A polymer is any of a class of natural or synthetic substances composed of very large molecules, called macromolecules, which are multiples of simpler chemical units called monomers. Polymers make up many of the materials in living organisms and are the basis of many minerals and man-made materials.A polymeric structure is often envisaged as an entangled mass of chain molecules. As the Tg values for many commercial polymers are fairly low, one assumes that thermal agitation causes molecules to wriggle at ambient temperatures.

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Advanced manufacturing
of polymers
Submitted by Nimra Nisa
Roll No. 0053-BS-CHEM-2019
Reg. No. 0117-BS-UON-2019
Course Title Polymer Chemistry
Course Code CHEM-337
Submitted to Professor Hammad Ahmad
Assignment Submission Date
December 20, 2022
University Of Narowal
Department Of Chemistry

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Table Content
Polymers_____________________________________________________________________5
Definition:________________________________________________________________5
Examples: ________________________________________________________________5
Polymer materials_____________________________________________________________5
Processing and manufacturing of polymers ________________________________________5
Polymer processing_________________________________________________________5
Processing ________________________________________________________________5
Manufacturers and processors: ________________________________________________5
Fabricators and finishers: ____________________________________________________5
Advanced manufacturing of polymers ____________________________________________6
Steps of advance manufacturing _______________________________________________6
Categories of manufacturing processes _________________________________________6
Selection of a particular processes _____________________________________________7
Thermoplastic ________________________________________________________________8
Properties of materials ______________________________________________________8
Processing techniques _______________________________________________________8
Examples_________________________________________________________________8
Thermosets___________________________________________________________________8
Processing techniques _______________________________________________________8
Examples: ________________________________________________________________8
Advance techniques for manufacturing of polymers________________________________10
Casting _____________________________________________________________________11
Definition _______________________________________________________________11
Process parameters:________________________________________________________11
Advantages:______________________________________________________________11
Disadvantages: ___________________________________________________________11
Applications:_____________________________________________________________12
Thermoforming______________________________________________________________12
Definition _______________________________________________________________12
Types of thermoforming: ___________________________________________________12
Material type of thermoforming: _____________________________________________13
Disadvantages ____________________________________________________________14
Advantages ______________________________________________________________14
Applications _____________________________________________________________14
Extrusion ___________________________________________________________________14
Definition _______________________________________________________________14
Extrusion process _________________________________________________________14
Process parameter _________________________________________________________15
Advantages ______________________________________________________________15
Disadvantages ____________________________________________________________15
Applications _____________________________________________________________15
Molding ____________________________________________________________________15
Definition _______________________________________________________________15
Types of molding _________________________________________________________16

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Application ______________________________________Error! Bookmark not defined.
Calendaring _________________________________________________________________18
Definition _______________________________________________________________18
Application:______________________________________________________________19
Spinning ____________________________________________________________________19
Definition _______________________________________________________________19
Types of spinning _________________________________________________________19
Application ______________________________________________________________20
Reference ___________________________________________________________________21

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Introduction
The basic understanding of a polymer is necessary then we can try to understand the various
processes that are used to convert the polymers into the tangible or engineering products. Polymers
are the different groups of engineering materials. They are main components of plastic, additives,
rubbers, resins, adhesives, and paints. Polymers are basically the raw materials which we will use
to convert it into a desired product. The processing technique will also affect the properties of the
material. When we try to understand the various processing techniques for polymers and polymer
base composites, we will see that how these parameters, characteristics, factors will influence our
choice of a particular manufacturing process or for a particular processing route for the processing
of polymers and its applications. First, we need to understand that what is this particular type of
polymers. Second, we need to understand that how this particular polymer may have been
manufactured. New innovative technologies are being increasingly incorporated into goods and
manufacturing processes of polymer by advanced manufacturing industries or other polymer
industries. Depending upon our final requirement we will use a different process, but the
fundamental thing will remain same that is heating, forming and finally, cooling. Polymer
materials play a key part in practically every industry, and they are present almost everywhere.
Particularly in recent years, polymeric materials have replaced several items made of wood, glass,
or metal. They have developed into the best substitute for a number of commodities in the
industries of household goods, aerospace, agriculture, and medicine. All of this is because polymer
materials have a variety of unique features, including low cost, chemical inertness, light weight,
insulating property, high toughness, good strength, better elegance, easily moldable character, and
good mechanical strength. Polymer scientists and chemical engineers are enjoying transforming
polymers into products because of all these varied features.

