Question

The $P$(poly) Dispersity Index $\left(PDI\right)$ of a polymer is: $(\overline{M_w}=$ weight average molecular mass and $\overline{M_n}=$ number average molecular mass).

• A. the product of $\overline{M_n}$ and $\overline{M_w}$
• B. the sum of $\overline{M_n}$ and $\overline{M_w}$
• C. the difference between $\overline{M_w}$ and $\overline{M_n}$
• D. the ratio between $\overline{M_w}$ and $\overline{M_n}$

Answer 1

Answer: (D)

the ratio between $\overline{M_w}$ and $\overline{M_n}$

The ratio between weight average molecular mass $\left(\overline{M_w}\right)$ and number average molecular mass $\left(\overline{M_n}\right)$ of a polymer is calledd Poly Dispersity Index (PDI).

$PDI=\frac{\overline{M_w}}{\overline{M_n}}$

It is always greater than $1$, Polymers with PDI greater than $1$ can be synthesized.