Filtern
Erscheinungsjahr
- 2017 (32) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (11)
- Posterpräsentation (10)
- Vortrag (9)
- Forschungsbericht (2)
Sprache
- Englisch (32)
Schlagworte
- Nanoparticles (21)
- SEM/EDX (7)
- Nanomaterial classification (6)
- SEM (6)
- Electrospray deposition (5)
- Nanomaterial (5)
- TiO2 (5)
- Electron microscopy (4)
- TEM (4)
- Fluorine (3)
Eingeladener Vortrag
- nein (9)
The VSSA approach has the important advantage over classifying, imaging and counting techniques that it does not involve dispersion protocols. Further, the BET technique as the basis for VSSA determination it is in widespread use, generates low costs and is specified for many commercial materials. Finally, the same equipment allows for a deeper analysis by full isotherm evaluation.
The present deliverable assesses all NanoDefine powders, supplemented by further real-world materials (in total 26 powders), and quantitatively compares the relationship between the median size (by Electron Microscopy – considered as benchmark for the EC nanomaterial definition) vs. the size derived from VSSA. The VSSA method mitigates the challenges of EM to assess the thickness of platelets, but worked as well on fibbers and particles of irregular shapes. A screening strategy is proposed. If applied to the further data from real-world materials as validation set, this screening does achieve a correct classification, leaving only borderline materials for tier 2 assessment.
In this lecture the VSSA concept is explained, and VSSA as measured by BET. Results of the NanoDefine evaluation based on selected examples on real-world materials are presented. Recommendations for consideration of the VSSA concept for the implementation of the EC definition of nanomaterial for powder materials are given.
In October 2011 the European Commission (EC) published a "Recommendation on the definition of na-nomaterial" (2011/696/EU), to promote consistency in the interpretation of the term "nanomaterial" for legislative and policy purposes in the EU. The EC NM Definition includes a commitment to its review in the light of experience and of scientific and technological developments. This review is ongoing in 2017 and as a contribution to the review the Joint Research Centre of the European Commission (JRC) has already developed a series of three scientific-technical reports with the title: “Towards a review of the EC Recommendation for a definition of the term nanomaterial” which provides to the EC policy services sci-ence-based options on how the definition could be revised or supported with additional guidance.
The overarching nature and wide scope of the EC NM Definition, as it does not exclude a priori any particulate material regardless the state, form and size, creates many analytical challenges in its imple-mentation for all stakeholders, including enterprises and regulators.
The NanoDefine project has as core objective to support the implementation of the EC NM Definition. In an earlier report1 key aspects of the EC NM Definition were addressed, with the goal to improve the implementability of the EC NM Definition. Based on further developments and results obtained in NanoDefine project that first report was updated and is presented here. The key aspects are discussed based on the results of four years of research performed within the framework of the project. As a result this report assesses how well the requirements of the EC NM Definition can be fulfilled with currently available analytical possibilities. It presents recommendations and options on a revision of the EC NM Definition to improve the implementability of the definition based on currently available analytical possi-bilities, according to the state of the art in 2017. Of the technical issues considered in this report, the following seem to deserve the most attention in terms of clarification of the definition and/or provision of additional implementation guidance: 'external dimension', ‘number based particle size distribution‘, ‘polydispersity‘ and ‘upper size limit‘, the term ‘particle’, the ‘means to prove that a material is not a nanomaterial‘ and ‘the role of the volume specific sur-face area (VSSA)‘, and "particulate materials'.
The presentation goes into the characterization of TiO2 engineered nanoparticles within EU/FP7 SETNanoMetro Project and the nanomaterial classification according to the EC definition tested within EU/FP7 NanoDefine Project. Further, ISO/TC 229/JWG 2 activities related on ISO standards in development and inter-laboratory comparisons on measurement of nanoparticle size and shape distribution by SEM and TEM are discussed.
At the Final Outreach Event of the European FP7 NanoDefine project the results achieved during 4 years of intensive research and development work (2013-2017) with relevant stakeholders and wider community, and their practical implications and impact are presented and discussed. The newly developed particle-size related measurement tools and their practical suitability and applicability to classify materials, formulations and products according to the EC recommendation on the definition of a nanomaterial (2011/696/EU) are demonstrated.
The capability of currently available particle sizing techniques for reliable classification of materials that potentially fall under the EU Definition of a nanomaterial is discussed. A systematic quantitative evaluation of the sizing techniques is presented together with representative case studies of analysis of industrially relevant materials.
Recommendations on the most appropriate and efficient use of techniques for different types of material are given.
The large European nanometrology Project NanoDefine is presented briefly with respect to the challenges of measurement of particle size distribution for complex nanoparticulate materials.
The methods chosen for a tiered approach for the classification of a nanomaterial are discussed with regard to their peformance. Representative resuls on real life, complex shaped nanoparticulate materials are shown.
The recently initiated VAMAS inter-laboratory comparisons to determine the reproducibility necessary for international standardisation have been also presented.
Evaluation of particle sizing techniques for implementation of the EC Definition of a nanomaterial
(2017)
Many techniques are available for measuring particle size distribution. For ideal materials (spherical particles, well dispersed) it is possible to evaluate the Performance of these methods. The performance of the analytical instrumentation for the purpose of classifying materials according to EC Definition is unknown. In this work the performance of commercially available particle sizing techniques on representative NanoDefine set of real-world testing materials (RTM) and quality control materials (QCM) for the implementation of the Definition is evaluated.
Reliable nanomaterial classification of powders using the volume-specific surface area method
(2017)
The volume-specific surface area (VSSA) of a particulate material is one of two apparently very different metrics recommended by the European Commission for a definition of "nanomaterial" for regulatory purposes: specifically, the VSSA metric may classify nanomaterials and non-nanomaterials differently than the median size in number metrics, depending on the chemical composition, size, polydispersity, shape, porosity, and aggregation of the particles in the powder.
Here we evaluate the extent of agreement between classification by electron microscopy (EM) and classification by VSSA on a large set of diverse particulate substances that represent all the anticipated challenges except mixtures of different substances. EM and VSSA are determined in multiple labs to assess also the level of reproducibility. Based on the results obtained on highly characterized benchmark materials from the
NanoDefine EU FP7 project, we derive a tiered screening strategy for the purpose of implementing the definition of nanomaterials. We finally apply the Screening strategy to further industrial materials, which were classified correctly and left only borderline cases for EM.
On platelet-shaped nanomaterials, VSSA is essential to prevent false-negative classification by EM. On porous materials, approaches involving extended Adsorption isotherms prevent false positive classification by VSSA. We find no false negatives by VSSA, neither in Tier 1 nor in Tier 2, despite real-world industrial polydispersity and diverse composition, shape, and coatings. The VSSA screening strategy is recommended for inclusion in a technical guidance for the implementation of the definition.
Volume specific surface area (VSSA) by BET: concept and demonstration on industrial materials
(2017)
Volume specific surface area (VSSA) as measured by BET constituites a simple and reliable solution to (most) powders. Porous, coated, polydisperse/multimodal materials are to be treated with care, i.e. doubled by analysis with electron microscopy or more advanced BET analysis (e.g. t-plot)for each material in part.