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12 Cards in this Set
- Front
- Back
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Plastic |
An organic material that has the ability to flow into a desired shape when heat and pressure are applied and to retain the shape when they are withdrawn. |
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Plastic properties |
Flexible and stretchable Light weight Breakage resistance Barrier properties to oxygen, moisture & light Moulded into shapes Low temperature formability Strong heat sealability |
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Factors to consider in choice of plastic polymers |
No plastic provide absolutely gas & moisture barrier Mpt btn 650-2300°C Chemical resistance varies Additives in plastics can contaminate products |
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Classification of plastics |
Thermoplastic Thermosetting |
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Thermoplastic examples |
PE, Vinyl, PP, Nylon, PC |
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Thermosets examples |
Epoxy, Silicones, polyesters, polyamide |
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Plastics processes has 3 PHASES |
HEATING FORMING (SHAPING) COOLING |
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Differences |
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Thermoplastic |
Can be heated and reshaped without chemical change in their composition. |
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Plastics used |
PE (LDPE, HDPE, LLDPE) PP Polyamides (nylons) PVC Polystyrene Polyacrylonitrile (PAN) PC |
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Advantages of plastic |
Protection Beautiful shape and colours More comfort Cleaner world Longer life resources Flexible Not easily broken Low density and light weight Cheap |
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Disadvantages |
Not chemically inert Not impermeable Posses electro static charges that attracts particles |
