1 Polymers Chapter 8- Part 1 Manufacturing Processes, 1311 Dr Simin Nasseri Southern Polytechnic State University
Dec 14, 2015
1
PolymersChapter 8- Part 1
Manufacturing Processes, 1311
Dr Simin Nasseri
Southern Polytechnic State University
Manufacturing ProcessesProf Simin Nasseri
POLYMERS
Fundamentals of Polymer Technology Thermoplastic Polymers Thermosetting Polymers Elastomers Guide to the Processing of Polymers
Manufacturing ProcessesProf Simin Nasseri
Polymer
A compound consisting of long‑chain molecules, each molecule made up of repeating units connected together
There may be thousands, even millions of units in a single polymer molecule
The word polymer is derived from the Greek words poly, meaning many, and meros (reduced to mer), meaning part
Most polymers are based on carbon and are therefore considered organic chemicals
Manufacturing ProcessesProf Simin Nasseri
Natural polymers!
Natural Polymer: Silk fiber is produced by silk worms in a
cocoon, to protect the silkworm while it
metamorphoses in a moth.
The gooey liquid in okra, is a natural polymer used as a food thickener for thousands of years!
Manufacturing ProcessesProf Simin Nasseri
A tire is actually one giant network molecule, a molecule so big it takes two hands to pick it up!
A bowling ball contains only one molecule, too.
Polymer
Manufacturing ProcessesProf Simin Nasseri
Types of Polymers
Polymers can be separated into plastics and rubbers.
As engineering materials, it is appropriate to divide them into the following three categories:
1. Thermoplastic polymers
2. Thermosetting polymers
3. Elastomers
Plastics
Rubbers
Manufacturing ProcessesProf Simin Nasseri
Thermoplastic Polymers - Thermoplastics
Solid materials at room temperature but viscous liquids when heated to temperatures of only a few hundred degrees
About 70% of the tonnage of all synthetic polymers produced
This characteristic allows them to be easily and economically shaped into products
They can be subjected to heating and cooling cycles repeatedly without significant degradation
Symbolized by TP
Manufacturing ProcessesProf Simin Nasseri
Thermoplastic polymers
Milk bottleSoft drink bottles
Cafeteria trays
Manufacturing ProcessesProf Simin Nasseri
Thermosetting Polymers - Thermosets
Cannot tolerate repeated heating cycles as thermoplastics can
When initially heated, they soften and flow for molding
Elevated temperatures also produce a chemical reaction that hardens the material into an infusible solid
If reheated, thermosets degrade and char rather than soften
Symbolized by TS
Manufacturing ProcessesProf Simin Nasseri
Thermosetting Polymers
Plugs, Sockets and lamp holders
Manufacturing ProcessesProf Simin Nasseri
Elastomers (Rubbers)
Polymers that exhibit extreme elastic extensibility when subjected to relatively low mechanical stress
Although their properties are quite different from thermosets, they share a similar molecular structure that is different from the thermoplastics
Some elastomers can be stretched by a factor of 10 and yet completely recover
to their original shape!Wow !!
Manufacturing ProcessesProf Simin Nasseri
Elastomers
Rubbers, elasticsTire (Synthetic rubber)
Gloves (Natural rubber)
Manufacturing ProcessesProf Simin Nasseri
Examples of Polymers
Thermoplastics:
Polyethylene (PE), polyvinylchloride (PVC), polypropylene (PP), polystyrene, and nylon
Thermosets:
Phenolics, epoxies, and certain polyesters
Elastomers:
Natural rubber (vulcanized)
Synthetic rubbers, which exceed the tonnage of natural rubber
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Why are polymers important?
Manufacturing ProcessesProf Simin Nasseri
Reasons Why Polymers are Important:
Plastics can be molded into complex part shapes, usually with no further processing Very compatible with net shape
processing
On a volumetric basis, polymers: Are cost competitive with metals Generally require less energy to
produce than metals
Certain plastics are translucent and/or transparent, which makes them competitive with glass in some applications
Manufacturing ProcessesProf Simin Nasseri
General Properties of Polymers
Low density relative to metals and ceramics Good strength‑to‑weight ratios for certain (but
not all) polymers High corrosion resistance Low electrical and thermal conductivity
Manufacturing ProcessesProf Simin Nasseri
Limitations of Polymers
Low strength relative to metals and ceramics
Low modulus of elasticity (stiffness)
Service temperatures are limited to only a few hundred degrees
Viscoelastic properties, which can be a distinct limitation in load bearing applications
Some polymers degrade when subjected to sunlight and other forms of radiation
Manufacturing ProcessesProf Simin Nasseri
Polymer notes! (the first one was made in Australia)
Note Printing Australia (NPA), produced Australia's first polymer banknote in 1988, setting a new world standard in banknote technology.
The numerous benefits of polymer banknotes include improved security, durability, cost effectiveness, processibility and environmental responsibility.
Manufacturing ProcessesProf Simin Nasseri
Polymer notes!
By 1996, Australia had issued the world's first complete series of circulating polymer banknotes.
NPA has also produced polymer notes for Thailand, Papua New Guinea, Sri Lanka, Malaysia, Singapore, Brunei, Indonesia, Kuwait, Samoa, New Zealand, Romania, Bangladesh, Solomon Islands, Mexico, Nepal, Vietnam, and Chile.