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Advance manufacturing of polymers
Polymers
Definition:
“Any of a group of organic or synthetic compounds that are made up of macromolecules, or very
large molecules, which are just multiples of simpler chemical building blocks (monomers) through
covalent bonds.”
Polymerization is the process through which monomers are converted into polymers. Numerous
substances found in living things, including many minerals and man-made materials, are composed
of polymers.
Examples:
Nylon bearing, plastic bags, polyesters, epoxy glue are some examples of polymers.
Polymer materials
The polymers are the different groups of engineering materials. They are main components of
plastic, additives, rubbers, resins, adhesives and paints. These materials have distinctive
microstructure built from macromolecules networks and chains of carbon or other light elements.
Processing and manufacturing of polymers
Polymer processing
“Engineering activity concerned with operations carried out on polymeric materials or systems to
increase their utility is called polymer processing.”
Processing
“A systematic series of mechanized or chemical operations that are performed in order to produce
something.”
Manufacturers and processors:
There are more than 200 significant producers of specialty and over 200 producers of general-
purpose polymers. Although the majority of businesses buy the essential polymeric materials from
other businesses, some firms make their own polymeric materials for later processing.
The usage of certain polymers, such nylons and polycarbonates, or a particular processing method,
including coatings, films, sheets, laminates, bulk molded, and reinforced plastics, are areas of
specialization for processors.
Fabricators and finishers:
The vast majority of businesses are engaged in the fabrication and finishing of polymers, i.e., the
creation of finished goods for commercial and domestic use. Chemical engineers and polymer
chemists take great joy in turning polymers into usable goods because of all these varied features.
Polymer fabrication is the method in question. So, Construction of goods utilizing a combination
of typically standardized parts and one or more distinct procedures is known as fabrication.

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Primary categories for fabrication
There are the three primary categories that make up fabrication.
➢ Machining
➢ Shaping
➢ Fashioning
Grinding, sawing, screwing, and other processes are all part of machining. Molding is a form of
forming. Plus, other ways to shape and attach using tools like welding, glue, and screws.
Cutting, stitching, sheeting, and sealing are all aspects of fashioning. Sequences of fabrication vary
depending on the polymeric material and desired final product.
Advanced manufacturing of polymers
When new technology is used in manufacturing to enhance goods or procedures of polymers, it is
referred to as advanced, innovative, or cutting-edge technology. New innovative technologies are
being increasingly incorporated into goods and manufacturing processes of polymer by advanced
manufacturing industries or other polymer industries.
Steps of advance manufacturing
An ever-increasing variety of materials are now available, each having its own
➢ Characteristics
➢ Applications
➢ Advantages
➢ Limitations
Select the optimal material according to the design and in-service requirements. Now as per the
design of the product we will choose that which material satisfy our requirements and second one
is also the in service used means that when the product will be used, what type of conditions it will
have to sustain or what type of environment it has to sustain or what type of loads that are going
to act on that particular product.
So, the selection of polymers as an engineering material, will depends upon below characteristics
and justification that need to develop for proposing the use of polymers.
➢ Mechanical properties (hardness, strength)
➢ Physical properties (density, melting points)
➢ Chemical properties (corrosion, toxicity)
➢ Manufacturing properties (machinability)
➢ Cost and availability
➢ Service life
➢ Recycling and waste disposable
Categories of manufacturing processes
All the manufacturing processes can be put into basic six categories according to the nature:
➢ Primary forming processes (additive)
➢ Material removal or machining (subtractive)
➢ Deforming processes (formative)
➢ Joining or fabrication or consolidation (assembling)
➢ Finishing and surface treatment processes

