Fig. 6From: Transparent Polyurethane Nanofiber Air Filter for High-Efficiency PM2.5 CaptureTPU fiber membrane contact angle characterization. a–f Testing the contact angle of different concentrations of TPU fiber membranes using 5-μL droplets. g Contact angle of different concentrations of TPU fiber membrane. h–i Droplets on the surface of fibers of different diameters.Back to article page