Crystallization Regulation Determined Spinnability and Mechanical Properties toward PA66/Calcium Chloride and Its Fibers.

Strong hydrogen bonding and the fast crystallization rate of polyamide 66 (PA66) bring difficulties in the fabrication of high-performance PA66 fibers. In this work, calcium chloride (CaCl) was used as a modifier to regulate the crystallization rate and drawing performance of PA66. With the increased presence of CaCl, the viscosity of PA66/CaCl increased, and the crystallization rate was significantly suppressed. At 5 wt % CaCl, the crystallinity decreased from 31.36 to 19.52%, indicating a notable inhibition effect. The isothermal FTIR mechanism studies elucidated that a blueshift of the N-H stretching vibration can be observed, which resulted from the complexation between Ca and the oxygen atoms on the amide groups disrupting the original hydrogen bond. The inhibition of hydrogen bonds promotes the fabrication of PA66 fiber with a draw ratio at 3.5 and a breaking strength at 5.16 cN/dtex. This work provides an effective way to enhance the spinnability and drawability of PA66 fibers.