抄録
The capillary jet (die swell) method for the measurement of normal stresses has been studied in terms of many variables and rheological descriptions. The present paper deals with diameter effect first reported by Powell and Middleman, and proposes that the most important parameter is the ratio of the inertial force to the elastic stress. When this parameter is greater than 1, the momentum balance equation proposed by Metzner et al. gives reasonable values for the first normal stress difference. When this parameter is less than 1, the diameter effect begins to appear and the capillary jet method is not applicable. A more pronounced diameter effect corresponds to smaller values of this parameter.
