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 (CaCl₂) was used as a modifier to regulate the crystallization rate and drawing performance of PA66. With the increased presence of CaCl₂, the viscosity of PA66/CaCl₂ increased, and the crystallization rate was significantly suppressed. At 5 wt % CaCl₂, 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 Ca²⁺ 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.