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A heterogeneous batch of polyethlene can have a PDI of 1? true or false?

A heterogeneous batch of polyethlene can have a PDI of 1?

true or false?

Engineering   Chemical-Engineering   
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Answer #1

Molecular weights in a polymer are not fixed rather molecules sizes are statistically distributed depending on the degree of polymerization.

There are two ways to define the average molecular weight of the polymer.

1] The Number average molecular weight Mn, where

,

  

fi = Fraction of all molecular chains having a molecular weight Mi .

2] The weight average relative molecular weight Mw

wi = weight fraction of polymer chains having molecular weight Mi.

The ratio Mw/Mn = The polydispersity index (PDI)

The value of PDI is always greater than 1.

Hence, the given statement is false.

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