Effect of Compatibilizer on the Persistent Luminescence of Polypropylene/Strontium Aluminate Composites.

There is a demand for long afterglow composites due to their potential applications in nighttime signal boards, sensors, and biomedical areas. In this study, Polypropylene (PP)/strontium aluminate-based composites [SrAl 2 O 4 :Eu 2+ /Dy 3+ (SAO 1 ) and Sr 4 Al 14 O 25 : Eu +2 , Dy +3 (SAO 2 )] with maleic anhydride grafted PP compatibilizer (PRIEX) were prepared, and their auto-glowing properties were examined. After UV excitation at 320 nm, the PP/5PRIEX/SAO 1 composites showed green emission at 520 nm, and blue emission was observed for PP/5PRIEX/SAO 2 around 495 nm. The intensity of phosphorescence emission and phosphorescence decay was found to be proportional to the filler content (SAO 1 and SAO 2 ). The FTIR analysis excluded the copolymerization reaction between the SAO 1 and SAO 2 fillers and the PP matrix during the high-temperature melt mixing process. The SAO 1 and SAO 2 fillers decreased the overall crystallinity of the composites without affecting the T m and T c (melting and crystallization temperature) values. The thermal stability of the composites was slightly improved with the SAO 1 and SAO 2 fillers, as seen from the TGA curve. Due to the plasticizing effect of the compatibilizer and the agglomeration of the SAO 1 and SAO 2 fillers, the tensile modulus, tensile strength, and storage modulus of the composites was found to be decreased with an increase in the SAO 1 and SAO 2 content. The decreasing effect was more pronounced, especially with the bulk-sized SAO 2 filler.