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➢ Bulk property enhancing processes (heat treatment)
Now for specifically polymers primary forming processes are very important because it give a
shape to the products, compression molding, injection molding, extrusion, thermoforming, all
these processes rotational molding are fall under the primary forming processes. Some time we
need to make a hole in a polymer plate or in a plastic plate. Sometime we may be required to cut
a screw inside the polymers or threads inside the polymers plates.so that will fall under the material
removal or machining processes. Deforming processes not very common in case of polymers
because we mold the things in the primary forming stage only, we melt the plastic and give it a
desired shape that we consider in the primary forming processes. but sometime we will made long
tubes of polymers that we can say that fall under the deforming. When joining or fabrication it is
very difficult to join the polymers parts together because if permanently join the polymers’ part,
then need to do adhesive joining which is also a challenging task. So, we will see the joining
behavior of the polymers, but the joining can be adhesive joining, it can be a mechanical fastening.
So, those are the processes specially for polymers and then finishing and surface treatment
processing may be in terms of plastic can be some specific coating on the surface. And finally,
the bulk property enhancing processes such as heat treatment which is very uncommon in case of
polymers.so, these are the processes which can be done on the polymers. (Jr., 2017)
Selection of a particular processes
The properties or selection of a particular processes will depend upon the
➢ Properties of the raw materials (hardness, melting points)
➢ Size of the final product because this is a smaller product, if we have to make a very big
product the process has to be different.
➢ Shape of the final product because if the shape is simple then we will select one process is
the shape is complicated then we will go for a different process.
➢ Production volume because how many products you want to make you want to make
hundred products or you want to make one million products. So, we will select the process
accordingly.
➢ Quality requirements of the final product, what type of surface finish require, what type of
surface characteristics require that will dictate the selection of the manufacturing process.
➢ In-service requirements of the final products because the processing technique will also
affect the properties of the material. And the properties will further affect its behavior once
the product is put into service.
When we try to understand the various processing techniques for polymers and polymer base
composites, we will see that how these parameters, characteristics, factors will influence our
choice of a particular manufacturing process or for a particular processing route for the processing
of polymers.
The basic understanding of a polymer is necessary then we can try to understand the various
processes that are used to convert the polymers into the tangible or engineering products. So,
polymers are basically the raw materials which we will use to convert it into a desired product.
➢ First, we need to understand that what is this particular type of polymers.
➢ Second, we need to understand that how this particular polymer may have been manufactured.

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Thermoplastic
“A material that cures reversibly and softens when heated above the glass transition temperature
or melting point and becomes hard after cooling is called thermoplastic.”
Thermoplastic have a linear and branched molecular structure.
Properties of materials
The notable properties of the thermoplastic materials are:
➢ High strength and toughness
➢ Better hardness
➢ Chemical resistance
➢ Durability
➢ Self-lubrication properties, transparency and water proofing
Processing techniques for thermoplastic
Thermoplastic can be processed by heating up to glass transition temperature and formed into the
desired shape with the application of pressure. So, the basic fundamental principle remains same
that is heating forming and finally, applying the pressure and the last part is allowing it to cool and
solidify finally get our product.
Examples
Thermoforming, compression molding, injection molding, blow molding and extrusion molding
are some techniques processing for thermoplastics. So, there are number of processing which can
be used for processing of thermoplastics.
Thermosets
“The materials which cure irreversibly and become permanently hard and rigid after curing are
called thermosets.”
Thermosets plastic cannot be re-melted, continued heating for a long time leads to degradation or
decomposition. Thermosets have three-dimensional network of covalent intermolecular bonds
(cross-linked structures).
Processing techniques for thermosets:
Thermosets can be processed in two steps, first it can be melted and then poured into the mold to
make a desired shape.
Examples:
Casting and resin transfer molding. So basically, our thermoset is available most of the times in
the gel form. We can change its viscosity by adding the hardener and the other additives and
finally, we can pour it into the desired mold. Mold will be the exact replica of the final product
that we want and allow it to solidify allow it to cool and after may be the predefined time period
we will get the final product when the thermoset has cured it has become solid, we can take out
the product.
So, the broad classification of the processes for polymers can be based on the type of end product
that we want to make and based on the type of raw material that we are using. So, the raw material
can be thermoplastic and a thermosetting polymer. (Jr., 2017)

