Question

If Mw is the weight average molecular weight and Mn is the number average molecular weight of a polymer, the polydispersity index (PDI) of the polymer is given by:

• A. $\frac{{\overline{M}}_n}{M_w}$
• B. $\frac{{\overline{M}}_w}{{\overline{M}}_n}$
• C. ${\overline{M}}_w\times {\overline{M}}_n$
• D. $\frac{1}{{\overline{M}}_w\times {\overline{M}}_n}$

Answer 1

The correct option is B

$\frac{{\overline{M}}_w}{{\overline{M}}_n}$

Polydispersity index , PDI gives an idea about homogenity of a polymer .

$PDI=\frac{weightaveragemolecularmass\left(\overline{M_w}\right)}{numberaveragemolecularmass\left(\overline{M_n}\right)}$