抄録
Blown bubble tubes of high molecular weight high density polyethylene were formed using the apparatus with an inner cooling mandrel and an outer water cooling ring, and the strain rates of the blown bubble forming process were obtained. From the results, it is found that the strain rate in the flowing direction decreases in the early stage of blowing up, and then, through minimum, it increases. The minimum value of the strain rate in the flowing direction decreases with increasing take-up velocity, and it becomes negative at a take-up velocity of 10m min-1. This result shows that not only elongational viscosity, but also elasticity is important in the blown bubble process.
