Dynamic wetting of fibers observed in an environmental scanning electron microscope

Wetting is an important characteristic of textile materials in many applications. Microscopic observations of dynamic wetting of untreated and oxygen plasma treated polypropylene fibers on the environmental scanning electron microscope (ESEM) are explored in this study. The relative humidity in the ESEM chamber is raised to 100% by controlling the specimen's temperature and the chamber pressure to produce water condensation on the fiber surfaces. Dynamic wetting, that is, the formation, spreading, and coalescence of water droplets on fiber surfaces, is observed and recorded in real time. Contact angles are measured from the ESEM images, which reveal the dynamic wetting of textile fibers on a micron level.