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Evaluation of electron microscopy techniques for the purpose of classification of nanomaterials
(2016)
One current and much-debated topic in the characterization of nanomaterials (NM) is the implementation of the recently introduced recommendation on a definition of a nanomaterial by the European Commission. According to this definition, a material is a NM when for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm-100 nm. The European NanoDefine Project was set up to develop and validate a robust, readily implementable and cost-effective measurement approach to obtain a quantitative particle size distribution and to distinguish between NMs and non-NMs according to the definition.
All currently available sizing techniques able to address nanoparticles were systematically evaluated. It was demonstrated that particle sizing techniques like: analytical centrifugation, particle tracking analysis, single-particle inductively coupled plasma mass-spectrometry, differential electrical mobility analysis, dynamic light scattering, small angle X-ray scattering, ultrasonic attenuation spectrometry, but also gas adsorption analysis based on the BET-method can be applied for a screening classification. However, the quality of the results depends on the individual material to be classified. For well-dispersed, nearly spherical (nano)particles most of the sizing techniques can be applied in a quick and reliable way. In contrast, the classification of most real-world materials is a challenging task, mainly due to non-spherical particle shape, large polydispersity or strong agglomeration/aggregation of the particles. In the present study it was shown that these issues can be resolved in most cases by electron microscopy as a confirmatory classification technique.
Electron microscopy techniques such as TEM, STEM, SEM or TSEM (transmission in SEM) are capable of assessing the size of individual nanoparticles accurately. Nevertheless the challenging aspect is sample preparation from powder or liquid form on the substrate, so that a homogeneous distribution of well-separated (deagglomerated) particles is attained. The systematic study in this work shows examples where the extraction of the critical, smallest particle dimension - as the decisive particle parameter for the classification as a NM - is possible by analysing the sample after its simple, dry preparation. The consequences of additional typical issues like loss of information due to screening of smaller particles by larger ones or the (in)ability to access the constituent particles in aggregates are discussed.
By means of practical examples the inherent statistical evaluation of the particle size is highlighted together with all its pitfalls such as setting of a suitable threshold for delimitation of the particle .
Polymerizing Substances
(2017)
Polymerizing substances are classified in different classes of the UN Recommendations on the Transport of Dangerous Goods. Based on incidents a new division 4.1 for polymerizing substances, which are not meet the criteria of the Classes 1-8, was implemented in the regulations. In the lecture, the criteria and the determination of the SAPT (self-accelerating polymerization temperature are discussed.
Since 1999 there has been a continuous development of non-destructive head check inspection. Especially in case of modern rail inspection systems, high demands on a fast, detailed detection and classification of defects called for improved testing methods. Due to the large amount of different rail types and profiles, the adaptation and optimization of algorithms is still in progress. Additional data analysis is under devel-opment for combined eddy current and ultrasonic inspection methods. This presentation gives an over-view of further enhancement and linking of testing systems as well as data processing. Main foci of the development are an improved sensitivity and an increased reliability of the testing results. Also, additional information can be obtained like determination of local hardness and roughness of the rail as well as an enhanced resolution for locating of defects which will be part of the presented work.
The safety characteristics of flammable gases and liquids are required when identifying potentially explosive mixtures and taking appropriate actions concerning explosion protection. Examples are given in this review of the safe handling and evaluation of hazards during the processing, storage, transport, and disposal of flammable liquids and gases. The CHEMSAFE database is presented as a reliable source of safety characteristic data, and ist new open-access version is introduced. CHEMSAFE currently contains assessed properties for about 3000 flammable liquids, gases and mixtures. The lack of a broad experimental foundation in the extensive field of non-atmospheric conditions shows the need for further investigation and standardization. This review summarizes experimental evidence and estimation methods for safety characteristic data under non-atmospheric conditions pointing out current limitations. Suggestions for pre-normative research on safety data under nonatmospheric conditions are given.
This is a short review on ongoing work and interests in Division 2.6 of BAM with a focus on transport regulations and related testing. The behaviour of primer caps in different packaging configurations is addressed and the new apparatus for the "Minimum Burning Pressure" test is presented. Further topics regarding classification are touched with the aim to attract comments and stimulate cooperation internationally.
Differential Scanning Calorimetry (DSC) may be used to avoid testing for explosive and self-reactive properties according to the legal regulations of chemicals substances and dangerous goods.
Demonstrated measured exothermic decomposition energy value significantly affected by numerous factors - choice of sample vessel, sample mass, baseline shape, peak shape, heating rate.
Ammonia Safety
(2023)
Ammonia is an energy source that has been produced and used on a large scale for many decades, primarily as a fertilizer or feedstock in nitrogen chemistry. The CAMPFIRE alliance, founded as part of the "WIR!- Wandel durch Innovation in der Region" funding program of the German Federal Ministry of Education and Research (BMBF), aims to research and develop new energy conversion and storage technologies for the future energy system based on green ammonia. The safe handling of ammonia is an important issue along the entire value chain. Therefore, the alliance has organized a webinar to discuss the topic of ammonia safety and in particular its flammability. BAM's contribution presented the topic of flammability in detail, placed the classification of ammonia in an international, European and national context and presented the basic principles of explosion protection that result from this and must be observed during use and application.