To promote the anti-aging performance of thermoplastic vulcanizates (TPVs) versus ultraviolet (UV)/O3 exposure, a nano-TiO2-loaded antioxidant (TiO2-KH570-MB) was prepared by a thiol–ene reaction between 2-mercaptobenzimidazole (MB) and modified nano-TiO2 (TiO2-KH570). Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis demonstrated the chemical linkage between MB and modified nano-TiO2, and the loading amount of MB was approximately 5.19 wt %. The contact angle test showed that the surface hydrophobicity of TiO2-KH570-MB was significantly increased due to the immobilization of MB. Scanning electron microscopy revealed that TiO2-KH570-MB was uniformly distributed in the TPV matrix. The anti-aging property of TPV compounds was tested in the device with high-intensity ultraviolet radiation and high-concentration ozone. The effects of UV/O3 comprehensive aging on the TPV compounds were evaluated by means of the variations of surface morphology, tensile test, hardness, gel content, and carbonyl index with aging time. On the basis of the aging behavior, we concluded that TPV/TiO2-KH570-MB exhibited excellent stability against UV/O3 aging, due to the homogeneous dispersion, low level of migration, and low volatility of TiO2-KH570-MB.
Nano-TiO 2 immobilized antioxidant (TiO 2 -KH550-AG) was prepared to improve the ageing resistance of thermoplastic vulcanizate (TPV) exposed to UV/O 3 . TiO 2 nanoparticles were firstly modified with 3-aminopropyltriethoxysilane (KH550) and then reacted with the antioxidant , 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid (AG), through the acyl chloride reaction followed by the amidation. FT-IR, XPS and TGA measurements confirmed that the antioxidant (AG) was chemically immobilized onto the nano-TiO 2 surfaces. TPV/TiO 2 -KH550-AG nanocomposites were prepared by melt mixing. SEM observation showed that TiO 2 -KH550-AG was homogeneously dispersed into the matrix of TPV. The UV/O 3 ageing test of the samples was carried out in the environment with constant UV intensity of 1.40 mW/cm 2 and ozone concentration of 100 ± 4 mg/m 3 . The ageing resistance behavior of the TPV/TiO 2 -KH550-AG nanocomposites was evaluated by the changes of surface morphology , mechanical properties and carbonyl index during the UV/O 3 ageing test. It was observed that the TPV/TiO 2 -KH550-AG exhibited high stability during the process of UV/O 3 ageing. The results revealed that the anti-ageing efficiency of TiO 2 -KH550-AG was superior to the mixture of the corresponding AG and modified TiO 2 , owing to the better dispersion and migration resistance of TiO 2 -KH550-AG.
Juan Zhou,Peng Deng,Hongxing Gui,Junxiao Xu,Jianhe Liao,Aiwu Ding
For the actual storage and serving, a phenomenon of hardening and cracking always occurs in the natural rubber (NR), which sharply reduces the mechanical performance and hinders the further application of NR. Recently, some type of constant-viscosity agent has played a key role to be used for the treatment of NR, especially for the effect of ozone aging resistance. In this study, 2-mercaptobenzothiazole (MBT) was introduced into NR, and the constant viscosity and ozone aging resistance of NR with different contents of MBT were investigated using an accelerated storage experiment and an ozone aging experiment, respectively. The results indicated that the addition of MBT could improve the constant viscosity of NR in a certain degree. With the MBT content of 0.15%, NR/MBT-0.15 obtained a best ozone aging resistance and maintained the original high tensile strength. Therefore, it provided a promising route to design and prepare NR with high-quality ozone aging resistance.
As a renewable and widely applied bio-based material, the relatively weak resistance of natural rubber (NR) resulting from the inherent unsaturated structure to the harsh environments limits their further applications in some special areas. Thus, the fluorinated natural rubber (FNR) latex was prepared with fluorinated acrylate as the monomer in aqueous emulsion system at ambient temperature. The fluorinating reaction, the structure and morphology of NR latex were examined. It was demonstrated that as the intrinsic surface layer of NR latex particles, the non-rubber component hindered the penetrating of fluorinated monomer or initiator radicals into the inner NR Latex particles and reduce the grafting reactivity. The fluorination renders the resultant FNR latex film strong hydrophobicity and superior environmental resistance to UV, ozone, and heat. The defective time of the FNR latex film improved 65 times as long as the net NR latex film via ozone aging. The thermal decomposition temperature increased by 37.0°C compared with net NR latex film. This work provides a facile way for preparation of FNR with excellent stability under extreme environments such as high ozone concentration, high UV intensity and high temperature.
危险品化学品经营许可证（带存储）