Forsythia suspensa extract obtained from traditional Chinese herbal medicine as an efficient natural antioxidant for polyethylene.

Forsythia suspensa extract (FSE) obtained from traditional Chinese herbal medicine was employed as the stabilizer for polyethylene (PE). The effects of FSE on the thermos-oxidative stability, processing stability and mechanical properties of PE have been discussed through comparison of the performance of pure PE and modified PE samples on oxidation induction time (OIT), melt flow rate (MFR) and tensile tests. With the addition of FSE, the thermal oxidation stability of samples noticeably improved even after multiple extrusions: An OIT value of ca. 65.0 and 45.5 min could be achieved with PE-FSE0.8-626 sample after the first and fifth extrusions, which is extremely higher than pure PE. The improved antioxidant performance could be ascribed to the attractive free radical scavenging efficiency of FSE, confirmed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical–scavenging experiment. MFR results showed that FSE could effectively enhance the processing stability of PE matrix, the change of MFR after five extrusions was only 0.22 g/10 min for PE-FSE0.8-626 sample. Moreover, the tensile strength and elongation at break increased after the addition of FSE, which also maintained through the five extrusions. In addition, the cooperation of FSE and Ultranox 626 on the stability of PE was also explored. All results reveal that forsythia suspensa extract was good and multifunctional stabilizer for PE. This study opens up novel opportunities in utilizing traditional Chinese herbal medicine as natural antioxidants for the thermal oxidation stability of polyolefin, which is benefit for the development of sustainable and environmental friendly polymers. [ABSTRACT FROM AUTHOR]