Study on dry spinning and structure of low mole ratio complex of calcium chloride-polyamide 6

摘要

Polyamide 6 (PA 6) filaments with initial modulus around 48 GPa were produced by dry spinning from low mole ratio (MR) complex of calcium chloride and high molecular weight PA 6 (CaCl_2-PA 6) in formic acid. From the results of XRD, DSC, FTIR, and SEM, the complexation of CaCl_2-PA 6 in the MR range of 0.15-0.3 was efficient. The spinnability of the complex solution was excellent, which allowed a maximum draw ratio of 14.4 for as-spun fibers. After decomplexing and annealing, the birefringence of drawn fiber could reach around 0.08. Porous structure was found in fibers spun from formic acid-chloroform cosolvent but not observed by using pure formic acid. When MR of CaCl_2/PA 6 exceeded 0.3, some irregular particles formed on the fiber surface due to the recrystallization of CaCl_2. However, fibers with smooth surface could be obtained when the MR decreased to 0.15. During the process of decomplexing in ethyl alcohol, an axial shrinkage of drawn fibers in a relaxed state was observed. It turned out that this shrinkage could be avoided by decompexing the fibers under tension.