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Compare that the stress strain behavior with the stress behavior of a polymers then in the diagram
after necking there is a long zone of plastic deformation and then there is a fracture point and this
type of behavior may be observed in case of thermoplastic and thermoset type of polymer, the
properties will or this behavior will entirely change. So, within the polymer family also the stress
strain behavior will keep on changing depending upon the grade of the polymer, depending upon
the type of polymers, depending upon the molecular arrangement inside the polymer the stress
strain behavior change.
So, it will take a lot of strain before it finally, fills and the fracture point is shown here. Once you
do the tensile testing and the flexural testing of the polymers or the polymers specimen you will
get certain values. So, the flexural strength of the polymers may vary from 40 to 175MPa. So, the
polymers are the very big family. So, there is a lot of range that is available and why this range is
possible because of the difference in the materials due to the different properties for thermoset and
thermoplastic. (Pascault & Williams, 2013)
Similarly, the tensile strength of polymers varies from as 11.7 megapascal to as high as 185MPa.
So therefore, it is important to understand that the mechanical properties are different, the chemical
nature of the different types of polymers is different and therefore, the processing techniques
required for different types of polymers are different. because of different in the properties, the
chemical nature of different types of polymers or variation in the chemical nature of different types
of polymers the techniques that employed for converting these polymers into products vary and
they vary significantly. We may use different techniques for thermoplastic and thermosetting.
Manufacture of a particular product may require more than one forming process.
A crucial feature of most polymer processes is the preparation of the polymeric material in a
appropriately softened state to suit the forming stage. Usually, the softened state is achieved by
heating the polymer.
Setting the shape is achieved by either cooling or carrying out a chemical process (crosslinking)
to achieve the necessary dimensional stability.
Polymer manufacturing processes can be divided into
➢ Continuous processes
➢ Batch processes

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In continuous process where raw material is fed in continuously and the product flow appears
continuously e.g., extrusion, there is more efficient use of energy and it is easier to maintain a
consistent quality.
For batch or cyclic processes, such as molding processes, there is a higher probability of batch-to-
batch variation and lower efficiency due to unproductive parts of the cycle.
The chemical nature of the polymer is affecting its mechanical behavior.
➢ Polymers are synthetic and semi-synthetic organic solids and can be easily processed.
➢ The processing stages of polymers are heating, forming and cooling in continuous or
repeated cycles.
➢ The manufacturing processes of polymer products depends on the shape of the final product
and the types of the plastic material being used.
Now depending upon the requirement, we may have different types of processes, if we want to
make a plastic bottle the process will be different, if we want to make a polymer handle, plastic
handle the process will be different, if we want to make a specific shape that has to be used in a
toy for children the process will be different. But, depending upon our final requirement we will
use a different process, but the fundamental thing will remain same that is heating, forming and
finally, cooling. (Pascault & Williams, 2013)
Advance techniques for manufacturing of polymers
There are various polymer manufacturing methods that go into turning raw polymers into finished
goods. No matter the industry, polymer materials play a significant role; polymer-based materials
can be found almost everywhere. Polymeric materials, in particular in recent years, have benefitted
society and replaced many objects made of wood, glass, or metal. They have evolved into the best
replacement for a variety of products in the fields of medicine, agriculture, aerospace, automobiles,
and household goods. All of this is because polymer materials have a variety of unique features,
including low cost, chemical inertness, light weight, insulating property, high toughness, good
strength, better elegance, easily moldable character, and good mechanical strength. Polymer
scientists and chemical engineers are enjoying transforming polymers into products because of all
these varied features. (Jr., 2017)
Techniques for polymers are as following:
➢ Casting
➢ Extrusion
➢ Thermoforming
➢ Molding
• Injection molding
• Compression molding
• Reaction injection molding
• Blow molding
• Extrusion molding
➢ Spinning
• Wet spinning
• Electrospinning

