Abstract
This paper presents practical knowledge about dissolving and spinning cellulose in the NMMO-H2O system described in the Kodak and Akzona patents. From the highly hydrated NMMO commercialized by Texaco and a viscose pulp with an average polymerization degree of 700, we made true solutions in two stages: swelling of the cellulose and evaporation of the largest part of the water in a mixing-kneading device under vaccum, and dissolving in a twin-screw extruder with degassing sections. The depolymerization was controlled by antioxidants. The spinning of solutions with 10 or 20% cellulose is on line with the dissolving operation. After drawing in air, the filaments are plunged into water, which separates the NMMO from the cellulose. The initial modulus of the filaments depends on the drawing ratio. The best value measured (about 15 N/tex) is comparable with values from commercial high modulus viscose fibers. The breaking strength is still insufficient because of microbubbles, which will be removed in the future by means of a more efficient degassing of the solutions.
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