• Old cars made of metal, canvas, wood and rubber. No plastic
• New car today's made out of plastics. Polycarbonate, acrylic, PVC, fibre glass etc.
• Are synthetic
• Chemical factories made from crude oil or natural gas.
• Heat oils to separate different oils, some go to make petrol
• Ethylene
• Polyethylene
• Different kinds can be produced from one oil
• Cut into pellets (polymer)
• Types of plastics: thermoplastics and thermosets
• Thermoplastics melt when heated
• Thermoset plastics don't melt when heated. It breaks down when heated.
• Thermoplastics
• PET, polyethylene , PVC, polypropylene,
• Plastics can be mixed to make alloys ( ABS )
• Physical properties of plastics
• Tensile strength - nylon very good, specially for guitars
• Impact strength - isod impact test. Zenoid good for impact resistance, polypropylene
• Stiffness - resistance to bending. Zenoid was best in the test. PVC pipes
• Hardness - resistance to scratching and indentations.
• Friction - physical property in some products, eg. Nylon low friction for gears.
• Thermal properties - how the material behaves at different temperatures. Acrylic is good for bending stuff.
• Thermoplastic have a lower melting point.
• Melt flow, how easy of flows when melted.
• Electrical properties - poor conductors, excellent insulators
• Chemical properties - plastics resist corrosion. PVC can be dissolved by acid. Petrol containers are very high density polyethylene. Sunlight can effect it. Paintability. Flame treatment now used so paint can be put on polyethylene.
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