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Casting
Definition
Casting is the process of manufacturing a plastic part into a mold. Plastic material is melted and it
is poured into the mold cavity. So here the word melted is slightly ambiguous because if the
thermoset is available in the gel form, we will directly use that and pour that into our mold cavity
with the hardener and allow it to solid after solidification it will take the desired shape.
As the plastic cools, it will solidify into the desired shape and part is ejected.
Process parameters:
➢ Melting temperature of polymer
➢ Pouring temperature
➢ Cooling rates
Figure: Casting processes
The types of materials that can be used for casting process is the thermosets are majorly used for
such type of process. So, the thermosets such as polyester, urethanes, phenolics and epoxy and
thermoplastic material such as acrylics and nylons can be used for casting.
Advantages:
➢ We have not much sophisticated instrumentation tools or fixtures are required we simply
required a mold which is the exact replica of our final product.
➢ Low initial investment cost, flexible parts can be made dimensional stability will be the
exactly depending upon the type of mold.
➢ High production rate. So, we can make number of products continuously.
Disadvantages:
It is a manual process because we are not using any machines, complex shapes because the heated
plastic has to flow in the mold cavity. If the shape is very complex, we are not applying any external
pressure to force this plastic or the polymer into the mold cavity. So, it may not its own flow into
the mold cavity and therefore, the complexity of shape is of major limitation in case of the casting
process.

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Applications:
It is used to produce collectible and customized toys like designer toys, garage kits, ball jointed
dolls, sheets, wheels, either individual parts or entire model of objects like trains, aircraft, boat and
ships.
One of the most primitive and most of the application that you see are not very high-end
applications and as the process has no machine control so is used for low and a non-structural and
very simple products can be made by using this process of casting.
Thermoforming
Definition
Thermoforming is the plastic processing techniques in which the thermoplastic sheets are formed
with the application of heat and pressure in a mold. So, the pressure can be in the form of
mechanical, pneumatic or air pressure, it can be applied even can vacuum and based on the method
which we are applying the pressure.
Types of thermoforming
Then thermoforming processes can be divided into different types:
➢ Vacuum thermoforming
➢ Pressure thermoforming
➢ Match die forming
Vacuum thermoforming process
In this method, the heated thermoplastic sheet is shaped into the required shape using vacuum
pressure. The thermoplastic sheet is put in place and secured with a clamping unit on the mold
surface. After heating the sheet until it softens, a brief vacuum application is required. To swiftly
remove the air from between the mold cavity and the sheet, a surge tank is employed. The sheet
takes on the shape of the mold cavity when the vacuum is produced. The produced part is allowed
to cool before being removed from the mold chamber. The diagram in figure depicts the vacuum
forming process.
Figure: Vacuum forming process
Pressure thermoforming process
When it comes to pressure forming, the procedure is very similar to vacuum foaming. In contrast
to vacuum formation, a higher air pressure is needed. Once the heated plastic sheet is in position
on the mold surface, air pressure is swiftly added above the sheet. The softening sheet and the

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pressure box are where the high pressure is created. High pressure makes it possible for the heated
plastic sheet to quickly deform into the mold cavity. The produced sheet is kept in the mold cavity
for a brief period of cooling. This causes the produced portion to solidify and be ejected from the
mold chamber.
Figure: pressure thermoforming processes
Match die forming
Mechanical forming is another name for matched die forming. Die and punch are the two
components that make up a mold. The use of heat causes the thermoplastic sheet to warm up and
soften. A preheated sheet is inserted into the die, and the sheet is punched through. By utilizing a
vacuum pump to remove the air from the gap between the die and sheet, the sheet can take the
shape of the mold. After cooling, the formed portion is removed from the mold.
Figure: mechanical thermoforming processes
Material type of thermoforming:
Different types of thermoplastics which can be processed using thermoforming process are:
➢ Acrylic (PMMA)
➢ Low Density Polyethylene (LDPE)
➢ High Density Polyethylene (HDPE)
➢ Polyvinyl Chloride (PVC)
➢ Acrylonitrile Butadiene Styrene (ABS)
➢ Cellulose Acetate
➢ Polypropylene (PP)
➢ Polystyrene (PS)

