Polymers Flashcards
(47 cards)
What is a thermoplastic ?
A material that can be repeatedly reheated and reshaped.
Describe the structure of thermoplastics ?
Long linear chain molecules held by forces
What is a thermosetting polymer ?
A material which when heated undergoes a chemical change - cannot be reheated and reshaped even at high temperatures
Describe the structure of thermosetting plastics ?
the molecules form rigid cross links
What is an elastomer ?
A material which at room temperature can be deformed under pressure and then upon release of pressure , return to the original shape
Describe the structure of elastomers ?
Have weak bonds which allows them to stretch easily
What are the stock forms that polymers are available in ?
- granules
- sheet
- rods / other extruded forms such as tubes
- foam
- powder
- film
Why do polymers not require additional finishing processes ?
- polymers are already self finishing
- can have pigments added to the manufacturing process therefore required no additional secondary finishing processes
What are synthetic polymers made from ?
Crude oil
How long does it take for synthetic plastics to degrade ?
- 100 years
What are properties of low density polyethylene?
- very tough
- good chemical resistance
- weather proof
- low level of rigidity
Common uses of LDPE ( low density polyethylene ) :
- squeeze detergent bottles
- toys
- carrier bags
- bin liners
- food trays
What is the safe working temperature of thermoplastics ?
- 65 to 95
- nylon has a safe working temperature of 150 degrees
What are properties of high density polyethylene ?
- weatherproof
- tough
- good chemical resistance
What are the uses of HDPE ?
- chemical drums
- toys
- long life carrier bags
- buckets
- bowls
What are properties of polypropylene ?
- good chemical resistance
- tough
- good fatigue resistance
Uses of polypropylene ?
- rope
- folders
- folio cases
- food containers
What are properties of high impact polystyrene ?
- hard
- rigid
- available in translucent
- tough
Uses of HIPs ?
- yoghurt pots
- bin linings
- single use drink cups
- toilet seats
What are the uses of ABS ?
- telephone handsets
- rigid luggage
- domestic appliances
- handles
- computer housing
- calculator casings
What are properties of Abs ?
- Tough
- hard
- available opaque
What are the properties of pmma ?
- tough
- hard
- good chemical resistance
- available translucent
Uses of pmma ?
- car light casings
- lighting units
- lighting covers
- baths
What are the properties of nylon ?
- tough
- corrosion resistant
- good temperature resistance
- low coefficient of friction
