC) Polyvinylidene chloride (PVDC) Styrene-acrylonitrile (SAN)
http://en.wikipedia.org/wiki/Thermoplastichttp://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrenehttp://en.wikipedia.org/wiki/Polymethyl_methacrylatehttp://en.wikipedia.org/wiki/Celluloidhttp://en.wikipedia.org/wiki/Cellulose_acetatehttp://en.wikipedia.org/wiki/Fluoropolymerhttp://en.wikipedia.org/wiki/PTFEhttp://en.wikipedia.org/wiki/CTFEhttp://en.wikipedia.org/wiki/ECTFEhttp://en.wikipedia.org/wiki/ETFEhttp://en.wikipedia.org/wiki/Kydexhttp://en.wikipedia.org/wiki/Liquid_Crystal_Polymerhttp://en.wikipedia.org/wiki/Polyacrylonitrilehttp://en.wikipedia.org/wiki/Polyamidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/wiki/Polybutadienehttp://en.wikipedia.org/wiki/Polybutylenehttp://en.wikipedia.org/wiki/Polybutylene_terephthalatehttp://en.wikipedia.org/wiki/Polycaprolactonehttp://en.wikipedia.org/wiki/Polychlorotrifluoroethylenehttp://en.wikipedia.org/wiki/Polyethylene_terephthalatehttp://en.wikipedia.org/wiki/Polycarbonatehttp://en.wikipedia.org/wiki/Polyhydroxyalkanoateshttp://en.wikipedia.org/wiki/Polyketonehttp://en.wikipedia.org/wiki/Polyesterhttp://en.wikipedia.org/wiki/Polyethylenehttp://en.wikipedia.org/wiki/Polyetheretherketonehttp://en.wikipedia.org/w/index.php?title=Polyetherketoneketone&action=edit&redlink=1http://en.wikipedia.org/wiki/Polyetherimidehttp://en.wikipedia.org/wiki/Polyethersulfonehttp://en.wikipedia.org/wiki/Polyimidehttp://en.wikipedia.org/wiki/Polylactic_acidhttp://en.wikipedia.org/wiki/Polymethylpentenehttp://en.wikipedia.org/wiki/Polyphenylene_oxidehttp://en.wikipedia.org/wiki/Polyphenylene_sulfidehttp://en.wikipedia.org/wiki/Polyphthalamidehttp://en.wikipedia.org/wiki/Polypropylenehttp://en.wikipedia.org/wiki/Polystyrenehttp://en.wikipedia.org/wiki/Polysulfonehttp://en.wikipedia.org/wiki/Polytrimethylene_terephthalatehttp://en.wikipedia.org/wiki/Polyurethanehttp://en.wikipedia.org/wiki/Polyvinyl_acetatehttp://en.wikipedia.org/wiki/Polyvinyl_chloridehttp://en.wikipedia.org/wiki/Polyvinylidene_chloridehttp://en.wikipedia.org/wiki/Styrene-acrylonitrilehttp://en.wikipedia.org/wiki/Styrene-acrylonitrilehttp://en.wikipedia.org/wiki/Polyvinylidene_chloridehttp://en.wikipedia.org/wiki/Polyvinyl_chloridehttp://en.wikipedia.org/wiki/Polyvinyl_acetatehttp://en.wikipedia.org/wiki/Polyurethanehttp://en.wikipedia.org/wiki/Polytrimethylene_terephthalatehttp://en.wikipedia.org/wiki/Polysulfonehttp://en.wikipedia.org/wiki/Polystyrenehttp://en.wikipedia.org/wiki/Polypropylenehttp://en.wikipedia.org/wiki/Polyphthalamidehttp://en.wikipedia.org/wiki/Polyphenylene_sulfidehttp://en.wikipedia.org/wiki/Polyphenylene_oxidehttp://en.wikipedia.org/wiki/Polymethylpentenehttp://en.wikipedia.org/wiki/Polylactic_acidhttp://en.wikipedia.org/wiki/Polyimidehttp://en.wikipedia.org/wiki/Polyethersulfonehttp://en.wikipedia.org/wiki/Polyetherimidehttp://en.wikipedia.org/w/index.php?title=Polyetherketoneketone&action=edit&redlink=1http://en.wikipedia.org/wiki/Polyetheretherketonehttp://en.wikipedia.org/wiki/Polyethylenehttp://en.wikipedia.org/wiki/Polyesterhttp://en.wikipedia.org/wiki/Polyketonehttp://en.wikipedia.org/wiki/Polyhydroxyalkanoateshttp://en.wikipedia.org/wiki/Polycarbonatehttp://en.wikipedia.org/wiki/Polyethylene_terephthalatehttp://en.wikipedia.org/wiki/Polychlorotrifluoroethylenehttp://en.wikipedia.org/wiki/Polycaprolactonehttp://en.wikipedia.org/wiki/Polybutylene_terephthalatehttp://en.wikipedia.org/wiki/Polybutylenehttp://en.wikipedia.org/wiki/Polybutadienehttp://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamidehttp://en.wikipedia.org/wiki/Polyacrylonitrilehttp://en.wikipedia.org/wiki/Liquid_Crystal_Polymerhttp://en.wikipedia.org/wiki/Kydexhttp://en.wikipedia.org/wiki/ETFEhttp://en.wikipedia.org/wiki/ECTFEhttp://en.wikipedia.org/wiki/CTFEhttp://en.wikipedia.org/wiki/PTFEhttp://en.wikipedia.org/wiki/Fluoropolymerhttp://en.wikipedia.org/wiki/Cellulose_acetatehttp://en.wikipedia.org/wiki/Celluloidhttp://en.wikipedia.org/wiki/Polymethyl_methacrylatehttp://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrenehttp://en.wikipedia.org/wiki/Thermoplastic8/4/2019 Plastic and Construction
