SA key term in the coefficient of variation is MW
MN
. This term is known as the polydispersity
index. For the coefficient of variation to be real (as it must), the polydispersity index must be
greater than or equal to one. When it is equal to one, the coefficient of variation is zero which
means that the distribution is monodisperse. For all real polymers it is greater that one and the
amount that it is greater than one is a measure of the polydispersity of that polymer.