Mainly Proccesses to create polymers or plastics

1. Plastic Processes
Alejandro Corredor – alejandrocorredor@usantotomas.edu.co
Student of Engineer Mechanic in Universidad Santo Tomas
Brayan Casas – brayancasas@usantotomas.edu.co
Student of Engineer Mechanic in Universidad Santo Tomas
Diego Gutiérrez – diegogutierrez@usantotomas.edu.co
Student of Engineer Mechanic in Universidad Santo Tomas
Abstract
The plastic play an important role in industry and everyday life of people, this
because of that these materials are rather used for a lot of tasks, from acting as a
container until be part essential of a machine. The plastic are different depending
on your composition, process of manufacture and use. To develop the article, we
will focus mainly on the different processes that produce these materials.
Key Words
Injection, polymers, plastics, extrusion, Moulding.
Introduction
A polymer is a useful chemical made of many repeating units. A polymer can be a
three dimensional network, two-dimensional network or a one-dimensional
network. Repeating units are often made of carbon and hydrogen and sometimes
oxygen, nitrogen, sulfur, chlorine, fluorine, phosphorous, and silicon. Polymers
occur in nature and can be made to serve specific needs. Manufactured polymers
can be three-dimensional networks that do not melt once formed. Such networks
are called thermoset polymers. Epoxy resins used in two-part adhesives are
thermoset plastics. Manufactured polymers can also be one-dimensional chains
that can be melted. These chains are thermoplastic polymers and are also called
linear polymers. Plastic bottles, films, cups, and fibers are thermoplastic plastics.
[1]

2. Some types of plastic or polymers, can you find us in the next table:
Plastic Characteristics / Properties
ABS
(Acrylonitrile-butadiene-
styrene)
Rigid, low-cost thermoplastic, easily machined and thermo-formed.
Acetal Engineering thermoplastic with good strength,wear resistance, and
dimensional stability. More dimensionally stable than nylon under
wet and humid conditions.
Acrylic Clear, transparent,strong,break-resistant thermoplastic with
excellent chemical resistance and weatherability.
CPVC
(Chlorinated PVC)
Thermoplastic with properties similar to PVC, but operated to a 40-
60°F higher temperature.
Fiberglass Thermosetting composite with high strength-to-weight ratio,
excellent dielectric properties and unaffected by corrosion.
Nylon Thermoplastic with excellent impact resistance,ideal for wear
applications such as bearings and gears; Self-lubricating under some
circumstances
PEEK
(Poly-ether-ether-ketone)
Engineering thermoplastic, excellent temperature resistance, suitable
for continuous use above 500°F, excellent flexural and tensile
properties.
PET
(Poly-ethylene-
terephthalate)
Dimensionally stable thermoplastic with superior machining
characteristics compared to acetal.
Phenolic Thermosetting family of plastics with minimal thermal expansion,
high compressive strength,excellent wear and abrasion resistance
and a low coefficient of friction. Used for bearing applications and
molded parts.
Polycarbonate Transparent,tough thermoplastic with high impact strength,excellent
chemical resistance and electrical properties, and good dimensional
stability.
Polypropylene Good chemical resistance combined with low moisture absorption
and excellent electrical properties. Retains strength up to 250°F.
Polysulfone Durable thermoplastic, good electrical properties, operates at
temperatures in excess of 300°F.
Polyurethane Thermoplastic, excellent impact and abrasion resistance,resists
sunlight and weathering.
PTFE
(Poly-tetra-fluoro-ethylene)
Thermoplastic with a low coefficient of friction, withstands heat up
to 500°F, inert to chemicals and solvents,self-lubricating with a low
thermal expansion rate.
PVC
(Poly-vinyl-chloride)
Thermoplastic, resists corrosive solutions and gases both acid and
alkaline, good stiffness.
PVDF
(Poly-vinyl-idene-fluoride)
Thermoplastic, outstanding chemical resistance,excellent substitute
for PVC or polypropylene. Good mechanical strength and dielectric
properties.
Table1.Types of Plastic and its characteristics [2]

3. Development [3]
Exist a lot of types of process to manufacturing the plastics and the polymers, then
going to explain some of the most important and most known process of the
industry around the world.
The information about this process are divide in three parts:
 Processing Thermoplastics
 Processing Thermosets
 Secondary Manufacturing Processes
Processing Thermoplastics
Blown Film
The process involves extrusion of a plastic through a circular die, followed by
"bubble-like" expansion.
Materials Used: Mainly Polyethylenes (HDPE, LDPE and LLDPE) but a wide
variety of other materials can be used as blends with these resins or as single
layers in a multi-layer film structure.
Products Produced: Industry packaging, consumer packaging, laminating film,
barrier film, films for the packaging of medical products, agricultural film.
Extrusion Blow Moulding
The blow moulding machine is based on a standard extruder barrel and screw
assembly to plasticise the polymer. The molten polymer is led through a right angle
and through a die to emerge as a hollow (usually circular) pipe section called a
parison.
Materials Used: Polypropylene (PP), Polyethylene (PE), Polyethylene -
Terephthalate (PET) and Polyvinyl chloride (PVC)
Products Produced: Bottles and containers, automotive fuel tanks, venting ducts,
watering cans and boat fenders.
Extrusion Profiles & Sheet
Is a widely used method of forming plastics materials. The plastic raw material is
both melted and traversed along by the action of heated rotary screws. It is a
continuous process and is thus able to manufacture long lengths of a product. This
is ideal for such applications as pipes and gaskets.

