Tensile stress in jets of viscoelastic fluids. II

A viscoelastic fluid jet is treated as a moving infinite string under slowly varying tension. When the system is subjected to a sinusoidal point vibration, the resulting wave form enables the tension to be determined along the jet. The total tension is composed of a surface reaction and an internal, decaying tension. The surface reaction may be calculated from the surface tension of the jet fluid and the radius of the jet. Data for 1.4 and 1.7% carboxymethylcellulose water solutions are presented for three different jet radii and for solution temperatures of 5, 25, and 35°C. It is found that the observed tensions approach the calculated surface reaction far from the nozzle. The rate of decay is a function of concentration and temperature. The internal tension for a 1.7% solution at 25°C. was observed to decay from about 8000 to 500 dynes/cm.2 in 200 milliseconds. Relaxation times of 0.27 sec. for 1.4% and 0.32 sec. for 1.7% solutions at 25°C. describe the internal tensile properties between 40 and 200 milliseconds after ejection.