Nylon 66 Nanofiber Sheets Prepared by Carbon Dioxide Laser Supersonic Multi-drawing

Carbon dioxide (CO2) laser supersonic drawing is a new technique for preparation of nanofibers in a vacuum chamber using a CO2 laser and a supersonic air jet formed directly below the fiber supply orifice. In this study, we have applied a CO2 laser supersonic multi-drawing method to nylon 66 to produce nanofiber sheets. A fiber of 182 μm in diameter was drawn at a drawing speed of 223 m s-1 and a draw ratio of approximately 1.3×105 to obtain a nanofiber sheet having 25 cm length, 17 cm width, 61.5 μm thickness, and an average nanofiber diameter of approximately 0.5 μm. The nanofiber sheet exhibited two melting temperature (Tm), 259°C (Tm1) and 270°C (Tm2). Tm2 is approximately 10°C higher than the Tm value of nylon 66 at usual. The sheet showed no drastic fiber shrinkage during heating, and the fiber form was held even at the temperature of the usual melting temperature or higher.