1. Polyolefins are polymers produced from olefin or alkene monomers, with ethylene being the simplest and most common monomer. They are produced via polymerization of ethylene extracted from petroleum through cracking of longer hydrocarbon chains. 2. Low-density polyethylene (LDPE) is produced via free radical polymerization of ethylene under high pressures of 1000-3000 atm and temperatures of 200-275°C. It is used for products like bottles and tubing due to its low cost, chemical resistance, and flexibility. 3. High-density polyethylene (HDPE) is produced using Ziegler-Natta catalysts under lower pressures than LDPE. It is stronger

1. Polyolefin
DEPARTMENT OF DYESTUFF TECHNOLOGY

2. What are polyolefins :
A polyolefin is a polymer produced from an olefin or alkene as a monomer.
In organic chemistry, an alkene, olefin or olefine is unsaturated chemical
compound containing at least one carbon to carbon double bond.
The simplest alkene is ethylene
Olefins source :
The most common industrial synthesis path for alkenes is cracking of
petroleum.
Cracking is the process whereby complex organic molecules are broken down
into
simpler molecules (e.g. light hydrocarbons) by the breaking of carbon-carbon
bonds in
the precursors.
Ethylene is produced by cracking higher hydrocarbons of natural gas or
petroleum
DEPARTMENT OF DYESTUFF TECHNOLOGY

3. LOW-DENSITY POLYETHYLENE (LDPE)
Polyethylene was first formed in an experiment in 1933 at the laboratories of ICI .
The experiment was to react ethylene with benzaldehyde at 170 C and 2000 atm.
The reaction formed a waxy solid which appeared, however, to be a high polymer
of ethylene rather than a reaction product of ethylene and benzaldehyde.
Repetition of the experiment resulted in decomposition of the ethylene to carbon
black and hydrogen.
HISTORY :

4. PROCESS : LDPE is manufactured by polymerization in reactors
TEMP : 200 to 275C
PRESSURE : 1000 to 3000 atm
Ethylene is a supercritical fluid having a density of 0.4 to 0.5 g/ml
The polymer remains dissolved in the
ethylene phase.
The polymerization is a free radical
reaction. Initiation can be by either oxygen
or peroxides.
LOW-DENSITY POLYETHYLENE (LDPE)

5. I N I T I A T I O N : Initiation can be by either oxygen or peroxides
The termination and branching reactions are not the only ones taking place, but they
are among the quite important ones
The greater the amount of branching, the lower the density.
As the pressure increases, the rates of the propagation steps increase faster than the
rates for the termination and branching steps. High pressure thus favors higher
densities and less branching (and higher molecular weights).
LOW-DENSITY POLYETHYLENE (LDPE)

6. If peroxides are used to initiate the
reaction,
they are added to this high-pressure
stream, and the mixture is fed to the
reactor.
Low molecular weight waxes are
separated and the ethylene is
recycled.
Separating the ethylene into a low-
pressure recycle stream and molten
polyethylene,
which is then fed to an extruder,
pelletized, and stored.
INDUSTRIAL PROCESS :
Ethylene, together with a moderator, or
telogen, for molecular weight control.
LOW-DENSITY POLYETHYLENE (LDPE)

7. The largest producer/licensors
Union Carbide, Dow, Du Pont,
and U.S. Industrial Chemicals
in the United States, and ICI
and BASF outside the United
States.
Uses & Applications
• Dispensing bottles, wash bottles,
tubing, and laboratory equipment.
 Semi-rigid
Good chemical resistance
 Translucent
Low water absorption
 Low cost
Properties
LOW-DENSITY POLYETHYLENE (LDPE)

8. HIGH- DENSITY POLYETHYLENE (HDPE)
The principal catalyst systems used to produce
high-density polyethylene were all discovered in
the early 1950s.
The first was the use of a supported, reduced
molybdenum oxide. This catalyst was discovered
by research workers at Standard of Indiana.
It was also during 1953 that Ziegler and his co-
workers discovered the reduced titanium
chloride, aluminum alkyl catalysts for the
polymerization of ethylene
HISTORY :

