Fabrication of bilayer antioxidant microcapsule and evaluation of its efficiency in stabilization of polypropylene

In recent years, there has been increasing interest on maintaining the efficiency of Polypropylene (PP) fibers by various methods during its application. In this paper, bilayer antioxidant microcapsules were successfully prepared with Irgafos168 as inner core, hindered polyphenol as inner shell, and TEMPO as outer shell via in situ polymerization method combined with water phase separation method. Structure and property of microcapsules were investigated by FT-IR, XPS, SEM, and TGA analysis. Results showed that microcapsules were successfully prepared with bilayer structure. Microcapsules had spherical shape with particle sizes of 1.09 ± 0.35 μm. They also had good thermal stability to ensure stable structure and property during melt-spinning process. These microcapsules were then blended with PP melts to fabricate composite PP fibers via melt-spinning technique. DSC measurement and accelerated aging treatment was performed to investigate the effect of microcapsules on aging resistance of composite PP fibers. Results showed that the addition of bilayer microcapsules significantly increased the onset oxidation temperature and decreased the aging rate of PP fibers, indicating that the addition of bilayer microcapsule effectively improved the aging resistance of PP fibers. Furthermore, the addition of microcapsules contributed to maintain sound surface morphology of PP fibers.