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Disadvantages:
➢ Poorly finished surfaces
➢ The thickness of a part's walls may not be uniform.
➢ You must trim each component.
➢ It's difficult to form ribs and bosses.
➢ Materials can only be utilized in a certain amount.
➢ There is no way to create really thick plastic sheets.
Advantages:
➢ Very flexible to design requirements
➢ Development of prototypes quickly Low setup expenses
➢ low manufacturing cost.
Applications:
A wide range of items, including food packaging, trays, building materials, aeroplane windscreens,
and automotive and aerospace components, utilize the thermoforming process. Thick gauge
sections are utilized as decorative surfaces on long-lasting constructions including vehicles,
medical equipment, material handling equipment, electrical and electronic equipment, spas and
shower enclosures, car door and dash panels.
Extrusion
Definition
Extrusion is a manufacturing method with high output. Heat is applied to the plastic material until
it melts, then it is extruded through a die into the required shape. The burel contains a revolving
cylindrical screw that pushes molten plastic material through a die. Mechanical energy produced
by heaters positioned along the barrel's length and by spinning screws. The liquid polymer is then
pressed into a die, which gives it a shape that will become solid upon cooling.
Extrusion process:
Plastic pellets or granules are gravity fed into the barrel of the extruder from a top-mounted hopper.
The hopper can be used to combine additives like colorants and UV inhibitors. The revolving
screw makes touch with the plastic material that enters through the feed mouth. The plastic beads
are pushed forward into the barrel by the rotating screw as the barrel is heated by heating sources
to the melting point of the plastic. The melting zone has fully melted the plastic substance. The
barrels inside temperature is controlled by a thermostat. It is important to avoid overheating plastic
because this can weaken the material's characteristics. The barrel's temperature is kept constant
throughout the procedure using a cooling fan or a water-cooling system. To get rid of any
contaminants, the molten plastic flows through a screen pack at the head of the barrel after leaving
the screw. A breaker plate serves as reinforcement for the screens. Additionally, the breaker plate
assembly works to build up back pressure inside the barrel. Back pressure aids in the barrel's
correct mixing and homogeneous melting of the molten plastic material. Melting plastic flows into
the die after going through the breaker plate. Unwanted tensions would be created in the plastic
product by an uneven flow of molten plastic. After the molten plastic has solidified, these forces
may result in wrapping. Due to their excellent thermal insulating properties, plastics is very

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difficult to cool quickly. The cooling of plastic product is achieved by pulling through a set of
cooling rolls.
Process parameters:
➢ Melting temperature of plastic
➢ Speed of screw
➢ Extrusion pressure required
➢ Type of die used
➢ Cooling medium
Figure: Extrusion process
Advantages:
➢ minimal cost per part
➢ Operational adaptability
➢ increased production rates
➢ Raw materials come in a variety of forms.
Disadvantages
➢ Size variations of the product
➢ One sort of cross section can only be obtained at a time, which places constraints on the
products.
➢ Expensive setup at first
Applications
Used extensively in the manufacture of tubes and hollow pipes, with aluminum extrusion being
the primary method used in structural work, as well as the manufacture of frames, doors, windows,
and other items for the automotive, aerospace industries, plastic films and sheets, thermoplastic
coatings, and wire insulation are all products of extrusion.
Molding
Definition
A molding process uses pressure and heat to fill the cavity of a mold, a rigid frame also known as
a matrix. It is crucial to prepare three-dimensional articles or shaped objects using the appropriate
molds. Metal or glass and different polymers are used to create the molds. After the three-
dimensional items have fully cured, the mold-releasing agent is frequently employed to remove
them from the molds.

