The initial afterglow intensity, breaking strength, breaking elongation and spinnability of SMSED-PP luminescent fiber samples are listed in Table 1. Fig. 1 shows the afterglow decay curve of SMSED phosphors and SMSED-PP fibers mixed with phosphors of different contents. Additionally, as tested in the dark room, the afterglow decay time of each sample from the initial intensity to 0.32 mcd/m2, which is the minimum intensity and can be observed by human eye, is about 7 h. In other words, the afterglow life has no distinct connection with the content of SMSED. As shown in Table 1 and Fig. 1, the initial afterglow intensity of SMSED-PP fiber was increased with the ad- dition of SMSED in the fiber, while the breaking tenacity and breaking elongation were decreased. The afterglow intensity of SMSED phosphors was obviously higher
than that of SMSED-PP luminescent fibers, with an initial intensity of 2.6 cd/m2. SMSED-PP fibers containing SMSED of 5 wt.% and 10 wt.%, whose afterglow inten- sities were close, and the overall level was low, with an initial intensity of only approximately 0.3–0.5 cd/m2, revealed better breaking tenacity, breaking elongation and spinnability. The SMSED-PP fiber containing SMSED of 20 wt.% showed better afterglow intensity, with an initial intensity of 1.09 cd/m2, but a poor spinnability. The end breakage rate was increased significantly during the spinning process with a low level of the breaking tenacity and breaking elongation. When the content of SMSED phosphors was 15 wt.%, the SMSED-PP fiber revealed good tensile properties, spinnability and afterglow intensity, with initial afterglow intensity up to more than 0.8 cd/m2, the breaking tenacity of 3.05 cN/dtex and breaking elongation of 15.5%, thus meeting with the requirements of practical product applications.