9. HIGH- DENSITY POLYETHYLENE (HDPE)

10. The process uses a Ziegler catalyst, and the
product is formed as a slurry in a hydrocarbon
diluent.
Ethylene is pumped into the reactor and
reacted at about 60 psig pressure.
The heat of polymerization is very large ,
and in this particular configuration it is
removed by continuously taking a
slipstream from the bottom of the reactor
and flashing it down to about 3 psig.
A slipstream of this bottom
stream is taken off through a
centrifuge to concentrate and
remove the product.
The final product is a
polyethylene fluff which is
pelleted
HIGH- DENSITY POLYETHYLENE (HDPE)

11. H IGH-DENSITY POLYETHYLENE
Union Carbide has developed supported chromium oxide catalysts suitable for operation in
the gas phase.
The reactor operates as a fluidized bed of
polyethylene particles.
The ethylene is recirculated by blowing
through air coolers where the heat is removed.
The polyethylene exits as a dense mixture of
polyethylene in unreacted ethylene to a
disengaging space where the ethylene is freed.
The powdered polyethylene passes out to the
finishing section.
HIGH- DENSITY POLYETHYLENE (HDPE)

12. : Relatively opaque form of polyethylene having a
dense structure with few side branches off the
main carbon backbone.
Properties
 Hard and opaque plastic ( crystalline structure)
 Higher thermal stability than that of LDPE
Stronger mechanical properties
(Higher Intermolecular forces than that of LDPE)
Cr/SiO2 catalysts
Ziegler-Natta
metallocene
HIGH- DENSITY POLYETHYLENE (HDPE)

13. Uses & Applications
• Pipe, toys, bowls, buckets, milk bottles, crates,
tanks, and containers.
HIGH- DENSITY POLYETHYLENE (HDPE)

14. Polypropylene History
Prior to 1954 most attempts to produce
plastics from polyolefins had little commercial
success
PP invented in 1955 by Italian Scientist F.J.
Natta by addition reaction of propylene gas
with a sterospecific catalyst titanium
trichloride.
Isotactic polypropylene was sterospecific
(molecules are arranged in a definite order in
space)
Polypropylene is similar in manufacturing
method and in properties to PE
POLYPROPYLENE

15. : A thermoplastic polymer, used in a wide variety of applications
Food packaging, ropes, textiles
Thermal pants and shirts made for the military
Laboratory equipment, automotive components
including
POLYPROPYLENE

16. POLYPROPYLENE
 Crystallinity and Young’s modulus
: Intermediate level of
LDPE and HDPE
 Color : translucent, opaque
 Melting point : 160 deg. C
Characteristics
POLYPROPYLENE

17. Crystallographic properties:
Isotactic polypropylene
atactic polypropylene
Ziegler-Natta polymerization
(titanium chloride catalyst)
Radical polymerization
(i.e., initiator : AIBN)
Metallocene catalyst
Structure Synthesis method Properties
Hard crumps
of
crystalline polymer
Soft rubber
Thermoplastic
elastomer
Poly-1-butene Poly(4-methyl-1-pentene)
Other isotactic polymer
POLYPROPYLENE

18. Physical Properties of Polypropylene
Polypropylene LDPE HDPE
Optical Transparent to
opaque
Transparent to
opaque
Transparent to opaque
Tmelt 175 C 98 – 115 C 130 –137 C
Tg -20 C -100 C -100 C
H20
Absorption
0.01 – 0.03 Low < 0.01 Low < 0.01
Oxidation
Resistance
Low, oxides
readily
Low, oxides
readily
Low, oxides readily
UV Resistance Low, Crazes
readily
Low, Crazes
readily
Low, Crazes readily
Solvent
Resistance
Resistant
below 80C
Resistant below
60C
Resistant below 60C
Alkaline
Resistance
Resistant Resistant Resistant
Acid
Resistance
Oxidizing
Acids
Oxidizing Acids Oxidizing Acids
POLYPROPYLENE

