Influence of scutellaria baicalensis extract on the thermo-oxidative and composting stability of poly(butylene adipate-co-terephthalate)

Scutellaria baicalensis extract (SBE), as a natural phenolic antioxidant, was added to poly(butylene adipate-co-terephthalate) (PBAT) matrix. With the addition of SBE, both the short-term and long-term antioxidant activity of PBAT samples noticeably improved. The results showed that the oxidation onset temperature (OOT) value of the modified sample (PBAT-SBE2.5 sample) is increased by 62 degrees C versus neat PBAT. Compared with neat PBAT with decreased OOT value after 240 days of storage, the OOT values of modified samples showed no significant change after long-term storage. The excellent antioxidant activity is attributed to the high total phenolic content in SBE, which provides significant free radical scavenging efficiency. Additionally, the introduction of SBE could effectively enhance the processing performance of the PBAT matrix, the melt flow rate of PBAT-SBE2.5 increased by ca. 42.6%. Compared with neat PBAT, the addition of SBE has no obvious effect on the mechanical properties of the matrix, the tensile strength remains unchanged and the elongation at break of PBAT-SBE2.5 retains 74%. Composting degradation experiment indicated that the SBE promoted the degradation of PBAT. Moreover, SBE could reduce the surface hydrophilic tendency of the film materials. All results reveal that SBE was a good natural multifunctional stabilizer for PBAT.