Polymers: Properties, Thermosoftening & Thermosetting

PROPERTIES: - Low density poly(ethene), LDPE. Flexible, unreactive, can be made into films. Used in Most carrier bags, bubble wrap (polymer chains are branched and this means that the molecules are arranged randomly) - High density poly(ethene), HDPE. Strong, flexible, resists shattering, resists chemical attack. Used in plastic bottles, pipes, buckets (less branching of the polymer chains, so the molecules line up much more closely) THERMOSOFTENING: - melt when they are heated ∴ can be recycled - do not have covalent bonds between neighbouring polymer molecules, so the molecules can move over each other when heated and the plastic melts. THERMOSETTING: - tend to char and burn when heated - resistant to much higher temperatures than thermosoftening plastics - used to make electrical plugs, which must not melt, even if there is a malfunction and the wiring inside gets hot (due to the covalent bonds holding the neighbouring polymer chains together)