Polymers Flashcards
what are thermoplastics and what properties do they have?
- most commonly used plastic
- long chain molecules with no fixed structure or pattern
- soft
- flexible
- some shape memory
what is the thermoplastic cycle? [4]
heated
softened and moulded
cools
hardens
what is LDPE and its triangle number?
Low density polyethylene [4]
what are LDPE properties and uses?
- flexible
- tough
- translucent or opaque
- chemical resistant
- carrier bags, squeezy bottles, toys
what is HDPE and its triangle number?
High density Polyethylene [2]
what are HDPE properties and uses?
- tough
- high strength to weight ratio
- chemical resistant
- bleach bottles, buckets, bins
what is PP and its triangle symbol?
Polypropylene [5]
what are PP properties and uses?
- tough
- flexible
- fatigue resistant
- chemical and solvent resistant
- clear or transparent
- boat rope, Tupperware, medical equipment
what is plastic fatigue resistance?
resistance to deformation after dynamic stress
-stops cracks appearing after constant use
what is HIPS and its triangle symbol?
High impact polystyrene [6-PS]
what are HIPS properties and uses?
- rigid
- lightweight
- high impact strength
- retains heat without deforming
- glossy
- food safe
- plastic cutlery, yoghurt pots salad bowls
what is ABS and its triangle number?
Acrylonitrile Butadiene styrene [7-other]
what are ABS properties and uses?
- hard and tough
- good impact strength
- resistant to oils, acids, alkalis and grease
- easily moulded
- high quality surface finish
- used for appliance casings, safety helmets and car bumpers
what is PMMA and its triangle number?
Polymethyl methacrylate or Acrylic [7]
what are PMMA properties and uses?
- tough
- lightweight
- shatter resistant
- clear or opaque
- poor chemical resistance
- baths, glasses, shower trays
what is nylon and its triangle number?
thermoplastic polymer [7]
what are Nylons properties and uses?
- abrasion resistant
- heat resistant
- durable
- low coefficient of friction
- used for seat belts, rope, parachutes, carpets
how is PVC made to be flexible?
plasticisers are added to decrease its viscosity
what are flexible PVC properties and uses?
- water resistant
- chemical resistant
- hose pipes, electrical insulation, clothing
what is rigid PVC and its triangle number?
polyvinyl chloride [3-v or 3- pvc]
what are rigid PVC properties and uses?
- tough
- hard
- fire retardant
- good chemical and weather resistant
- gutters, pipes, window frames
what is PET and its triangle number?
Polyethylene terephthalate [1]
what are PET properties and uses?
- strong
- rigid
- chemical resistant
- water resistant
- drink packaging [juice and water]
How do thermosets differ to thermoplastics?
more brittle and suited for stiffer mouldings
how do you thermoset plastics?
- condensation polymerisation [1 water molecule produced]
what is the structure of thermosets?
- long chain molecules
- rigid molecular structure when cured
- endothermic reaction
what is the thermoset cycle? [5]
heated softened + moulded baked hardens [burns if heated]
what are the properties of thermosets?
- hard
- waterproof when solid
- difficult to mould
- can’t be reheated or reshaped
- retain shape well at high temperatures
- used as adhesives
what is UF and its properties?
Urea Formaldehyde
- hard
- opaque
- organic compound
- good resistance to deformation by heat
- high tensile strength
UF uses?
- adhesives
- electrical casings
- sockets and switches
what is MF and its properties?
Melamine Formaldehyde
- hard
- scratch resistant
- opaque
- heat and chemical resistant
Melamine Formaldehyde uses?
- surface coatings
- decorative laminates
- toilet seats
- kitchen utensils
what is Polyester resin and its properties?
- most common resin in marine industry
- water resistant
- heat resistant
- chemical resistant
- needs to be mixed with catalyst to cure
Polyester resin uses?
- used in glass reinforced plastic
- boat hulls
- bath tubs
- chair seats
what is epoxy resin and its properties?
- clear resin that needs to be mixed with a catalyst to cure
- hard
- tough
- maintains structure at high temperatures
- good chemical resistance
Epoxy resin uses?
- adhesive for disimilar materials
- surface coatings
- encapsulating electrical components [LEDs]
