Ultrasonic energy-assisted coloration of polyurethane nanofibers

Herein, we first time present our research on ultrasonic dyeing of polyurethane (PU) nanofibers. The PU nanofibers were fabricated by electrospinning process and were subsequently dyed following exhaust method using sonication. The two disperse dyes selected were a low-energy disperse dye (CI Disperse Blue 56) and a high-energy disperse dye (CI Disperse Red 167:1). The ultrasonic energy was used to achieve higher color build-up on PU nanofibers. The temperature/time (T/T) diagram of proposed dyeing process has been suggested; dyeing time and dyeing temperature were optimized. Color build-up properties (measured in terms of K/S values), dye fixation (%), and color fastness properties were studied in detail. The samples were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and mechanical strength measurements. The results show 70 degrees C and 40 min as optimum dyeing temperature and time, respectively. The SEM, FTIR, and XRD results did not show any significant effect of ultrasonic dyeing on morphology, chemical, and crystallographic structure of PU nanofibers. Color fastness results revealed excellent light fastness, very good washing, and hot pressing fastness of both dyes.