Sheath-core microporous polyamide 6 fibers via in situ foaming and bicomponent melt spinning for thermal insulation

The development of thermal insulation materials that simultaneously integrate lightweight characteristics, mechanical robustness, and wearing comfort remains a formidable challenge. In this study, a facile strategy was proposed for the continuous fabrication of sheath-core microporous polyamide 6 fibers (MPA6 fibers) via in situ foaming and bicomponent melt spinning. By regulating the content of the foaming agent masterbatch (FAM) and the drawing ratio, the resulting MPA6 fibers achieved a density of 0.90 g cm^-3 (21.1% lower than that of PA6 fibers) while maintaining a tensile strength of 280.4 MPa. The fabrics (MPAW and MPAK fabrics) fabricated from these fibers demonstrated enhanced thermal insulation performance under both hot and cold conditions, indicating their potential for personal thermal management. Notably, the MPAW fabric combined high air permeability (307.7 mm s^-1) with good durability, which is beneficial for practical applications. This fabrication strategy not only provides a feasible approach for developing lightweight and thermally insulating textiles, but also offers new possibilities for the design of high-performance multifunctional fibers.