LensAramid fibers
Figure 1: Continuous single-step process for aramid spinning solutions.
Aramid spinning solutions

Aramid fibers are typically wet-spun from a solution of polymer, such as poly(p-phenylene terephthalamide) (PPTA), in concentrated sulfuric acid. The dissolving process is exothermic, and the thermal energy released helps to melt and dissolve the polymer. The polymer solution is viscous and non-Newtonian. The requirement is to create a degassed solution with a controlled polymer concentration and a homogeneous composition, so that dope exiting the spinneret will coagulate rapidly into fiber and freeze the orientation of the macromolecules. With the right technology, the dissolving step can be carried out in a single continuous processor, thus minimizing investment costs and space requirements (Figure 1).

During the homogenization step, the large volume of the LIST KneaderReactor ensures a constant and uniform polymer concentration by averaging out any short-term fluctuations in concentration, and any local inhomogeneities. Compared to the use of extruders, LIST KneaderReactor technology can achieve a higher polymer concentration in the spinning solution. This yields filaments with a higher degree of crystallinity in their molecular structure, and hence improved physical properties. Strength, modulus, elongation and temperature resistance all improve with the LIST process.

LIST KneaderReactor Technology:

  • Offers high flexibility in terms of capacity and product grades
  • Delivers excellent product quality
  • Is reliable, economical, safe, and environmentally sound