DMAC purification

DMAC is mainly used as a solvent, for example, as a solvent for solution spinning of an elastic polyurethane block copolymer and a solvent for producing hollow fibers, which are known under the trademarks Spandex(R) or Lycra(R).

In order to be able to obtain high quality fibers by solution spinning, some specifications are required for the DMAc used here with a water content of <100 ppm, a pH between 6.5 and 7, and a specific conductivity of <0.6 μS/cm, or <0.2 μS/ Cm. Pure DMAC produces a significant electrical conductivity by its impurity content, such as an acid, particularly acetic acid; and a salt, especially an amine salt of acetic acid. The specification of pure DMAC relative to pH and conductivity corresponds to an acetic acid content of less than 50 ppm by weight.

A DMAC that meets these specifications is called a pure DMAC.