Polymers Flashcards
Stock forms
Granules - a small particle of plastic
Sheet - large flat sections of polymer in varying thicknesses
Film - very thin sheet polymer
Rods and other extruded forms - can be designed to a specific form e.g. Curtain rail. But they have the same cross section along their length
Bar - a solid form square or round
Tube - hollow in cross-section, square, rectangular or round
Foam - solid form made by including air or other gases e.g. Styrofoam
Powder - very fine granules
General characteristics
Majority made via fractional distillation of crude oil
Synthetic polymers - made from crude oil and take 100’s of years to degrade
Self finishing - require no additional finishing processes as they can be pigmented
Thermoplastic
A material that can be reheated and reshaped repeatedly, allowing it to be recycled after its initial use
Thermoset polymer
A material that ,when heated, undergoes a chemical change whereby the molecules form rigid cross-links. They can’t be reheated and reshaped, even at very high temperatures
Elastomer
A material that, at room temperature, can be deformed under pressure and then, upon release of the pressure, will return to its original shape
Low density Polyethylene (LDPE)
Tough Good chemical resistance Weather proof Available in translucent Low level of rigidity Safe working temperature 65 degrees C
Uses:
Squeeze detergent bottles Toys Carrier bags Bin liners General packaging Food wrap Food trays
High Density polyethylene
Tough
Weather proof
Good chemical resistance
Safe working temperature 65 degrees
Uses:
Chemical drums Jerry cans Toys Kitchenware Long life carrier bags Buckets Bowls
Polypropylene (PP)
Available in translucent Good chemical resistance Tough Good fatigue resistance Safe working temperature 180 degrees C
Uses:
Rope Folders Folio cases Food containers Medical equipment
High impact polystyrene (HIPS)
Hard Rigid Available in translucent Tough Safe working temperature 70 degrees
Uses:
Yoghurt pots Refrigerator linings Single use drink cups Toilet seats Instrument control knobs
Acrylonitrile butadiene styrene (ABS)
Tough
Hard
Available in opaque
Safe working temperature 80 degrees C
Uses:
Telephone handsets Rigid luggage Domestic appliances e.g. Food mixers Handles Computer housings Remote control casings Calculator casings
Polymethylmethacrylate (PMMA)
Tough Hard Good chemical resistance Available in translucent Safe working temperature 95 degrees C
Uses:
Car light casings CNC laser cut items Lighting units Lighting covers Baths
Nylon
Tough Corrosion resistant Good temperature resistance Low coefficient of friction Safe working temperature 150 degrees Thermoplastic
Uses:
Bearings Gears Curtain rails Textiles Cable ties
Rigid polyvinyl chloride (uPVC)
Rigid Opaque Tough Hard Good weathering resistance Good chemical resistance Safe working temperature 95 degrees C
Uses:
Window frames External doors Guttering and downpipes Water service pipes Bank cards
Flexible polyvinyl chloride (PVC)
Available of translucent Tough Flexible Good weathering resistance Good chemical resistance Safe working temperature 95 degrees C
Uses:
Hose pipes Cable insulation Medical grade tubing Inflatable products Imitation leather
Urea formaldehyde
Hard Heat resistant Thermoset Good electrical insulator Brittle Safe working temperature 80 degrees C
Uses:
Electrical fittings
Adhesives
Melamine formaldehyde
Hard Opaque Tough Heat resistant Food safe Chemical resistant Safe working temperature 130 degrees
Uses:
Decorative laminates
Picnic wares
Buttons
Polyester resin
Rigid Heat resistant Chemical resistant Brittle Safe working temperature 95 degrees C Themoset
Uses:
Castings
Used in lay up process of GRP for boat hulls
Chair seats
Epoxy resin
Rigid Clear hard Tough Chemical resistant Safe working temperature 80-100 degrees C Thermoset
Uses:
Adhesives
Surface coatings
Encapsulation of electrical components
Cardiac pacemakers
Natural rubber (polyisoprene)
High tensile strength Good hardness Tough Electrical insulator Good cold resistance Elastomer Low elongation
Butadiene rubber (BR)
Tough
Excellent wear resistance against friction
Good thermal resistance against friction
Electrical insulator
Elastomer
Uses:
Vehicle tyres Shoe soles Toys Conveyor belts Water and pneumatic hoses
Neoprene (polychloroprene rubber)
Good thermal resistance Toughness Good oil and chemical resistance Excellent weather resistance Good abrasion resistance Electrical insulator Elastomer
Silicone
Good flexibility at lower temperatures Poor abrasion resistance Good thermal resistance and resistance to temperature extremes Good weather resistance Good lubricating qualities Electrical insulator Elastomer
Natural rubber (polyisoprene) uses
Automotive industry - tyres Tubes Hoses Gaskets Belts Balloons Toys Footwear
Neoprene uses
Wetsuits Laptop cases Industrial wire insulation Shock absorber seals Hose covers Transmission belts Door seals
Silicone uses
Flexible ice cube trays Bakeware Cooking utensils Seals for refrigerators Machinery lubricant Sealants Mould making Tubing for drug delivery systems Lubricants for prosthetics
General properties of polymers - for justifying questions
Tough - impact resistant
High strength to weight ratio
Waterproof
Chemical resistant
Heat proof
Long time to degrade
Some can be recycled
Can be pigmented
Thermoplastics examples
LDPE HDPE PP HIPS ABS PMMA Nylon uPVC PVC
Thermoset polymer examples
Urea formaldehyde
Melamine formaldehyde
Polyester resin
Epoxy resin
Elastomer examples
Natural rubber (polyisoprene)
Butadiene rubber
Neoprene (polychloroprene rubber)
Silicone
Issues with traditional polymers
From crude oil - non-renewable resource
Risk of environmental damage to marine life when sourcing and transporting crude oil
Long time to decompose and contributes to landfill
Thermoplastics can sometimes be recycled but thermoset plastics can’t