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Material properties of some Thermoplastics
Name Symb
ol
Density
[g/cm^3
]
Tensile
strength
[MPa]
Flexural
Strengt
h
[MPa]
Elastic
Modul
us
[GPa]
Elongati
on at
rupture
[%]
Thermal
stability
[C]
Expansi
on at
20C
[10^-
6/C]
High Density
PolyethyleneHDPE 0.95 31 40 1.86 100 120 126
Low Density
PolyethyleneLDPE 0.92 17 14 0.29 500 90 160
Polyvinyl
ChloridePVC 1.44 47 91 3.32 60 80 75
Polypropylene PP 0.91 37 49 1.36 350 150 90
Polyethylene
terephthalatePET 1.35 61 105 1.35 170 120 70
Polymethylmet
hacrylate
PMM
A1.19 61 103 2.77 4 100 65
Polycarbonate PC 1.2 68 95 2.3 130 120 66
Acrylonitrile
butadiene
styrene
ABS 1.05 45 70 2.45 33 70 90
PolyamideNylon
61.13 60 91 2.95 60 110 66
Polyimide PI 1.38 96 143 3.1 7 380 43
Polysulfone PSF 1.25 68 115 2.61 75 160 56
Polyamide-
imide,
electrical grade
PAI 1.41 138 193 4.1 12 260 30
Polyamide-
imide, bearing
grade
PAI 1.46 103 159 5.5 6 260 25
Polytetrafluoro PTFE 2.17 24 33 0.49 300 260 95
http://en.wikipedia.org/wiki/Polyethylenehttp://en.wikipedia.org/wiki/Polyethylenehttp://en.wikipedia.org/wiki/Polyvinyl_Chloridehttp://en.wikipedia.org/wiki/Polyvinyl_Chloridehttp://en.wikipedia.org/wiki/Polypropylenehttp://en.wikipedia.org/wiki/Polyethylene_terephthalatehttp://en.wikipedia.org/wiki/Polyethylene_terephthalatehttp://en.wikipedia.org/wiki/Polymethylmethacrylatehttp://en.wikipedia.org/wiki/Polymethylmethacrylatehttp://en.wikipedia.org/wiki/Polycarbonatehttp://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrenehttp://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrenehttp://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrenehttp://en.wikipedia.org/wiki/Polyamidehttp://en.wikipedia.org/wiki/Polyimidehttp://en.wikipedia.org/wiki/Polysulfonehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polytetrafluoroethylenehttp://en.wikipedia.org/wiki/Polytetrafluoroethylenehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polysulfonehttp://en.wikipedia.org/wiki/Polyimidehttp://en.wikipedia.org/wiki/Polyamidehttp://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrenehttp://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrenehttp://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrenehttp://en.wikipedia.org/wiki/Polycarbonatehttp://en.wikipedia.org/wiki/Polymethylmethacrylatehttp://en.wikipedia.org/wiki/Polymethylmethacrylatehttp://en.wikipedia.org/wiki/Polyethylene_terephthalatehttp://en.wikipedia.org/wiki/Polyethylene_terephthalatehttp://en.wikipedia.org/wiki/Polypropylenehttp://en.wikipedia.org/wiki/Polyvinyl_Chloridehttp://en.wikipedia.org/wiki/Polyvinyl_Chloridehttp://en.wikipedia.org/wiki/Polyethylenehttp://en.wikipedia.org/wiki/Polyethylene8/4/2019 Plastic and Construction
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ethylene
Polyetherimide PEI 1.27 105 151 2.9 60 210 31
Polyether ether
ketonePEEK 1.32 100 3.6 50 343
Polyaryletherk
etone (strong)PEAK 1.46 136 213 12.4 2.1 267
Polyaryletherk
etone (tought)PEAK 1.29 87 124 3 40 190
Self-reinforced
polyphenyleneSRP 1.19 152 234 5.52 10 151
Polyamide-
imide
PAI 1.42 152 241 4.9 15 278
Apart from this classification, plastics have also been divided into seven different types by
the plastic industry. These seven types of plastics are:
Polymer
TypesExamples of applications Symbol
Polyethylene
TerephthalateFizzy drink and water bottles. Salad trays.