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Types of molding
Compression molding process
To create items from thermosetting materials like resin, this molding procedure is frequently
utilized. One half of the mold is upper, and the other half is lower. Typically, the upper half has a
projection that fits into the bottom half's cavity when the mold is closed. The lower half typically
has a cavity. The molded device's shape is determined by the space between the top projected half
and the cavity in the bottom one.
The polymer material is forced between the mold's stationary and movable parts during the
compression molding process. When the mold is closed, heat and pressure are applied
simultaneously, causing the material to transform into plastic and flow into the mold to fill it. On
the other hand, the pressure and temperature that are required rely greatly on the thermal and
rheological characteristics of the polymer. The extra polymer material that is forced out of the
cavity as a thin film under high pressure is referred to as the "flash." The molds are kept together
until every bit of resin has hardened, which could take anywhere from 30 seconds to several
minutes. The item is then released after opening the mold. The molds in this technique are often
constructed of metal that has been chromium-plated. Typically, a temperature of 150 °C and a
pressure of 200 psi are used.
Figure: compassion molding process
Application
Compression molding is used for manufacturing; electrical and electronic equipment, brush and
mirror handles, trays, cookware knobs, cooking utensils, dinnerware, appliances housings, aircraft
main power terminal housing, pot handles and large container.
Injection molding
It is a quick method for creating both thermoplastic and thermosetting polymers. The polymer is
fed into a hopper and driven into a horizontal cylinder where it is softened by electrical heating
plates. The polymer is in the form of powder or liquid resin. Through a hydraulically powered
piston, pressure is delivered to the molten material into a mold that is attached to the end of the
cylinder. A tool known as a torpedo aid in accelerating the plastic material uniformly across the
hot cylinder's interior wall when it passes through a hot zone. As a result, it can guarantee even
heating of the material.
The cylinder's molten material is then pumped into the mold cavity using a nozzle. After cooling
or curing, the polymer solidifies, allowing the product of a certain shape to be removed. The pattern

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is repeated, and since it typically only lasts 10 to 30 seconds, the method is excellent for mass
production.
Figure: injection molding
Applications:
The injection molding process can be used to manufacture thin-walled plastic housing products
which require many ribs and bosses on the interior surfaces. These housings are used in a variety
of products including household appliances, electronics, power tools and as automatic dashboards
Reaction injection molding
This form of injection molding is more recent. Two monomers (resins) are injected collectively
into the mold during this procedure. The two resins react chemically just prior to being placed
inside the mold. A polymer can be created in a shorter amount of time at low temperatures without
needing additional heat for molding. This molding technique is used to create human body
components.
Figure: reaction injection molding

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Blow molding
It is affordable and just requires a simple process, blow molding actually primarily belongs to the
glass sector. However, it has been adapted for use in the polymer business. In this technique, a
parison-shaped piece of molten polymer tube is properly inserted from an extruder between two
mold halves. A blowing pin is placed at one end of the parison after the two halves of the mold are
closed, pinching or closing the other end. Then, a blowing pin is used to inject compressed gas
into a partner at a pressure of roughly 2 to 100 psi. The heated parison is inflated like a balloon
and continues to grow until it comes into close contact with the inside surface of the hollow mold,
which is relatively cool. The parison eventually takes on the shape of the mold's hollow cavity
when put under pressure. The hard object is removed by opening the mold once the mold has had
time to cool. In order to obtain more objects, the operation is repeated.
Figure: blow molding process
Applications:
Different types of plastic products can be manufactured by this process such as bottles in different
shapes and sizes, jars and containers, ducting, fluid oil tanks, mugs and toys.
Calendaring
Definition
It is a crucial process for producing film and sheet. The plastic compound is run through a series
of heated rollers in this procedure. By passing through cold rollers, the sheet that emerges from
the rollers is chilled. Finally, the sheets are wrapped into rolls. However, by continuing to squeeze
and adjusting the speed of the finishing rolls, the thickness is managed.
Figure: calendaring process

