This document provides information about polypropylene, including: - Its discovery in 1951 by Phillips Petroleum chemists who first polymerized propylene, and its commercial production starting in 1957. - Its structure as an addition polymer made from the monomer propylene, with methyl groups attached to every other carbon in the backbone chain. - Its properties including chemical resistance to many solvents, bases and acids, and its mechanical properties of being tough and flexible. - Its uses in products like food containers, medical devices, ropes, piping systems and more due to its resistance to corrosion and chemicals. - How isotactic and syndiotactic polypropylene structures are controlled

1. By
Engineer Nathan.J.Chifamba
B-tech Hons Chemical and Process Systems Engineering (Harare Institute of Technology ,Zimbabwe)
M-Tech Polymer Science and Technology
(Amity University Gurgaon India)
Polymer Synthesis Presentation
(Dr Nidhi Goel lecturer)
22/12/2016

2. Polypropylene

3. Brief History
• Phillips Petroleum chemists J. Paul Hogan and Robert L. Banks first
polymerized propylene in 1951. Propylene was first polymerized to a
crystalline isotactic polymer by Giulio Natta as well as by the German
chemist Karl Rehn in March 1954.This pioneering discovery led to
large-scale commercial production of isotactic polypropylene by the
Italian firm Montecatini from 1957 onwards.Syndiotactic
polypropylene was also first synthesized by Natta and his coworkers

4. INTRODUCTION
• An addition polymer made from the monomer propylene, it is rugged
and unusually resistant to many chemical solvents, bases and acids.
• Structurally, it's a vinyl polymer, and is similar to polyethylene, only
that on every other carbon atom in the backbone chain has a methyl
group attached to it. Polypropylene can be made from the monomer
propylene by Ziegler-Natta polymerization and by metallocene
catalysis polymerization.
• Polypropylene is the world's second-most widely produced synthetic
plastic, after polyethylene.
• Polypropylene is in many aspects similar to polyethylene, especially in
solution behaviour and electrical properties. The additionally present
methyl group improves mechanical properties and thermal resistance,
while the chemical resistance decreases.

5. PROPERTIES
Chemical :The properties of polypropylene depend on the molecular weight and molecular weight
distribution and crystallinity.Isotactic polypropylene has a greater degree of crystallinity and results in a
stiffer material that is more resistant to creep than both atactic polypropylene and polyethylene.
Mechanical :Polypropylene is normally tough and flexible, especially when copolymerized with ethylene.
Polypropylene is reasonably economical and has good resistance to fatigue.
Polypropylene is at room temperature resistant to fats and almost all organic solvents, apart from strong
oxidants. Non-oxidizing acids and bases can be stored in containers made of PP. At elevated temperature,
PP can be dissolved in non-polarity solvents such as xylene, tetralin and decalin. Due to the tertiary carbon
atom PP is chemically less resistant than PE
Degradation:Polypropylene is liable to chain degradation from exposure to heat and UV radiation such as
that present in sunlight. Oxidation usually occurs at the tertiary carbon atom present in every repeat unit. A
free radical is formed here, and then reacts further with oxygen. In external applications, it shows up as a
network of fine cracks and crazes that become deeper and more severe with time of exposure hence UV-
absorbing additives must be used. The polymer can also be oxidized at high temperatures, a common
problem during molding operations. Anti-oxidants are normally added to prevent polymer degradation.
Microbial communities isolated from soil samples mixed with starch have been shown to be capable of
degrading polypropylene.Polypropylene has been reported to degrade while in human body as implantable
mesh devices
PP can be made translucent when uncolored but is not as readily made transparent as polystyrene, acrylic,
or certain other plastics. It is often opaque or colored using pigments

6. Uses
• Used to make lids of flip top bottles(high fatigue resistance)
• Used as a dielectric in low loss capacitors ((~2–20 µm)
• piping systems(resistance to corrosion and chemical leaching,
• Medical or laboratory use can be made from polypropylene because it can
withstand the heat in an autoclave.
• For consumer-grade kettles,food containers made from it will not melt in
the dishwasher
• Plastic chairs
• as insulation for electrical cables for in low-ventilation environments
• roofing membranes as the waterproofing top layer
• Production of stationery folders, packaging, and storage boxes
• PP Fibres as concrete additives to increase strength and reduce cracking
and spalling.ropes

7. 7
Ziegler-Natta Catalysts (Coordination)
• The more regular arrangement of Z substituents makes isotactic and
syndiotactic polymers pack together better, making the polymer stronger and
more rigid.
• Chains of atactic polymer tend to pack less closely together, resulting in a
lower melting point and a softer polymer.
• Radical polymerizations often afford atactic polymers.
• Reaction conditions can greatly affect the stereochemistry of the polymer
formed.
• The use of Ziegler-Natta catalysts permits easy control of polymer
stereochemistry, with the formation of isotactic, syndiotactic, or atactic
polymers dependent on the catalyst used.
• Most Ziegler-Natta catalysts consist of an organoaluminum compounds such
as (CH3CH2)2AlCl or TiCl4.

8. Isotactic Polypropylene Mechanism
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9. Syndiotactic Mechanism
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10. Any Questions!!!!