Puerarin, an efficient natural stabilizer for both polyethylene and polypropylene

Puerarin, a natural compound, was used as multifunctional protector for polyethylene (PE) and polypropylene (PP). Firstly, puerarin and tetrakis(2,4-di-tert-butylphenol)[1,1-biphenyl]-4,4′-diylbisphosphite (PEPQ) could protect PE and PP against thermos-oxidative degradation: after modification, the oxidation induction time (OIT) of increased ca. 4,160% (PE-P 1200 -P sample) and 130% (PP-P 1200 -P sample); the carbonyl index (CI) obtained through accelerated aging decreased ca. 58% (PE-P 1200 -P sample). Secondly, it is excited to find that puerarin and PEPQ could pretect PE agianst photooxidative degradation: CI value decreased ca. 35% after modification. Thridly, the coorperation of puerarin and PEPQ was also benefit for the processing stability: the change of melt flow rate (MFR) between first and fifth extrusions decreased ca. 83% (PE-P 1200 -P sample) and 99% (PP-P 1200 -P sample). Forthly, puerarin and PEPQ could still protect PE against degradation after five extrusions: the loss of tensile strength and elongation at break decreased ca. 96% and 95% after modification. Finally, the interaction of puerarin with PEPQ was discussed and the role of puerarin in protecting polyolefins was proposed.