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Rubber in Car Tyres

Rubber in Car Tyres. Mr. Reilly. Context - Uses. Many purposes e.g.: Tyres bowling balls Balloons Insulation (electric and thermal) Bungee chords B ouncy balls Rubber bands. Context - vulcanization. To make plastic less malleable it is vulcanized

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Rubber in Car Tyres

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  1. Rubber in Car Tyres Mr. Reilly

  2. Context - Uses • Many purposes e.g.: • Tyres • bowling balls • Balloons • Insulation (electric and thermal) • Bungee chords • Bouncy balls • Rubber bands

  3. Context - vulcanization • To make plastic less malleable it is vulcanized • Usually done by heating in high pressure with sulphur • This bonds the chains together and leaves them less room to stretch

  4. context- abundant • Easily tapped from rubber trees • Renewable resource • Being used less as it is replaced by synthetic rubber

  5. Context/property- reusable • Rubber can be ‘melted down’ and reused • Breaks the sulphur bonds from vulcanization • Then re-vulcanized to the desired extent • Renewable resource

  6. Macroscopic Property- Inert/un-conductive • Polymer chains have full outer rings and do not easily react • Useful in tyres which would break if they corroded • Also no charge carrying particles i.e. delocalised electrons or ions so very poor conductor • Used in electrical and thermal insulation as it is malleable and resistive to heat and electricity

  7. Context – vulcanization;diagram • Vulcanisation is cross-linking the chains of hydrocarbons, making them less easily stretched.

  8. Macroscopic Property- High Friction • Long chains of hydrocarbons are arranged in a random way • High surface area to volume ratio created by uneven surface where many chains are curled over each other

  9. Macroscopic Property- Stretchy • Long chains can be ‘untangled’ to become longer by pulling on them before returning to their original shape when released • The expansion they can undergo is limited by reacting with sulphur in vulcanization. • This is because the sulphur bonds the chains together so they can not be untangled as easily

  10. Black dots are cross-linked hydrocarbons held together by sulphur Macroscopic Property- Stretchy;Diagram Un-stretched rubber Stretched rubber

  11. Macroscopic Property- Malleable before vulcanization • Long chains able to slide over each other. • Easily bent and manipulated plastically, as it is vulcanized more, plastic deformation becomes more difficult and elastic deformation becomes more common. • When vulcanized enough it becomes so stiff that any bending requires very large force and is plastic rather than elastic with the rubber being torn/smashed

  12. Macroscopic Property- Malleable before vulcanization • Only force keeping the chains together before vulcanization is the weak van der waals forces which can easily be broken • Chains easily change shape and slide over each other • Changed by vulcanization ‘ties’ chains together

  13. Macroscopic Property- high grip • Malleable nature- a high surface area against the ground • Long chains randomly arranged over each other gives uneven surface • Uneven surface gives high surface area to volume ratio • Useful for tyres especially

  14. Car tyre undergoing elastic deformation as it gains more grip when starting a drag race to gain more grip Macroscopic Property- high grip;diagram

  15. Macroscopic Property- resistant to tearing and plastic deformation when vulcanized • Vulcanisation makes rubber far stronger and less Malleable • still allowing elastic deformation before snapping • Due to strong covalent bonds • Natural rubber in car tyres is strong but is still reinforced to ensure they do not puncture often • Many strong covalent bonds between carbon atoms must be snapped to tear

  16. Tyres have large ridges built into them to increase the surface area and maximise friction and therefore grip, especially over smooth surfaces Macroscopic Property- tough and high grip

  17. Macroscopic Property- most elastic after small amount of vulcanization • Under no vulcanization chains are easily shifted and have no urge to return to original shape • When vulcanized slightly chains only ‘fit’ in certain shapes so will be most willing to return to those shapes • When vulcanized more changing the shape requires the breaking of the strong sulphur bonds

  18. conclusion • Varied properties allow for many uses • Long polymer chains held together by sulphur in most cases • In car tyres being slowly replaced by synthetic rubber

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