This document provides information about plastic and specifically polymethyl methacrylate (PMMA) or acrylic plastic. It discusses that plastics are polymers made from petroleum that can be molded into various shapes. It then describes the two main types of plastics - thermoplastics and thermoset plastics - and provides examples of each. The document also outlines various properties and uses of plastics in general and PMMA specifically, including in construction, lighting, automotive, electronics, furniture and more. However, it notes that PMMA has limitations such as poor impact resistance and chemical resistance and may cause side effects if used in medical applications.
2. What is plastic?
• Polymers are long chains of molecules (mostly
carbon) bonded to each other. Most of the
materials that are called plastics are polymers.
• Plastic is a specific type of polymer that can
change its shape. Plastics are made from
petroleum.
• Many things around us are made of plastics. For
example: Polythene, toys, bags, chairs, table,
boxes etc. There are some well-known plastics
around us. They are polypropylene (chair, tables
etc), polystyrene (plastic spoons & forks, cups
etc), polyamide (usually known as nylon) used in
toothbrushes, car-parts etc.
• Polythene is a very commonly used plastic,
mostly in the form of carry bags.
Types of plastic
• There are two major types of plastics based on
their heat management nature. They are:
1. Thermosetting Plastics
• The plastics which when cooled and hardened
once lose their ability to change dimensions on
heating are known as thermosetting plastics.
These plastics retain their shapes and can not
return to their original form i.e they are
irreversible.
• This type of plastic is used for making auto parts,
aircraft parts etc. Bakelite and melamine are
some examples of thermosetting plastics.
• Once they are given a shape and cooled, they
cannot be melted again to form a new shape.
Plastic
3. 2. Thermoplastic
• Plastics that soften upon heating and return to
their original form are called thermoplastics. They
can be moulded and remoulded again and again.
• Thermoplastics are used for low-stress
applications such as plastic bags or high-stress
mechanical parts. This type of plastic is first
heated, and then cooled to get the final shape.
• The material can be reheated, reshaped and
cooled repeatedly i.e thermoplastics are
recyclable. They do not lose their dimension
changing ability.
• For example: Polythene and poly ethylene are
the most commonly used thermoplastics in our
daily life.
Plastic recycling
• Recycling is a difficult process which involves
many processing steps. Before recycling, we
have to collect the plastic material that is to be
recycled i.e waste or scrap plastic.
• Then, every plastic item is separated according
to its type because different types of plastics
must be processed in different ways and not all
plastics are recyclable.
• After this, washing has to be done to remove
impurities that enhance the quality of the
manufactured product.
• Cleaned and dried plastic items are then melted
at a regulated temperature and moulded into a
new shape.
• This reduces high rates of polluting of land and
water bodies.
• At the same time, recycling puts less pressure
on virgin materials to produce new plastic
products.
4. Advantages of plastic
• Plastics of the following advantages over metals:
1. Plastics are highly flexible as compared to
metals. For industries that need designing
options, geometry and different kinds of textures,
plastics are going to be the most suited
materials.
2. Plastics are cheaper as compared to metals. The
manufacturing of plastic parts is budget-friendly.
3. Plastics are highly durable and can last for an
indefinitely long period of time. Metals, on the
other hand, are much more prone to chemical
and weather susceptibilities.
4. The specific gravity of plastic is much lower
making it an extremely lightweight material.
5. Manufacturing of plastic is a faster process as
compared to metals.
Uses of plastic
• Plastics are highly durable, lightweight and most
importantly can be moulded into any form or
shape. These properties account for the largest
usage of plastics. Plastics are extremely versatile
materials and can be used for a wide variety of
purposes. Some usage of plastics are given
below:
1. The ability to be moulded makes plastic an ideal
packaging material. Plastics in packaging help to
keep foods safe and fresh.
2. Being durable and lightweight, plastics have
helped in the electronic field. From computers
and cell phones to television and microwave,
almost all appliances around us make some use
of plastic.
5. 3. Plastics are used to make safety gear like
helmets, goggles etc. Plastics are used in the
construction industry due to their low maintenance
durability and high.
4. Plastic is strong and lightweight, that is why it is
useful in making toys, electrical switches and other
household products.
5. Being non-reactive with air and water, plastic is
used to store water in plastic bottles and other
chemicals laboratories. in chemical.
6. Plastic is a poor conductor of electricity and heat.
Its insulation property is used for coating the electric
wire and to make handles of cooking utensils and
various household products.
Properties of plastic
• The following properties are common with most
of the plastics.
1. They are light in weight.
2. They have good resistance to most of the
chemical.
3. They have high electrical strength.
4. They have good corrossive resistance.
5. Plastics can be moulded to any desired shape
and size.
6. They can be made transperent or color.
7. They are cheap compared to metals.
8. All operations like drilling ,sawing, punching can
be done on plastics.
9. Painting and polishing is not necessary.
10.The plastics posses excellent electric insulating
properties.
11.The plastics, have low specific gravity, the
average being 1.3 to 1.40.
6. Acrylic plastic (PMMA)
What is acrylic plastic (PMMA)?
• In the plastics industry most acrylics are
polymers of methyl methacrylate (PMMA).
• Acrylics may be in the form of molding powders
or casting syrups, and are noted for their
exceptional clarity and optical properties.
• Acrylics are widely used in lighting fixtures
because they are slow-burning or even self-
extinguishing, and they do not produce harmful
smoke or gases in the presence of flame.
• The most important properties for acrylic
(PMMA) are itsoptical clarity, low UV sensitivity,
and overall weather resistance. Acrylic is often
used as a glass substitute.
