Plastics are synthetic or semi-synthetic organic solids that are moldable and consist of large chain-like molecules containing carbon. Plastics are less brittle than glass, corrosion resistant, light weight, and can be easily formed into complex shapes. Common plastics include thermoplastics, which can be remolded, and thermosetting plastics, which solidify permanently after heating. Plastics are manufactured through polymerization of monomers, compounding with additives, and molding techniques like injection molding, compression molding, and extrusion. Recent developments include bulletproof polymers, implantable medical polymers, and flexible plastic screens.

1. PLASTICS

2. DEFINITION AND CONCEPT
 A plastic material is any of a wide range
of synthetic or semi-synthetic organic solids that
are moldable
 Macro molecular
 Consists large chain like molecules containing
carbon

3. PROPERTIES OF PLASTICS
 Less brittle than glass ,hence can be made transparent and
smooth.
 Corrosion resistance
 Low electrical and thermal conductivity, insulator
 Easily formed into complex shapes, can be formed, casted
and joined.
 Wide choice of appearance, colors and transparencies
 Light weight but posses good strength and rigidity.
 Low moisture absorbtion.
 Heat resistance.

4. TYPES OF PLASTICS
 THERMOPLASTICS
 Thermoplastics are the plastics that do not undergo
chemical change in their composition when heated
and can be molded again and again
 THERMOSETTING PLASTICS
 Thermosets can melt and take shape once; after they
have solidified, they stay solid. In the thermosetting
process, a chemical reaction occurs that is
irreversible

5. MANUFACTURE OF PLASTICS
 The production of plastics can be roughly divided
into four categories:
1. Acquiring the raw material or monomer.
2. Synthesizing the basic polymer.
3. Compounding the polymer into a material that can
be used for fabrication.
4. Molding or shaping the plastic into its final form.

6. 1.Raw Materials
 Historically, resins derived from vegetable matter
were used to produce most plastics.
 This included such materials as cellulose (from
cotton), furfural (from oat hulls), oils (from seeds)
and various starch derivatives.
 Today, most plastics are produced from
petrochemicals which are widely available and tend
to be cheaper than other raw materials.

7. 2. Synthesis of the Polymer
 The first step in plastic manufacturing is
polymerization.
 The two basic methods by which polymerization can
occur are addition and condensation reactions.
 This is achieved by adding reinforcements such as
glass or carbon fibers to the plastics, increasing their
strength and stability.

8. Additives
 Chemical additives can be used in the production of
plastics to achieve certain characteristics. These
additives include:
1. antioxidants to protect the polymer from
degradation by ozone or oxygen
2. ultraviolet stabilizers to protect against weathering
3. plasticizers to increase the polymer’s flexibility
4. lubricants to reduce friction problems
5. pigments to give the plastic colour

9. 3.Shaping and Finishing
1.COMPRESSION MOLDING
Pre-measured amount of polymer introduced into
the heated mold then the top half comes down and
applies pressure. Usually uses thermosetting
plastics and produces products like dishes,
container caps, etc.

11.  EXTRUSION
 A device, called an extruder, forces softened plastic
through a shaped die from which it may emerge in
almost any form, including a circular rod or tube,
and a wide, flat sheet.
The driving force is supplied by a screw which
provides constant pressure.

12.  INJECTION MOLDING
 Involves one or more extruders which force melted
plastic into a cold mold where it is allowed to set to
the required shape.
 An adaptation of this method is injection blow
molding which is used to make plastic pop bottles.
 A thick-walled plastic tube is initially injection-molded
around a blowing stick and is then
transferred to a blowing mold.
The tube is reheated and expanded to the shape of
the mold by passing air down the blowing stick.

13. THERMOSETTING RESINS
 Once hardened and set, they do not soften with
application of heat.
 Reason: consist of linear, relatively low molecular wt
thermoplastic polymer chains with crosslinks which
bond the chains together. when heated the entire
structure becomes a single molecule.
 Objects made of this can be used at higher
temperatures without damage.
 More stronger and harder than thermoplastic resins.

14. APPLICATIONS
 Telephonic receivers, electric plugs, radio and TV
cabinets, camera bodies, automotive parts, electric
baker, switch panels.
 EXAMPLES
 Phenol formaldehyde resins
 Urea formaldehyde resins
 Melanine formaldehyde resins
 Polyester resins.
 Epoxy resins
 Silicone resins

16. THERMOPLASTICS
 Can be repeatedly softened by heat and hardened by
cooling.
 Reason: they are composed of linear and long chain
molecules. application of heat weakens the
intermolecular bonds by increasing thermal agitation
of the molecules and hence the material softens.
 Cannot use at high temperatures as they will soften
under heat.
 Usually supplied as granular materials.
 Comparatively software and less strong.

17. APPLICATIONS
 Toys, combs, toilet goods, photographic films,
insulating tapes, hoses, electric insulation
 EXAMPLES
 Polystyrene
 Abs
 Methacrylate
 PVC
 Polycarbonate
 Polychoroacetal

19. DISADVANTAGES OF USING PLASTICS
 Low strength
 Low useful temperature range (up to 600 oF)
 Less dimensional stability over period of time (creep effect)
 Aging effect, hardens and become brittle over time
 Sensitive to environment, moisture and chemicals
 Poor machinability

20. LATEST DEVELOPMENTS
 Bullet Proof Polymer - Scientists at Rice
University, Texas have created a new super
polymer material that can stop a 9mm bullet and
seal the hole behind it.
 The material is a complex multiblock copolymer
polyurethanem, which is a synthetic compound build in the
lab.

21.  Plastics Blood - Developed by the University of
Sheffield to mimic haemoglobin, for use in trauma
situations
where blood is needed quickly
 The "plastic" blood consists of an iron-containing
porphyrin which is permanently bonded
to a hyperbranched polymer (HBP or dendrimer)
"shell"

22.  Plastic Solar Cells - A polymer solar cell that can
produce electricity from sunlight by the photovoltaic
effect provides a lightweight, disposable and
inexpensive alternative to traditional solar panels
 PET –polyethylene terephthalate
 ITO – indium tin oxide

23.  Implantable Polymers - Medical grade and
implantable biomaterials such as PEEK will be used
in neurological applications to help control epilepsy,
Parkinson’s d.
 Commercial - Space Flights Lightweight carbon
composite materials will be crucial in the realisation
of sub-orbital tourist spaceflightsisease and brain
trauma

24.  3D Printed - Body Parts Using plastic materials
such as PMMA car parts can be printed at home and
doctors can produce replica livers or kidneys for
transplant patients.

25.  Flexible Plastic Screens - Organic light-emitting
diodes are placed on plastic foil to create electronic
devices with flexible displays.

26. THE FUTURE
 The future (2022) - The 2022 FIFA World Cup
Qatar Showcase Stadium has been designed to use
super reflective, triangulated PVC fabric to create a
zero carbon, sustainable stadium providing
comfortable playing conditions