Thermosetting polymers and elastomers Flashcards
(20 cards)
Form of supply of epoxy resins
Supplied as two parts:
- One resin
- One hardener
They combine to make an extra-strong adhesive
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Properties of epoxy resins
- Strong, tough and rigid
- Durable
- Good chemical and thermal resistance and stability
- Good electrical insulator
- Good adhesive
Where epoxy resins are used
- Cheaper and faster than welding (metals and plastics)
- General-purpose adhesives
- Rigid foam
- Laminates
- Container linings
- Waterproof coatings
- Panels
Form of supply of polyester resins
Supplied as two parts: - One resin - One hardener They combine to make an extra-strong adhesive - It sets clear and smooth
Properties of polyester resins
- Viscous
- Low density
- Adhesive
- Strong odour and toxic fumes
- Water-resistant
- Good wear resistance
- Heat resistance and a good insulator
- Strong and tough
- Weaker than epoxy resin
Uses of polyester resins
- Adhere body panels of vehicles eg boat hulls, motor panels, aircraft parts
- Packaging
- Waterproofing and encasing items
- Laser printer toner
- Combined with fibreglass to make GRP (eg for skis)
- Fishing rods
How does urea formaldehyde come?
- Limited colours
- Opaque
- Smooth finish
Properties of urea formaldehyde
- Very high tensile strength
- Low water absorption
- High surface hardness. Scratch resistant
- Brittle and rigid
- Very good insulator
- Heat resistant
- Easily injection moulded
Uses of urea formaldehyde
- Plug sockets and electrical appliances and fittings that are safe to use
- -> knock-resistant (hard/tough); insulator
- Adhesive for binding interior plywood and particleboard
- Treating textile fibres (better wrinkle/shrink resistance, higher surface hardness for coating)
Properties of melamine formaldehyde
- Brittle
- Food-safe, dust-free surface (hygienic)
- Printable surface
- Excellent insulator
- Low water absorption
- Can be cast and moulded
Similar to urea but - Better moisture and heat resistance
- Harder and stronger (one of the hardest plastics)
Appearance of melamine formaldehyde
- Very smooth surface finish
Uses of melamine formaldehyde
- Laminates (smooth surface and hygienic)
- Electrical plugs, sockets and light switches
- Pan handles
- Adhesive for particleboard or plywood
- Household crockery/tableware eg glasses, plates, cups, bowls
Source of rubber
Latex from rubber tree
Forms of supply of rubber
- Bars
- Sheets
- Tubes
Typical properties of rubber
- High elasticity
- Contracts with heat
- Malodour
- Water resistant
- Abrasion resistant
Common applications of rubber
- Tyres and tubes for vehicles eg car, bike, lorry
- Shock absorbers for buildings
- Seals
- General goods eg balloons, rubber bands
Source of neoprene
Polychloroprene, which comes from crude oil and chlorine
Forms of supply of neoprene
A synthetic rubber
- Sheets
- Foam
- Extruded neoprene
Properties of neoprene
- Resistant to heat, cold, flame, oil
- Resistant to weathering and chemicals (inert)
- Bonds well with other materials
- Flexible and holds its shape over time
- High tensile strength
Applications of neoprene
- Corrosion-resistant coatings
- Power transformers (fire resistant)
- Safety equipment eg gloves
- Padding and packaging
