Study on die-swell of BTDA-TDI/MDI copolyimide spinning solution

摘要

In this paper, the die-swell behavior of tetracarboxylic acid dianhydride (BTDA)-toluylene diisocyanate (TDI)/diphenylmethane diisocyanate (MDI) copolyimide solution was studied on a capillary-rheometer by photographic method. Extrusion die-swell ratio (B) was measured under different die specification and extrusion conditions. Die length/diameter ratio (L/D) was varied from 1 to 9. Extrusion conditions included temperatures of solutions from 15°C to 60°C, extrusion pressures from 0.2Mpa to 0.5Mpa, and filter gauze layers. The results showed that B increased with the increase of pressures, but decreased with the increase of temperature, the die length/diameter ratio and the number of filter gauze layer.