Effect of nano-TiO2 immobilized antioxidant on ageing resistance behavior of thermoplastic vulcanizate exposed to UV/O3

Effect of UV Light on the Barrier Performance of Aluminum Powder/Epoxy Coating

Spherical aluminum powder was added to an epoxy composite coating in order to improve its protection performance for metal materials. The strength of the coating before and after UV (Ultraviolet Light) aging, its yellowing value, and its barrier properties were tested to explore the influence of UV light on the barrier performance of aluminum powder/epoxy coating. The results show that the addition of the aluminum powder enhanced the strength of the epoxy coating and reflected environmental UV light. This improved the resistance of the coating to UV aging and prolonged its service life. The composite prepared with 6 wt.% aluminum power exhibited the highest strength values before and after aging: 64.5 MPa and 58.5 MPa, respectively. After aging, the strength loss rate of this epoxy coating was 9.3%, and its yellowing value was +1.43.

Study on Thermal-Oxidative Aging Properties of Ethylene-Propylene-Diene Monomer Composites Filled with Silica and Carbon Nanotubes

In this work, a small amount of carbon nanotubes (CNTs) was used to partially replace the silica in ethylene-propylene-diene monomer (EPDM) to prepare EPDM composites via mechanical blending. The mechanical properties, thermal-oxidative aging properties and thermal stability of the composites were systematically investigated. The results showed that with the increase of CNTs content, the Shore A hardness and stress at 100% strain of the composites increased, while the elongation at break decreased. With the aging time increasing, the aging coefficient and elongation at break of composites decreased while hardness increased due to the raise of crosslinking density. In addition, evidences were found to demonstrate the improved aging resistance by adding CNTs in the EPDM composites, including the less change in Shore A hardness, the smaller change ratio of elongation at break and the lower aging coefficient. When the content of CNTs reached 10 phr, the aging coefficient of the EPDM composite aged for 168 h was nearly twice that of the composite without CNTs, and the thermal stability of the EPDM composite with CNTs was improved as demonstrated by thermal analysis.

Meta-cresol degradation by persulfate through UV/O3 synergistic activation: Contribution of free radicals and degradation pathway

The kinetic and pathway of meta-cresol (m-cresol) degradation were studied by persulfate oxidation through UV/ozone activation (UV/O₃-Na₂S₂O₈) to improve m-cresol removal to eliminate ecological risks. Experimental results showed that the degradation effect of m-cresol with an initial concentration of 50 mg/L was 99.8% in 30 min under the optimization conditions. The reaction kinetic model in the UV/O₃-Na₂S₂O₈ system shows that the initial pH value, the respective ozone, and the persulfate dosage were positively correlated with the degradation rate constant value (k). The apparent degradation rate of m-cresol in the UV/O₃-Na₂S₂O₈ system was 0.2216 min^-1, and the synergy factor (f) was larger than 1, thereby demonstrating a synergistic effect of UV, ozone, and persulfate. The dominant free radicals in the system were sulfate radical (SO- 4·) and hydroxyl radical (·OH), and the contribution ratio of SO- 4· to m-cresol degradation was higher than ·OH. The degradation process of m-cresol by UV/O₃ - Na₂S₂O₈ was mainly through the electrophilic addition reaction to substitute the ortho- and para-positions of the hydroxyl group on the benzene ring, followed by the ring-opening reaction and mineralization of the aliphatic compound to achieve the complete degradation of m-cresol.