Steadily Controllable Anionic Ring-Opening Polymerization of ε-Caprolactam at High Temperature with a Low Mg-Initiator Dosage To Produce Polyamide 6 for Direct Melt Spinning

(220 °C), simultaneously maintaining high conversion (ca. 95%) and a quasi-living character. The cyclic dimer residual was restricted to an unprecedented level (<0.01 wt %). The proposed simple system is more efficient and greener than the traditional HP and AROP techniques, offering a promising approach for producing PA6 fibers via direct melt spinning.