▎ 摘　　要

Mechanical properties of polyacrylonitrile (PAN) polymer can be significantly improved by the incorporation of graphene nano-sheets of different sizes. The graphite was exfoliated to graphene using sonic tip in the presence of N-methyl pyrrolidinone (NMP) as a solvent. Exfoliated graphene was separated from unexfoliated graphitic crystallites using selected speed (rpm) of centrifuge for specific time. The exfoliated graphene nano-sheets were classified into two different groups on the basis of flake size, (i.e. 1 mu m and 3.5 mu m). Then these graphene sheets were incorporated into PAN to study the effects of their flake size on mechanical properties. Different mechanical properties such as Young's modulus, ultimate tensile strength (UTS) and elongation at break (dL at break) were studied. Young's modulus and UTS improved more than 45 % and 25 %, for 3.5 mu m graphene flake size respectively. While more than 40 % and 21 %, improvement in modulus and UTS for 1 mu m graphene sheet were observed respectively.