How PMMA is made?
• Poly(methylmethacrylate) is produced by free‐radical
polymerizationof methyl methacrylate in mass (when
it is in sheet form) or suspension polymerization.
PMMA Processing Conditions
• PMMA is suitable for processing by injection
molding, extrusion, extrusion blow molding
(impact modified acrylics only), thermoforming
and casting.
• Pre-drying is not necessary if a vented cylinder is
used but if a normal cylinder is used then PMMA
must be processed dry and it is advisable to pre-
dry the granules for up to 8 hours at 70-100°C.
Surface defects and blisters will form if damp
granules are processed.
7. Injection Molding
• Melt temperature : 200-250°C
• Mold temperature : 40-80°C
• High injection pressures are needed because of
poor flow properties and it may be necessary to
inject slowly to get the correct flow.
• Internal stresses can be eliminated by heating at
80°C
Extrusion
• Extrusion temperature : 180-250°C
• A degassing screw with an L/D ratio of 20-30 is
recommended.
• PMMA can be welded by all the plastics welding
processes such as hot‐blade, hot‐gas, ultrasonic
or spin welding.
• Due to its transparency and stiffness, PMMA is
also used as 3D Printing material but it requires
slightly high temperature and a bit more prone to
wrap as compared to PLA. PMMA filaments are
available in wide array of colors.
What are the uses of PMMA?
• Due to its transparent properties, lightweight and
superior toughness compared to glass. It was
extensively used make aircraft windshields,
canopies and gun turrets. After this several other
commercial applications were developed for
PMMA such as glass roofing, façade design,
advertising, automotive headlamps, etc.
Architecture and Construction
• Thanks to its excellent impact and UV resistance,
PMM is widely used in window and door profiles,
canopies, panels, façade design, etc. It also
facilitates light transmission and provides good
heat insulation, hence a suitable choice of
building green houses. PMMA is also used to
build aquariums and marine centers.
8. Lighting
• PMMA sheets are used for designing LED lights where
it helps maximize light emitting potential.It is also
used for construction of lampsthanks to its
transparency and opticalproperties.
Automotive and Transportation
• In vehicles, PMMA sheets are used in car windows,
motorcycle windshields, interiorand exterior panels,
fenders etc. Also colored acrylic sheets are used in car
indicatorlight covers, interiorlight covers etc. It is
also used for windowsof a ship (Salt resistance) and
aviationpurposes.
• PMMA also open new design possibilitiesfor
car manufacturers thanks to its pleasantacoustic
properties, outstandingformability and excellent
surface hardness.
9. Electronics
• Due to its excellent optical clarity, high light
transmission and scratch resistance, PMMA is
widely used in LCD/LED tv screens, laptops,
smartphones display as well as electronic
equipment displays. PMMA also finds used in
solar panels as cover materials thanks to its
excellent UV resistance and excellent light
transmission allowing high energy conversion
efficiencies.
Medical and Healthcare
• PMMA is a high purity and easy-to-clean
material and hence used to fabricate incubators,
drug testing devices, storage cabinets in
hospitals and research labs. Also, due to its high
bio-compatibility, PMMA is also applied as dental
cavity fillings and bone cement.
Furniture
• PMMA offers exception properties such as
transparency, toughness and aesthetics to
produce chairs, tables, kitchen cabinets, bowls,
table mats etc. in any shape, color or finishes.
10. Properties of PMMA
1. Transmittance
• PMMA (Acrylic) polymer has a Refractive Index
of 1.49 and hence offers high light transmittance.
PMMA grades allow 92% of light to pass
through it, which is more than glass or other
plastics. These plastic materials can easily be
thermoformed without any loss in optical clarity.
As compared to polystyrene and polyethylene,
PMMA is recommended for most outdoor
application thanks to its environmental stability.
2. Surface Hardness
• PMMA is a tough, durable and lightweight
thermoplastic. The density of acrylic ranges
between 1.17-1.20 g/cm3 which is half less than
that of glass. It has excellent scratch
resistance when compared to other transparent
polymers like Polycarbonate, however less than
glass. It exhibits low moisture and water
absorbing capacity, due to which products made
have good dimensional stability.
3. UV Stability
• PMMA has high resistance to UV light and
weathering. Most commercial acrylic polymers are
UV stabilized for good resistance to prolonged
exposure to sunlight as its mechanical and optical
properties fairly vary under these conditions,
Hence, PMMA is suitable for outdoor applications
intended for long-term open-air exposure.
4. Chemical Resistance
• Acrylics are unaffected by aqueous solutions of
most laboratory chemicals, by detergents,
cleaners, dilute inorganic acids, alkalies, and
aliphatic hydrocarbons. However, acrylics are NOT
recommended for use with chlorinated or aromatic
hydrocarbons, esters, or ketones.
11. Limitations of PMMA
• Poor impact resistance
• Limited heat resistance (80°C)
• Limited chemical resistance, prone to attack by
organic solvents
• Poor wear and abrasion resistance
• Cracking under load possible
Some common trade names of PMMA
PMMA pricing pattern
12. PMMA trading pattern
How PMMA is used in building construction
• The unique properties of PMMA (optical clarity,
UV stability, resistance etc.) make it the ideal
material for construction applications such as
sound barriers, facades, aquaria and
greenhouses.
Is PMMA harmful?
• Our case series indicates that even small
volumes of PMMA used for cranioplasty may
cause severe side effects related to thermal
damage or to exposure of neural tissue to
methylacrylate monomer. Keywords: Chemical
neurotoxicity; Cranioplasty; Heat-induced nerve
damage; Polymethyl methacrylate.
