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Why is the flow behaviour or viscosity important in the case of polymer?

  1. Mar 31, 2005 #1
    Why is the flow behaviour or viscosity important in the case of polymer?

    This question is given when we had lecture about flow behaviour, viscosity, and rheology.

    Thanks a lot!
     
  2. jcsd
  3. Apr 8, 2005 #2
    Viscosity is an important characteristic of polymers because it gives an insight to the structure and in turn, the degree of bonding in the structure, and how well the structure is formed. Flow behaviour determines the processibility of the polymer into different products like plastics, elastomers etc It's atill an important research area as to how to manipulate polymers for various applications.

    E.g. of such applications http://www.phy.bris.ac.uk/research/polymers/flow.html
     
  4. May 14, 2005 #3
    Mr.cute, are you a student taking course MAT705 in Queen Mary College? I meet the same question in the exam.
     
  5. May 14, 2005 #4
    Well, in a physical chemistry lab this semester we dissolved polystyrene in toluene and measured the viscosity, from which we were able to derive the molecular weight of the polymer from the relationship n = M^a (where n is the viscosity coefficient, M was the molar mass and a was a constant equal to about ~0.75 if I remember correctly. We measured the molecular weight to about 100,000 g/mol, which was pretty accurate.

    As atomic blast suggested, the viscosity is influenced by how tightly "coiled" the molecule is - that is what the consant "a" is a measure of.
     
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