Fang Zhu

Novel double-shell PA-MEL@PU@CFO microcapsules were successfully prepared by further coating the as-prepared PU@CFO microcapsules with the outer shell of phytic acid-melamine salt (PA-MEL). The fire suppression performance was then investigated in a simulated confined space experimental device. Effects of the emulsification conditions on the morphology of microcapsules were investigated in detail. Systematic characterization results demonstrated that the double-shell structure was successfully constructed. PA-MEL@PU@CFO microcapsules fabricated under the optimal emulsification conditions exhibited regular spherical morphology with rough flocculent surface and uniform particle size. The introduction of the outer PA-MEL shell raises the release temperature of core material, thereby improving the low-temperature storage stability of the microcapsules and facilitating their storage and transportation. PA-MEL@PU@CFO microcapsules exhibited favorable storage stability overall, with a relatively high core content of 53.18%. PA-MEL@PU@CFO microcapsules demonstrated excellent flame retardant and fire-extinguishing performance for the fires in confined spaces at the incipient fire stage, reducing the maximum flame temperature by 238.6 °C, shortening the extinguishing time by 53 s, and effectively inhibiting flame re-ignition. PA-MEL@PU@CFO microcapsules achieved efficient fire suppression by a synergistic effect of physical cooling, chemical suppression and phosphorus–nitrogen synergistic flame retardancy. PA-MEL@PU@CFO microcapsules hold great practical application potential in practical application such as anti-flame coatings and lithium-ion batteries.

To investigate the international development status and hot trends in the field of environmental security management in recent years, the published the environmental security management literature from 1997 to 2021, which was retrieved from Web of Science, with VOSviewer as the main and CiteSpace as the auxiliary, through the cooperation network of authors, scientific research institutions, and countries. The keywords were visualized by clustering, time zone analysis, and burst analysis. A total of 7596 articles were retrieved, forming six main clustering labels, including 28,144 authors. The research hotspots are from the fields of personal health, society, agriculture, ecological environment, energy, and sustainable development, as well as the development of internet environmental safety management, such as big data, Bayesian networks, and conceptual frameworks. Through cluster analysis, the cooperation of major research teams and scientific research institutions and the cooperation and development between countries were analyzed. The cooperation between scientific research institutions in various countries is relatively close. The United States currently occupies a dominant and authoritative position in this field. China has cooperated more closely with the United States, Britain, Australia, and India.