19.  Synthetic rubber
 Thermoplastic elastomer
Synthesis
 Color : light yellow elastic semi-solid
 Gas impermeable polymer
Characteristics
- Enable gas storage
Radical polymerization
Cationic addition pmz
Anionic addition pmz
: PIB, used in many applications requiring an airtight rubber
including
· Liners for tubeless tyres
· Inner tubes
· Inner tubes for footballs, basketballs etc
· Stoppers for medicine bottles
· In sealants and adhesives
· O-rings
· Joint replacements (biomedical)
· Chewing gum
Gas mask Rubber grove
POLY ISOBUTYLENE

20. Synthesis
Natural polymer, havested in hevea tree
Applications
Copolymerization with polyisobutylene
Poly (isobutylene-co-isoprene)
Vulcanization
Cross linked
Diene Elastomers

21. Diene elastomers Neoprene
 Polychloropene (CR), NeopreneTM (Dupont)
 Good mechanical strength
 High ozone and weather resistance
 Good aging resistance  Low flammability
 Good resistance toward chemicals
 Moderate oil and fuel resistance
 First synthetic elastomer to be a hit commercially
Polar unit
But….. Expensive ..

22. Vinyl Halide polymers PVC
Of all the synthetic thermoplastics used today, polyvinyl chloride (PVC) is probably the
one with the oldest pedigree. Vinyl chloride monomer (VCM) was first produced by
Regnault in France in 1835 and its polymerization was recorded in 1872 by Baumann,
who exposed sealed tubes containing vinyl chloride to sunlight. The earliest patents for
PVC production were taken out in the USA in 1912 and pilot plant production of PVC
began in Germany and the USA in the early 1930's.
The industrial production of PVC using emulsion and suspension techniques was taking
place in Britain, Germany and the USA by 1939. Total production reached 50,000 tons
by 1945, and in the course of the following years, increased rapidly.
PVC is now the second most used plastic in the world.
About PVC

23. ► Properties
•The chlorine atom on every second carbon in the main-
chain of polyvinyl chloride produces polarity.
•The large negative chlorine atoms also cause some steric
hindrance and electrostatic repulsion, which reduce the
flexibility of the polymer chain.
•So PVC have high rigidity and strength coupled with
brittleness, fair heat deflection temperature, good
electrical resistance, and high solvent resistance.
Vinyl Halide polymers PVC

24. • Building panels, siding, windows, rainwater gutter and downspouts.
• Pipe, fittings, and conduit, particularly for water and for chemical processing.
• Blow-molded bottle.
• Thermoformed sheet for packaging.
• In Europe for magnetic tape.
► Application
PVCVinyl Halide polymers

25. Polytetrafluoroethylene
Polytetrafluoroethylene is better known by the trade name Teflon®. It's used to make non-
stick cooking pans, and anything else that needs to be slippery or non-stick. PTFE is also
used to treat carpets and fabrics to make them stain resistant. What's more, it's also very
useful in medical applications. Because human bodies rarely reject it, it can be used for
making artificial body parts.
Polytetrafluoroethylene, or PTFE, is made of a carbon backbone chain, and each carbon
has two fluorine atoms attached to it. It's usually drawn like the picture at the top of the
page, but it may be easier to think of it as it's drawn in the picture below, with the chain of
carbon atoms being thousands of atoms long.
About Polytetrafluoroethylene
Vinyl Halide polymers

26. Polytetrafluoroethylene
•Insulating electrical wiring in high-temperature environments; motors,
locomotives, aircraft engines, missiles, and spacecraft.
•Lighting fixtures, stoves, and oven.
•Switches, controls, and computers.
•Heating cable for pipe tracing in chemical plants and refineries.
•Gasket, seals, packing, bearings, and cooking utensils
•Electrical insulators for radar and television.
•Lining pipe, fittings, valves, and pump in industrial plant and hydraulic and
fuel hose in aircraft, truck, buses, and trains.
► Application
Vinyl Halide polymers