High Density
PolyethyleneMilk bottles, bleach, cleaners and most shampoo bottles.
Polyvinyl
Chloride
Pipes, fittings, window and door frames (rigid
PVC). Thermal insulation (PVC foam) and automotive
parts.
Low Density
PolyethyleneCarrier bags, bin liners and packaging films.
Polypropylene
Margarine tubs, microwaveable meal trays, also
produced as fibres and filaments for carpets, wall
coverings and vehicle upholstery.
http://en.wikipedia.org/wiki/Polytetrafluoroethylenehttp://en.wikipedia.org/wiki/Polyetherimidehttp://en.wikipedia.org/wiki/PEEKhttp://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/w/index.php?title=Self-reinforced_polyphenylene&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Self-reinforced_polyphenylene&action=edit&redlink=1http://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/wiki/Polyamide-imidehttp://en.wikipedia.org/w/index.php?title=Self-reinforced_polyphenylene&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Self-reinforced_polyphenylene&action=edit&redlink=1http://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/wiki/Polyaryletherketonehttp://en.wikipedia.org/wiki/PEEKhttp://en.wikipedia.org/wiki/Polyetherimidehttp://en.wikipedia.org/wiki/Polytetrafluoroethylene8/4/2019 Plastic and Construction
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Polystyrene
Yoghurt pots, foam hamburger boxes and egg cartons,
plastic cutlery, protective packaging for electronic goods
and toys. Insulating material in the building and
construction industry.
Unallocated
References
Any other plastics that do not fall into any of the above
categories - for example polycarbonate which is often
used in glazing for the aircraft industry
Manufacturing of Plastic
In the process of manufacturing plastic, there are two major types; manufacturing of
thermoplastics and manufacturing of thermosetting plastics.
Thermoplastics
In the making of thermoplastics, there are several techniques that can be used:
- Extrusion
- Moulding
- Thermoforming
- Recycling
- Coating
Extrusion
Extrusion has 7 types:
- Sheet extrusion
- Co-extrusion
- Profile extrusion
- Cast extrusion
- Pipe extrusion
- Foam extrusion
- Blown film extrusion
Profile extrusion is the process to manufacture plastic products with a continuous cross-
section such as, drinking straws, plastic eves roughing, and a wide variety of other products.
The polymer melts into the hollow mould cavity under high pressure. Steps of the process are
as follows:
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1) Plastic is fed into the extruder machines and being softened by friction rotating screwinside a heated barrel and heat.
2) The softened plastic then is forced out through a die and directly into cool water wherethe product solidifies.
3) It is conveyed onwards into the take-off rollers.4) The die is a metal plate placed at the end of the extruder with a section cut out of its
interior, this cut out, and the speed of the take-off rollers, determines the cross-section
of the product being manufactured.
Typical Materials for Profile Extrusion
- HDPE (High Density Polyethylene)
- LDPE (Low Density Polyethylene)- LLDPE (Linear Low Density
Polyethylene)
- PETG
- Flexible PVC
- Butyrate- Polypropylene
- Polystyrene
- ABS
Moulding
Moulding has 8 types:
- Injection moulding- Blow moulding
- Rotational moulding
- Compression moulding
- Insert moulding- Dip moulding
- Transfer moulding
- Structural foam moulding
There are two types of gas assist injection moulding; Internal Gas Injection (most widely
used) and External Gas Injection (used to improve surface details). Gas-assist injection
moulding is a process that utilizes an inert gas (normally nitrogen) to create one or morehollow channels within an injection-moulded plastic part. Steps of the process are as follows:
1) At the end of the filling stage, the gas (N2) is injected into the still liquid core of themoulding. The gas will follow and create the shape of the product.
2) Gas pressure packs the plastic against the mould surface until the part solidifies.3) The gas is vented to atmosphere or recycled.
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Benefits of Gas Assist Injection Moulding:
Lower cost The use of the gas transmits the pressure
uniformly throughout the moulding.
Elimination of sink marks. Avoidance of plastic packing from the
moulding machine.
