The frist report on film blowing instabilities was presented by ast in 1974. Later on, Han and Shetty observed that lowierng melt temperature leads to more stable bubble formation. The first theoretical study of bubble stability was shown in the work of yeow for an isothermal film blowing process considering Newtonian polymer melts. Comprehensive experimental studies were presented by Kanai and White, Minoshima and white and Yamane who revealed that film blowing stability for low density polyethylene is higher than that for linear low densitybpolyetylene. In 1988, Cain and Dene extruded Yeow’s work to a viscoelastic upper convected Maxwell fulid. They found that the stability decreases in the following order LDPE > HDPE > LLDPE > PP .bulter(2000). In his work.