Explain why the melting and glass transition temperatures of a polymer depend on its molecular weight....

Explain why the melting and glass transition temperatures of a polymer depend on its molecular weight. Your answer should include reference to free volume theory. (12)

Expert Solution

The melting and glass transition temperatures of a polymer increases with increasing it's molecular weight.

This can be explained on the basis of free volume theory.

Free volume is defined as the empty space between the polymer chains in polymer molecules. It is due to the presence of free volume the mobility of the polymer segments increases which leads to decrease the melting and glass transition temperatures consequently .

Higher the free volume lower will be the melting and glass transition temperatures .

In a given volume of polymer, the mobilty of chain segments is higher for the low molecular weight polymer as compare to that of high molecular weight polymer. Therefore it can be said that the free volume decreases with increasing molecular weight of the polymer.

Thus melting and glass transition temperatures increase with increasing molecular weight.

queen_honey_blossom answered 2 years ago

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