Effect of germanium particle size on the negative air ion release and antimicrobial performances of germanium–polyamide 6 composite fibers

Germanium–polyamide 6 (Ge-PA6) fibers A, B and C containing germanium particles with sizes of D50 = 0.2, 2 and 7 μm were prepared using the melt spinning method. The effect of germanium particle size on the morphologies, mechanical properties, negative air ion (NAI) release and antimicrobial efficiencies of the two kinds of fibers were compared and analyzed. The NAI release and antimicrobial mechanisms of the Ge-PA6 fibers were also discussed. Results indicated that the germanium particles dispersed well inside the PA6 fiber substrate in the range of 1–3 wt%, and smaller particles help the fiber to obtain better diameter evenness and mechanical performance compared with larger ones. The stronger extranuclear electron activity and electrostatic voltage along the C-axis allow the fiber that contains smaller germanium particles to produce more NAIs compared to that containing larger particles. Some 780 and 1587 ions/m 3 of NAIs could be produced by fiber A under the circumstance of 35°C and 40 N extrusion force when the germanium concentration was fixed at 3 wt%. The excellent NAI release property of the Ge-PA6 fiber endows it with inspiring antibacterial activity against S. aureus and C. albicans with a 12 h bacteriostasis rate of more than 90% at human body temperature. These results indicated Ge-PA6 fibers have great application potential in apparel and medical textiles.