Journal of chemical health & safety最新文献

We report a case study on the spontaneous detonation of 6-azidotetrazolo[1,5-b]pyridazine, a compound that has been described as being stable despite having an N/C ratio of 2. We share the details of the incident and the lessons learned so that the potential hazards are reported for those who consider its use in the future. The compound was synthesized and handled five times without incident but then detonated upon standing. A one-pot technique to directly convert this hazardous material to the nonenergetic intermediate compound 6-hydroxytetrazolo[1,5-b]pyridazine is also provided.

The ability to control and tune physicochemical properties that underscore chemical behavior in living systems and the environment is at the “heart” of green chemistry. This is especially true for chemical classes designed a priori to be biologically active, such as pesticides, where the chance of unintended adverse outcomes is high. We recently proposed a design-vectoring framework, leveraging validated computational models of ecotoxicity and indirect photodegradation as a useful, quasisystems-based tool for screening existing and designing new agrochemicals. Here, we describe the development of a database that integrates our models, which link structural and substructural features to process metrics, and corresponding predicated data for all agrochemicals with photodegradable cores on the U.S. Environmental Protection Agency’s registry (785 compounds and over 18,000 pairwise interactions with chromophoric dissolved organic matter, CDOM). The database is searchable by structural and nonstructural identifiers (e.g., chemical class, oxidizable core, physicochemical and electronic properties, etc.) to aid in chemical selection, hazard, and alternative assessment. Crucially, it can be easily updated and augmented to aid in interactive data-sharing across industry, government, and academia. The overarching goal of this project is to spur grander efforts in systems-based design of pesticides that would see this platform paired with target-based computational methods and incorporated into the discovery phase of new product development across industry sectors.

The belief that a good law demands preemptive obedience to maintain its stability and reliability seems to run counter to scientific critical thinking, which is to think independently and question assumptions. This study discusses possible decisions by different laboratories with different research purposes in disposing of an alkali metal. Through the analysis, we consider why scientists follow or violate relevant safety rules. Using Joseph Raz’s service conception of authority and legal philosophers’ observations, we have found that to reduce the risk of accidents caused by professional autonomy and rational noncompliance, the academic community should focus on improving and deferring to the preemptive qualified legislative authority, which should exercise its power cautiously to avoid marginalizing public interests.

Action cameras are widely popular in daily life to record images of a panoramic view, fast random shooting, and extreme sports. It is regrettable that there is no academic study on the abusive risk associated with the lithium-ion batteries equipped in sports cameras. In this work, the thermal runaway (TR) phenomena of GoPro Li-ion batteries (LIB) with a stage of charge (SOC) of 0, 25, and 50% were investigated. The battery samples were tested by using an accelerated rate calorimeter (ARC) equipped with a specially customized battery holder. The internal materials of the battery were disassembled for characterization. The results show that the TR power of the GoPro LIB should not be underestimated albeit with low or medium battery capacity. During the TR course, the maximum temperature of the 50% SOC LIB can reach 470 °C, which is close to the maximum temperature limit of ARC. The maximum self-heat rate can exceed more than 1000 °C min^–1. Moreover, the TR risk of the LIB increases with the high value of SOC. It is worth mentioning that the initial decomposition process of the solid electrolyte interface (SEI) was monitored, which resulted in the onset of the TR. In addition, the cathode material was determined to be LiCoO₂, while that of the separator was verified to be polyethylene (PE). Microscopically, it can be found that the internal material was obviously destroyed after thermal runaway. In addition, through the thermal stability characterization and instrumental analysis of the battery’s components, it can be found that the TR is strongly related to the breakdown of the separator.

Flame retardancy is a desirable property of polymer materials, and the molecular design of novel flame-retardant structures considers three main aspects: (i) the chemical structure should have suitable thermal degradation temperature and a high tendency to form char; (ii) the flame-retardant molecule should not compromise the mechanical properties of the polymer matrix; and (iii) the molecule should have low inherent toxicity and generate minimal or no harmful substances to humans and the environment during degradation. Azaheterocycles and their derivatives are an important class of nitrogen-containing flame retardants, which achieve good flame retardancy by diluting the concentration of oxygen and fuel gas on the polymer surface in the gaseous phase and promoting the amount of char residue in the condensed phase. At the same time, azaheterocycle-containing flame retardants possess excellent designability and appropriate thermal degradation temperature of most of their structures, producing gases with low toxicity when subjected to thermal decomposition. Moreover, azaheterocycles and their derivatives have promising potential in the synthesis of novel flame retardants and flame-retardant polymers. This review mainly summarizes the methods of improving the flame retardancy of polymeric materials using azaheterocycle-containing compounds and the applications of azaheterocycle-containing flame retardant molecules. Meanwhile, this review also identifies the main challenges for the future development of azaheterocycle-containing flame retardants.

People have created hybrid materials for centuries by molecularly blending two different materials. Particle brushes are an emerging type of hybrid material in which polymer brushes are grafted from or onto the surfaces of micro/nanoparticles. Silica is the most prevalent choice of core in particle brushes. Normally, hydrofluoric acid (HF) is used to etch these particles prior to chromatographic analysis of the detached polymer, but HF is particularly hazardous to humans and the environment. Herein we report the use of nonvolatile fluoride instead of HF in the sample pretreatment. We found the effectiveness of aqueous ammonium bifluoride (NH₄HF₂) is comparable to HF etching and extended it to particle brushes with other inorganic cores such as barium titanate. This technique is promising for silica template removal in other nanomaterials. Our findings may inspire future efforts in hazard control by substitution in research protocols.