Study on die-swell of meta-aramid solution

摘要

Die-swell is a unique phenomenon for polymer solution when it was extruded from a die. This was resulted from the viscoelastic properties of polymer solution. The extent of die-swell was usually expressed by extrusion die-swell ratio (B). The extrusion die-swell ratio (B) of meta-aramid solution was studied on a Capillary-Rheometer by gravimetric method in this paper. The die-swell ratio for meta-aramid solutions was determined under different temperature, capillary L/D, filter layers, pressure and other conditions so as to investigate the effects of die geometry and extrusion conditions on the die swell behaviour of the solution. The results showed that B of the solution increased linearly with increase of pressure; when pressure and temperature were constant, B decreased nonlinearly with increase of the die length/diameter ratio; when pressure, temperature and L/D were constant, B decreased with increase of filter layers; when other conditions were constant, B decreased with increase of temperature.