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Application:
Coated papers are calendared to provide a smooth, glossy finish. Calendaring is also widely used
in the manufacture of textile fabrics, coated fabrics, and plastic sheeting to provide the desired
surface finish and texture.
Spinning
Definition
Until recently, the spinning technique was only used in the textile industry to make fibres. It is
now expanded to include the manufacturing of fine polymeric fibres. Numerous biological
applications for these tiny fibres exist, including tissue engineering, medication release, wound
dressing, enzyme immobilization, biosensors, tooth restoration, and medical implants. Three
methods in particular can be used to manufacture fibres through the spinning process.
Types of spinning
Wet spinning
This technique involves infusing a viscous polymer solution into a coagulation bath that contains
a nonsolvent, followed by extruding the solution through a continuous filament. The viscous
solution solidifies or precipitates as a fibre during the nonsolvent process, and the fibre is then
wrapped up on a spool. Because of the discontinuity in the jet, it is possible for droplets to form
during the wet spinning procedure rather than a continuous filament. By making the polymer
solution viscous, this can be avoided.
On a large scale, the viscous polymer solution is pushed into a nonsolvent-containing coagulation
bath using a motor-driven syringe pump. Precipitates and is easily removed and coiled up with a
roller. In a different process that is applied on a large scale, the polymer solution is first forced to
form the filaments by flowing through a spinneret, which is a specially made metal plate with a
number of drilled superfine holes. In a coagulation bath with a nonsolvent, the polymer solution
was expelled as tiny fibres. The fibres produced can be cleaned, finished, and then wrapped up
using a roller. (Kariduraganavar et al., 2014)
Figure: wet spinning process
Electric spinning
Numerous biomedical sectors are utilizing the most current advances in nanotechnology,
particularly in the creation of scaffolds for tissue engineering and medication delivery. The

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discovery of biological replacements that preserve, restore, or enhance tissue functions has
benefited greatly from tissue engineering. This is a result of the electrospinning technique's
production of nanofibers. Therefore, in the age of current modern technology, electrospinning is a
crucial technique.
In this method, an appropriate polymer solution is chosen to pull fine (usually micro- to nanoscale)
fibres using an electrical charge. This technique makes it feasible to create semicrystalline polymer
fibres such as polyethylene, PET, and polypropylene, which would otherwise be impossible or
challenging to create using other techniques.
The configuration, which consists of a syringe, high voltage source, and the collector, is identical
to that used in conventional spinning processes. The liquid body becomes charged when a high
enough voltage is given to a syringe needle. Electrostatic repulsion then works to counteract the
surface tension and expand the droplet. A stream of polymer liquid suddenly emerges from the
surface at a critical point. Due to the liquid's high molecular cohesion, stream breakage is
prevented, and a charged liquid jet is created.
Figure: electric spinning process
Advantages
➢ It is suitable for heat-sensitive polymer
➢ Higher spinning speeds can be easily achieved
➢ A moderate concentration of polymer is required.
➢ Direct and simple process.
➢ High production speed.
➢ Low investment cost.
➢ No environmental pollution.
Disadvantages
➢ It is suitable for thermoplastic fiber.
➢ Flammable solvent hazards.
➢ Solvent recovery is required.
➢ Maximum strength can’t be achieved easily.
➢ The heat of the input is high.

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References:
Jr., C. E. C. (2017). Introduction to Polymer Chemistry ( Fourth Edition ).
Kariduraganavar, M. Y., Kittur, A. A., & Kamble, R. R. (2014). Polymer synthesis and processing.
In Natural and synthetic biomedical polymers (pp. 1-31). Elsevier.
Pascault, J. P., & Williams, R. J. (2013). Thermosetting polymers. Handbook of Polymer Synthesis,
Characterization, and Processing, 519-533.
Jasiuk, Iwona, et al. "An overview on additive manufacturing of polymers." Jom 70.3 (2018): 275-
283.
Donald G. Baird, Dimitris I. Collias . (1998). Polymer Porcessing: principle and design