Magnesium hydroxide, as a green inorganic flame-retardancy additive, has been widely used in polymer flame retardancy. However, magnesium hydroxide is difficult to disperse with epoxy resin (EP), and its flame-retardancy performance is poor, so it is difficult to use in flame-retardant epoxy resin. In this study, an efficient magnesium hydroxide-based flame retardant (MH@PPAC) was prepared by surface modification of 2-(diphenyl phosphine) benzoic acid (PPAC) using a simple method. The effect of MH@PPAC on the flame-retardancy properties for epoxy resins was investigated, and the flame-retardancy mechanism was studied. The results show that 5 wt% MH@PPAC can increase the limiting oxygen index for EP from 24.1% to 38.9%, achieving a V-0 rating. At the same time, compared to EP, the peak heat release rate, peak smoke production rate, total smoke production rate, and peak CO generation rate for EP/5 wt% MH@PPAC composite material decreased by 53%, 45%, 51.85%, and 53.13% respectively. The cooperative effect for PPAC and MH promotes the formation of a continuous and dense char layer during the combustion process for the EP-blend material, significantly reducing the exchange for heat and combustible gases, and effectively hindering the combustion process. Additionally, the surface modification of PPAC enhances the dispersion of MH in the EP matrix, endowing EP with superior mechanical properties that meet practical application requirements, thereby expanding the application scope for flame-retardant EP-blend materials.

In this paper, S95 grade ultrafine mineral admixture was prepared by water quenched manganese slag and fly ash 1:1 compound mechanical ball milling to a specific surface area of 714 m²/kg. Its activity index was 86.8% at 7d and 96.3% at 28d. The S95 ultrafine mineral admixture prepared by ball milling has the characteristics of small particle size, high specific surface and high activity. Mixing with powders of different particle sizes, such as cement and silica fume, is helpful to improve particle gradation, reduce its pore structure and increase its compacting property for UHPC whose raw materials are fine aggregate. Ultra-high performance concrete (UHPC) was prepared by using the obtained ultrafine mineral admixture based on orthogonal test. The effects of different factors on the workability, mechanical properties, hydration heat and microstructure of UHPC were studied. The results show that when the silica fume content is 10%, the mineral admixture content is 10%, the binder-sand ratio is 1.1, and the water-binder ratio is 0.17, the fluidity of UHPC slurry can reach 261 mm, the compressive strength of 7d and 28d age can reach 128 MPa and 154.6 MPa, respectively. The hydration heat release of cementitious materials in 3d was 139.8 J/g. In terms of solid waste resource utilization, S95 grade ultrafine mineral admixture prepared by water-quench manganese slag and fly ash can replace 10% silica fume for the preparation of UHPC. It can not only solve the utilization problem of high added value of water quench manganese slag, but also reduce the preparation cost of UHPC to a certain extent.

The oxidative cracking of diformyltricyclodecanes (DFTD) to C6–C8 alkenes and alkenes were systematically studied in this work. A series of experiments was performed over a broad range of conditions (temperature: 40–60 °C; oxygen pressure: 0–1.0 Mpa; reaction time: 5–90 min, solvent selection) for exploring the reaction route and mechanism. Results show that the higher temperature and oxygen pressure, as well as tetrahydrofuran (THF) as solvent are of benefit to the generation of cracking products. In addition, the kinetics of this reaction was explored by the dynamic fitting. The obtained kinetics parameters demonstrate that the transformation of intermediate to cracking products possesses higher activation energy than to dicarboxyltricyclodecaneacids (DCTDA), showing that higher temperature is conducive to the generation of DFTD cracking products. This work firstly demonstrated that DFTD could be formed into C6-C8 alkenes containing the same as gasoline compound by the oxidative cracking, suggesting that the by-product of petroleum and coal could be transferred into fuels; this expanded the application of DCPD and will have significant and positive influence on the petroleum and coal chemical industry.