Reduce in-mould pressures by up to 70%and therefore reduce press lock forces
enabling larger mouldings on smaller
machines.
Reduce power consumption. Reduce moulded in stress, and therefore
improves dimensional stability with no
distortion.
Typical Materials for Gas Assist Injection Moulding
- Polypropylene (PP)- ABS
- HIPS
- Polycarbonate (PC)- PPC
- Nylon (including glass filled grades).
Thermosetting plastics
In the making of thermosetting plastics, there are several techniques that can be used:
- Pultrusion
- Resin transfer Moulding
- SMC and DMS Moulding
- Other GRP Moulding Techniques
Pultrusion
Pultrusion is a manufacturing method for obtaining high quality composite profiles with
consistently repeatable mechanical properties. It is mainly used for the production of solid or
hollow cross-section products. Pultrusion process can use a wide range of materials to
provide a large type of composite properties. Pultruded products are essentially composed of
high performance fibres such as glass, carbon, or aramide, individually or in combination,
combined with a polymer matrix such as polyester, vinyl-ester, epoxy. Steps of the process
are as follows:
1) Pulling continuous reinforcements through a resin impregnation system. Each fibre is
coated with a specially formulated resin which is to ensure a good condition of the fibre
reinforcement.
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2) Excess resin is then removed to expel any trapped air and to compact the fibres. The
coated fibres are passed through preforming guides to align reinforcement and preform
the part to the desired shape before entering the heated die.
3) The shape and dimensions of the end product are ultimately determined by the die cross
section. The temperature of the die is carefully controlled to ensure that the composite
is fully cured; the rate of reaction is controlled by heating and cooling zones in the die.
4) The fully cured section can be cut to the length according to the size and shape.
Typical Materials for Pultrusion
- Polyester is suitable for most industrial applications.
- Vinyl-ester affords improved corrosion resistance and physical properties.
- Epoxy offers superior thermal stability and corrosion resistance.- Modar improves fire performance and smoke emissions.
- Phenolic maximises fire performance and is offered as an alternative to Modar
Benefits of Pultrusion
Consistent quality Low weight High strength & stiffness Good surface finish Continuous length Excellent corrosion properties Electrical and thermal insulation
Maintenance free Non magnetic attraction Fire retardant properties Excellent creep and fatigue performance Transparent to radio frequencies Pigmentability
Why do we need different kinds of plastics?
Copper, silver and aluminium are all metals, yet each has unique properties. We do not make
a car out of silver or a beer can out of copper because the properties of these metals are not
the best choice for final product. Likewise, while plastics are all related, each resin has
attributes that make it best suited to a particular application. Plastics make this possible
because as a material family they are so versatile.
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Plastics in Building and Construction
From the construction of new homes to the retrofit and renovation of commercial buildings,
and from hospitals to schools, civil engineers, architects and designers rely on plastics to help
maximize energy efficiency, durability and performance. In addition to potentially lightening
a structures environmental footprint, properly installed plastic building products can help
reduce energy and maintenance costs, improve aesthetics and safety over many years.
A one-year study found that the use of plastic building and construction materials saved
467.2 trillion Btu of energy over alternative construction materials. Thats enough energy
saved over the course of a year to meet the average annual energy needs of 4.6 million U.S.
households. Savings vary by material and products. (Source: Franklin Associates, Ltd., U.S.DOE and U.S. Census Bureau).
Below are some examples of plastic building products that promote the efficient use of
energy and other resources:
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1) Plastic Pipes and Fittings
2) Plastic Structural Insulated Panel
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3) Plastic Pipe Radiant Floor Heating
4) Plastic Trims and Wall Coverings
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5) Plastic Decking, Fencing & Railings
6) Plastic Roofing
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Latest Technology of Plastic used in
Construction
We are on the verge of a technology and materials revolution that promises lower
construction costs and a solution to problems such as global warming, waste and housing for
the masses. Construction techniques and materials that have not changed much since the time
of the Romans are all set to change. With the rapid development of technology, new materials
are designed to meet the demand of the construction. Plastic or polymer materials have
developed so much since its invention in the 19th
century. Composite materials which
combine polymer and other building materials such as ceramics, glass and concrete are a
norm and a must in this 21
st
century.
1) TiO2 (Titanium Dioxide) Photocatalytic Membrane
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Applications
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2) ETFE Film
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Applications
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Conclusion
The future of plastic or polymer materials are very promising. In the 20th
century, many
people would not have thought about what plastic can become nowadays. With rapid
development of technology, such as nanotechnology, plastics that once used only for items
that do not require much strength, have changed. Plastics can now become the main structure
of a building, and can be used more dynamically especially in the civil engineering field.
Plastic will truly someday become the main material in our daily life.