Anna Zheng,Yongkang Huang,Yang You,Jian Hu,Dafu Wei,Xiang Xu,Yong Guan
The heat resistance enhancement of fluorosilicone rubber (FSR) can make it more suitable for cutting-edge applications and extreme conditions. This paper focused on the antioxidant properties of boron particles for FSR and the corresponding mechanism. The thermal stability of FSR and FSR/boron composites was characterized by thermal gravimetric analysis (TGA), isothermal degradation and thermal-oxidative ageing. The results showed that boron significantly improved the thermal stability of FSR. In particular, the FSR/boron (100/10) composite retained 95% of its weight after isothermal degradation at 350 °C for 12 h, while the FSR lost 55% of its weight within the initial 1 h. The antioxidant mechanism of boron was further investigated by chemiluminescence (CL), electron paramagnetic resonance (EPR) and vulcanization curves. It was shown that boron has powerful radical scavenging activity (RSA) and inhibited the oxidation scission of the side groups. Moreover, boron revealed no RSA towards the tert-butoxy radical, ensuring the good vulcanization of the FSR/boron composites.
Maillard reaction products (MRPs) were prepared by reacting both Yak and Holstein casein with different ratios of glucose to casein from 0:1 to 2.5:1. The results showed that the content of intermediate products and browning intensity of the Yak casein-glucose system increased with increasing concentrations of glucose, but were lower than for the Holstein system at the same ratio. With glycosylation, the reducing power and the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of both Yak and Holstein caseins were enhanced. With increased glucose content, the reducing power of Yak MRPs increased at the same concentration. The metal chelating activity of Holstein MRPs decreased or was eliminated in the ratio range of 0.5:1 to 2.0:1 g glucose g −1 casein, while that of Yak MRPs were reduced in general. Improvement of the inhibitory activity for Yak casein was lower than that of Holstein casein after glycosylation by glucose.
危险品化学品经营许可证（带存储）