B. Polymers Flashcards
What is the difference between thermoforming and thermosetting polymers?
Thermosetting plastics undergo a chemical change and once formed, cannot be reformed. Thermoforming plastics can be reshaped multiple times
Why are thermoforming plastics able to be reshaped?
TF plastics are loosely entangled with very few cross links, allowing the chains to slide past each other when heated.
Why can’t thermosetting plastics be reshaped?
TS plastics have rigid cross-linked polymer chains that set when heated and cannot be reformed.
Which polymers are thermoforming?
Polypropylene (PP)
High density polyethylene (HDPE)
High impact polystyrene (HIPS)
Polyethylene terephthalate (PET)
Acrylic (PMMA)
Polyvinyl chloride (PVC)
Which polymers are thermosetting?
Polyester resin (PR)
Urea formaldehyde (UF)
Epoxy Resin (ER)
Phenol formaldehyde (PF)
Melamine formaldehyde (MF)
What are the uses of Polypropylene (PP)?
Uses: Kitchen, medical properties, rope
What are the properties of Polypropylene (PP)?
Thermoforming
Properties: Flexible, tough, lightweight, food safe
What are the properties of Acrylic (PMMA)?
Thermoforming
Properties: Tough but brittle when thin. Easily scratched, formed and bonded
What are the uses of Acrylic (PMMA)?
Uses: Car lights, alternative to glass, modern baths, clothing
What are the properties of High density polyethylene (HDPE)?
Thermoforming
Properties: Lightweight, rip and chemical resistant
What are the uses of High density polyethylene (HDPE)?
Uses: Milk bottles, pipes, crates, wheelie bins
What are the properties of High impact polystyrene (HIPS)?
Thermoforming
Properties: Flexible, impact resistant, lightweight, (can be) food safe
What are the uses of High impact polystyrene (HIPS)?
Uses: Yoghurt pots, vacuum forming
What are the uses of polyethylene terephthalate (PET)?
Thermoforming
Properties: Blow moulded, chemically resistant, fully recyclable
What are the uses of polyethylene terephthalate (PET)?
Uses: Drinks bottles, food containers, yarn
What are the properties of Polyvinyl chloride (PVC)?
Thermoforming
Properties: Flexible, easily extruded, tough and resistant to chemicals
What are the uses of Polyvinyl chloride (PVC)?
Uses: Raincoats, pipes, electrical tape
What are the properties of Polyester resin (PR)?
Thermosetting
Properties: Good electrical insulator, hard
What happens when glass is added to Polyester resin (PR)?
PR becomes tough when mixed with glass strands to form Glass reinforced plastic (GRP)
What are the uses of Polyester resin (PR)?
Encapsulation (think microfibre), boat halls (as GRP)
What are the properties of Urea formaldehyde (UF)?
Thermosetting
Uses: High tensile strength, heat resistant, electrical insulator, hard, brittle, easily injection moulded