Thermoplastic polymer and Diamond

Discussion in 'Homework Help' started by Hello, Jan 3, 2009.

  1. Hello

    Thread Starter Active Member

    Dec 18, 2008
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    The modulus of diamond which is a form of carbon is approximately 1000 GPa. The modulus of a typical thermoplastic polymer which is primarily a long-chain molecule based on carbon chains is typically 1 - 2 GPa. Explain the difference in modulus values in terms of bonding in the material, the molecular structure and the arrangement of molecules in the solid material.



    Any help is greatly appreciated.
     
  2. hgmjr

    Moderator

    Jan 28, 2005
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    Is this a homework assignment? If so, I need to move it into the homework section.

    hgmjr
     
  3. Hello

    Thread Starter Active Member

    Dec 18, 2008
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    Its a test Question!
     
  4. hgmjr

    Moderator

    Jan 28, 2005
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    What answer did you give to the test question?

    hgmjr
     
  5. Hello

    Thread Starter Active Member

    Dec 18, 2008
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    Thermoplastic polymer - held together partly by van der waals forces and partly by covalent bonds.
    -Has long spaghetti-like chains of carbon atoms.

    Diamond - Covalent bond
    - each C atom has four covalent bonds with four other carbon atoms
     
  6. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
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    Your answer is true but how does your answer make diamond stronger?

    Diamond is a crystal structure with tetrahedral symmetry.

    The structure and shape of the crystal is fixed and regular. It is held together by covalent bonds. This gives it its strength.

    Polymers have variable chain length and thus indeterminate structure. Whilst the inter molecular bonds are covalent the intra molecular bonds are only weaker Van der Walls bonds.

    So diamond is a strong crystal held together by a regular array of strong bonds.
    Polymers are an irregular assemblage of molecules held together by weak bonds.
     
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