Three types of Plastics:
- Thermoplastics- Can be reheated and reshaped as they have loose monomer chains, can be recycled, coloured pigments can be added to make it more aesthetically pleasing.
- Thermosets- Undergo a chemical change so permanetly rigid, cannot be reheated or reshaped as it forms rigit cross links, e.g spoons.
- Elastomers- Can be distorted under pressure but will return to thier original shape.
The Properties of Plastics are:
- Electrical and thermal insulators
- Good strengh to weight ratio
- Good atmospheric and chemical corrosion resistance
- They are lightweight
- Fairly low melting pionts (thermoplastics)
- They can be self-coloured, opaque, translucent or transparent
BS- High impact, scratch resistant, lightweight durable- Kichen products, mobile phone cases, safety helmets, toys- Injection moulded.
PC- Polycarbonate- Good chemical resistance, expensive, very tough, high melting piont- Protective shields, safety hats and glasses, telephones, hairdrying bodies- Injection moulded.
PP 5- Polypropylene- Lightweight, food safe, good impact and chemical resistance- Food containers, medical equipment, string and rope- Injection moulded.
HIPS- High Impact Polyethylene- Good impact resistance, good strengh and stiffness, lightweight- Toys and refrigerator linings- Vacuumed formed.
PMMA 7- Acrylic- Foof safe, tough, hard, durable, easily machined- Light units, illuminated signs, lenses for car lights, Hand/CAM cut.
HDPE 2- High Density Polyethylene- Good stiffness, good chemical resistance- Crates, bottles, buckets, bowls- Injection Moulded.
LDPE 4- Low Density Polyethylene- Lightweight, low stiffness and rigidity,…