4. Materials Used: HDPE, PVC and and PTFE filled PVC
Products Produced: Land drainage tubing, animal feeding troughs, cable harness,
door seals, light diffusers, electrical conduit and cable protector, rainwater pipes
and guttering, dip tubes, gas pipes, water pipes, soil pipes and window, door and
conservatory sections
Injection Blow Moulding
Injection blow moulding is used for the production of hollow objects in large
quantities. The main applications are bottles, jars and other containers. The
injection blow moulding process produces bottles of superior visual and
dimensional quality compared to extrusion blow moulding.
Materials Used: Polyethylene (Low Density) LDPE, (LLDPE), Polypropylene (PP),
Polyethylene - Terephthalate (PET), Polyvinyl chloride (PVC), Polyethylene (High
Density) HDPE)
Products Produced: Plastic Bottles
Injection Moulding
Injection Moulding, along with extrusion ranks as one of the prime processes for
producing plastics articles. It is a fast process and is used to produce large
numbers of identical items from high precision engineering components to
disposable consumer goods.
Materials Used: Acrylonitrile-Butadiene-Styrene (ABS), Nylon (PA), Polycarbonate
(PC), Polypropylene (PP) and Polystyrene (GPPS)
Products Produced: Power-tool housing, telephone handsets, television cabinets,
electrical switches, dvds, automotive bumpers, automotive dash boards, battery
casings, syringes, drug inhalation units.
Process Cooling
The necessity to cool or chill plastics processing machinery is mainly related to
thermoplastic materials. At room temperature thermoplastic materials are solid. In
order to shape them they must first be heated to their molten temperature. When
molten, they can then be manipulated to a new shape. When formed to their new
shape they must then be cooled to solidify them.

5. Rotational Moulding
Is a process used for producing hollow plastic products. By using additional post-
moulding operations, complex components can be produced enabling the process
to compete effectively with other moulding and extrusion practices.
Rotational moulding differs from other processing methods in that the heating,
melting, shaping, and cooling stages all occur after the polymer is placed in the
mould, therefore no external pressure is applied during forming.
Vacuum Forming
The process involves heating a plastic sheet until soft and then draping it over a
mould. A vacuum is applied sucking the sheet into the mould. The sheet is then
ejected from the mould. In its advanced form, the vacuum forming process utilizes
sophisticated neumatic, hydraulic and heat controls thus enabling higher
production speeds and more detailed vacuum formed applications.
Processing Thermosets
Pultrusion
The pultrusion process starts by pulling/drawing continuous reinforcements through
a resin impregnation system. Each fibre is coated with a specially formulated resin;
the process is controlled to ensure full “wetting out” of the fibre reinforcement.
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. 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.
Resin Transfer Moulding
RTM is a low pressure moulding process, where a mixed resin and catalyst are
injected into a closed mould containing a fibre pack or preform. When the resin has
cured the mould can be opened and the finished component removed.

6. A wide range of resin systems can be used including polyester, vinylester, epoxy,
phenolic and methyl methacylates etc, combined with pigments and fillers including
aluminium trihydrates and calcium carbonates if required.
SMC / DMC Moulding
Manufactures of DMC/BMC compounds is a batch process. The ingredients,
chopped glass fibres, resin, mineral fillers, catalysts and a mould release DMC
Conduit Box agent are loaded into a special mixer. Output from the mixer is in a
flock form which is subsequently extruded in a rope type extrusion.
Manufacture of SMC is a continuous in-line process. The material is sheathed both
top and bottom with a plastic film. A paste is prepared comprising resin, styrene,
heat activating catalysts, inert fillers, release agents and thickeners. The paste is
spread uniformly into an SMC Junction Box the bottom film. Chopped glass fibres
are randomly deposited onto the paste. The top film is introduced and the
sandwich is rolled into a pre-determined thickness. The sheet is allowed to mature
for 48 hours.
Secondary Manufacturing Processing
Welding
Plastic products cannot always be made in one piece. Design and tooling
constraints sometimes make it more economical and/or advantageous to tool the
product as two or more pieces. The choice of which method of joining ultimately
depends on the parts material, geometry and size, process capability, volume and
cycle time desired. Other considerations such as capital costs will have a bearing
on the choice.
Applications: Design and tooling constraints sometimes make it more economical
and/or advantageous to tool the product as two or more pieces. Post moulding
joining of the parts provides a means of achieving an end solution.
Thermoplastic Fabrication
Is a secondary manufacturing process which can be defined as the use and further
modification of primary manufactured sheet, pipe, lining and moulded or formed
profiles using compatible materials and welding methods to produce a final product
or system which can be used in conjunction with or in isolation from non-
thermoplastic materials in the provision of a service, facility, system or process in a
diverse range of Industrial applications.

7. References
 [1] American Chemistry Council, Plastic, The Basics: Polymer Definition and
Properties. https://plastics.americanchemistry.com/Education-
Resources/Plastics-101/The-Basics-Polymer-Definition-and-Properties.html
 [2] Engineering Hand Book, Types of Plastics
http://www.engineershandbook.com/Tables/plasticprops.htm
 [3] British Plastics Federation, Processes to produce plastic
http://www.bpf.co.uk/plastipedia/processes/default.aspx#secondaryprocessi
ngfinishing