polymers

=polymers (solid plastics)=

Properties Advantages; Light weight (low specific gravity (SG)), good thermal and electrical resistance, good surface finish (from dyes), available in many colours Disadvantages; Low strength compared to metals, not suitable for high temperatures, dimensionally unstable = = =Common Thermosoftening Plastics (Thermo Plastics)=

Can be reworked by reheating
Examples Polyethylene (polythene) - examples, plastic bags and sheeting, bottles, pipes Properties - Transparent, nontoxic, good chemical resistance SG (specific gravity) = 0.96 media type="custom" key="10255939"

Polyamides (nylon) - examples; clothing, rope, gears Properties - Translucent, Strong, good electrical insulator, good abrasion resistance SG = 1.06 - 1.19 media type="custom" key="10255991"

Polymethyl meyhacrylate (acrylic, Perspex) - examples; windows, roofing, light fixtures Properties - Transparent and translucent, tough, machines well, moulds well SG = 1.15 - 1.18 media type="custom" key="10256121"

=Common Thermosetting Plastics=

Cannot be reworked
Polystyrene – examples; insulation in refrigerators and buildings, packaging, wall and ceiling tiles Properties – Transparent and opaque, moulds well, good insulator, absorbs impact SG = 1.05 - 1.15 media type="custom" key="10256261"

Melamine formaldehyde - examples; light fittings, dinnerware Properties - Tough and scratch resistant, chemically inert SG = 1.76 - 1.98 media type="custom" key="10256311"

Silicones - examples; silicone resins, silicone greases, silicone rubber (not to be confused with the element silicon which is one of the elements within silicones) Properties - high stability, water repellent SG = 2.0 media type="custom" key="10256363"

=Elastomers= An elastomer can be stretched repeatedly to at least twice its length and when released returns to its original length Example rubber media type="custom" key="10256523"

How much do you remember? Complete the following quiz =quiz - polymers= (click on the link)

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=ceramics=