# What's the difference between “conversion” in condensation polymerization and in radical polymerization?

The conversion in condensation polymerization is defined as the fraction of functional groups reacted,

$$p=\frac{[M]_0-M}{[M]_0}$$

while in radical polymerization it's defined as the fraction of monomer that has reacted.

Why is it not the same thing?

• Consider dimers. All the monomer has reacted, but the chain length is short. – MaxW Dec 7 '15 at 18:04
• It is the same thing as long as you have monomer with one double bond (functional group) in radical polymerization. – Mithoron Dec 7 '15 at 18:09