[tone999]

Q. Write the chemical formulae for polyethylene, polyproplylene, PVC and polystyrene and on the basis of their chemical features describe why they exhibit different glass-transition temperatures.

A. Polyethylene   = (CH2)n
    Polyproplylene = (C3 H6)n
    PVC               = (C2 H3 Cl)n
    Polystyrene     = (C8 H8)n

That bit is fine i think?

But why they exhibit different glass-transition temperatures?

Is this because of the different groups eg. aliphatic, side groups, polar groups etc.
Any help would be much appreciated

[DrCMS]

I'd draw out the structures more clearly then think about what the structures mean in terms of packing amd movement of the different polymer chains.