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Polymer (Thermoplastic Polymers (solid material at room temperature but…
Polymer
Nature of Polymers
Polymer
a compound consisting of long-chain molecules, each molecule made up of repeating units connected together
they 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
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Natural Polymers
The gooey liquid in okra , is a natural polymer used as a food thickener for thousand of years
Silk fiber is produced by silk worms in a cocoon to protect the silkworm while it metamorphoses in a moth
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Thermoplastic Polymers
solid material at room temperature but viscous liquids when heated to temperature of only a few hundred degrees
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(e.g products: Milk bottle, soft drink bottles, Cafeteria trays)
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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 a 10 and yet completely recover to their original shape
(e.g products: Tire(Synthetic rubber), glove(natural rubbers) ,rubbers,elastics)
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
Important of Polymers
Plastics can be molded into complex part shapes, usually with no further processing
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on a volumetric basis, polymers
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certain plastics are translucent and/or transparent , which makes them competitive with glass in some applications
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Limitations of Polymers
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Viscoelastic properties, which can be a distinct limitation in load bearing applications
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