Impact of luminescent yarns structure on light emission

This study investigates and discusses the structure of the luminescent phosphorescent multifilament yarns to determine the effect of their external and internal structure geometry on the magnitude of light emission. The polyester luminescent multifilament yarns with the flat, textured, air textured and wraped were analyzed and compared in terms of their structure and the intensity of light emission. The light emission was evaluated based on the wavelength that corresponded to the maximum emission light signal. The signal was determined from the values of the emission light signal of all wavelengths spectrum at zero time for all measured luminescent multifilament yarns. Geometrical properties of luminiscent multifilament yarns (number of fibrils, multifilament diameter and diameter variability, number of entanglements), as well as individual fibrils (fibril fineness, fibril equivalent diameter, and shape factor) were measured and calculated to analyze their effect on light emission. The assumption that light emission increases with increasing yarn count and yarn diameter was not confirmed. In relation to the type of yarns, the geometry of the fibers in the yarn is decisive in terms of fibril fineness and area of ​​fibril cross-section.