Explain the preparation of polyacrylonitrile and also write down its uses.

(N/A) Preparation: The addition polymerization of acrylonitrile $(CH_2=CHCN)$ in the presence of a peroxide catalyst leads to the formation of polyacrylonitrile. The reaction is as follows:
$nCH_2=CHCN \xrightarrow{\text{Polymerization, Peroxide catalyst}} [CH_2-CH(CN)]_n$
Uses: Polyacrylonitrile is used as a substitute for wool in making commercial fibres such as orlon or acrilan.