In this study, the surface flame retardancy of polycarbonate (PC) was improved and the impact of flame retardants on the substrate were minimized by pre-mixing Al2O3 particles with dichloromethane, an infiltration promoter, to form a suspension, and then treating PC with the suspension to form an Al2O3 infiltration layer. For this layer, its structure and composition were characterized, its flame retardancy was evaluated, and its flame retardancy mechanism was investigated. The characterization results confirmed that an Al2O3 infiltration layer was successfully prepared on the PC surface under the aid of dichloromethane and that the involvement of dichloromethane induced certain microscopic pores and voids in the PC, with some dichloromethane remaining within the surface infiltration layer. The surface Al2O3 infiltration layer mainly served as a condensed-phase flame retardant. The infiltration layer prepared using a suspension with a dichloromethane-to-Al2O3 mass ratio of 24:1 not only exhibited a good overall performance but also achieved the best improvement in the PC flame retardancy, such as an increase in the vertical burning rating from HB to V-0, as well as the LOI increased from 24 to 31.3, and a 35% reduction in the peak heat release rate compared to those of pure PC.
Ning Yang,Hui Ma,Qiwei Bo,Jiaming Li,Ning Sun,Caili Dai,Guang Zhao
The breakthrough flow channel generated by formation heterogeneity has severely restricted oil recovery improvement, and its identification and control methods have received extensive attention. In this study, we developed a novel fluorescent dispersed particle gel (FDPG) for identifying and regulating breakthrough flow channels based on the dispersed particle gel (DPG). A copolymer of acryloyl fluorescein and acrylamide (PAMAF) was synthesized by free-radical copolymerization for the preparation of the FDPG. The fluorescence properties and identification method of FDPG were systematically investigated. The results showed that the FDPG had stable fluorescence properties, and its concentration showed a linear relationship with fluorescence intensity . The excitation and emission wavelengths of FDPG fluorescence fall within the interval that can avoid the influence of crude oil on its detection. FDPG can accurately reflect the migration of particles in the formation and avoid the chromatographic separation effect. FDPG has excellent injection and migration properties and can effectively control the high permeability layer after ageing. By analysing the output of the FDPG, breakthrough flow channels that exist between formation layers and within well groups can be effectively identified. FDPG provides a promising approach for identifying breakthrough flow channels and monitoring particle profile control agents.
Shichun Li,Haobin Zhang,Shuwen Yu,Jingwei Hou,Shiliang Huang,Yu Liu
Polymeric composite membranes have emerged as the leading technology in industrial gas separation fields for decades, but there are still several unsolved fundamental problems on the interface between layers in composite membranes, which hinders the development of membranes with better performance. The penetrating layer locating between the selective layer and the supporting layer of composite membranes could strongly affect both gas separation performance and durability of membranes, the understanding of the penetrating layer is however limited. The bottleneck in studying penetrating layer is structure characterization, as the penetrating layer is hard to be distinguished from the selective layer and the supporting layer by an electronic microscope. Here, the nanoporous structure of the penetrating layer in the polydimethylsiloxane (PDMS)/polysulfone (PSf) composite membrane was characterized by small angle X-ray scattering (SAXS) that measures variations of nano-pore size distribution of membranes. The penetration degree was quantitatively described as a relative reduction in gyration radius of pores measured by SAXS. In the penetration process, the repeated cycles of penetration and drying of PDMS solution in pores occurred, which filled the small pores and divided the big pore into smaller ones. Moreover, the effects of penetrating layers on the gas transport property of composite membranes were estimated by using restriction factor in which the restriction effect of the supporting layer was also considered, and high correlation between penetration degree and restriction factor was presented.
危险品化学品经营许可证（带存储）