Standards relevant to materials particle characterization

Transcription

1 Faculty of Mechanical Engineering Institute of Process Engineering and Environmental Technology Research Group Mechanical Process Engineering Standards relevant to materials particle characterization Michael Stintz Institute of Process Engineering and Environmental Technology TU Dresden, Germany ISO/TC 24/SC4 Seminar on Standards and standardization as a tool for the dissemination and implementation of research results 14 December Brussels

2 Content Physical and Chemical Characterization ISO/TC 24/SC 4 Particle Characterization Composite materials in paint industry ISO standardization for powder testing Standardization needs Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 2

3 Physical and Chemical Characterization ISO/TC 229 Task Group on Measurement and Characterization for EHS issues relevant to nanomaterials Lead: A. Hight-Walker, NIST, USA Members: from JWG2 and WG3 Task: review (an existing) table from the viewpoint of Measurands Measurement techniques Existing standards, and the need for pre-normative research make recommendations to JWG2 and WG3 for next steps. Background: Guidance on Physico-Chemical Characterization of Engineered Nanoscale Materials for Toxicologic Assessment (ISO/TR13014) to assess materials before they go into a toxicity test. (OECD - WPMN: ref. table) Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 3

4 Newly suggested terms and groupings Constitution: What is it made of? OECD - WPMN: ref. table Agglomeration State/ Aggregation Composition Particle Size/Size Distribution Shape Solubility /Dispersibility* Surface Area Surface Chemistry Composition Surface Chemistry Appearance: What does it look like? Particle Size / Size Distribution Agglomeration State / Aggregation Shape Surface Area Surface Charge Density* Beyond the above, what influences interactions? Surface Charge Solubility Dispersibility Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 4

5 Appearance: What does it look like? Terms Descriptors Measurands Particle Size/Size Distribution Shape The physical dimensions of a particle determined by specified measurement conditions. A sample of particles of differing sizes is described by a size distribution. Geometric form of the external boundary of the particle. 1. Equivalent diameter (equivalent to spherical); unit: [metre] 2. Length of one or several specific aspects of the particle geometry; unit: [metre]; 3. Distribution of values for the measurands above; type of quantity of distribution: number (0), length (1), area (2) or volume (3) distribution; (numbers indicate dimensions) Size-independent Macro, Micro, Meso shape descriptors (examples are ratios of extensions in different directions; unit [metre/metre] such as aspect ratios, or Fractal dimension); many macro-meso-micro descriptors of shape are available (see ISO ). Distribution of values of the size-independent shape descriptors ISO/TC 229 Task Group on Measurement and Characterization for EHS issues relevant to nanomaterials Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 5

6 Appearance: What does it look like? Terms Descriptors Measurands Aggregation/ Agglomeration State Part 1 of 2 - The agglomeration state is a description of the agglomerate at a given moment in time; changes of the agglomeration state are indicative of the dynamic equilibrium which depends on time and the agglomerate environment, which can change the number of primary particles that adhere. -Definitions for agglomerate (loosely bound) and aggregate (strongly bonded): see CEN ISO/TS 27687: Agglom / Aggreg size distribution; refer to particle size measurands; unit [metre] 2. Degree of agglom / aggreg: number of agglom/aggreg particles in comparison to the total number of primary particles; unit [mole / mole] 3. Number of primary particles in the agglomerate or aggregate; Distribution of number of primary particles per agglomerate or aggregate 4. Fractal dimension: averaged aggregate structure, exponent of the power-lawrelationship between aggregation number and aggregate size ISO/TC 229 Task Group on Measurement and Characterization for EHS issues relevant to nanomaterials Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 6

7 Appearance: What does it look like? Terms Descriptors Measurands Aggregation/ Agglomeration State Part 2 of 2 Agglomerate strength describes the stability of the agglomerate with respect to added energy or to changes in the agglomerate s environment. 1. Agglomerate strength 2. Energy necessary to break apart the agglomerate in a specified environment; unit [Joule/kg] 3. Change of environmental conditions required to deagglomerate the agglomerate; ph, temperature Surface Area area of the exposed surface of a single particle, or more general the area of the exposed surface of a certain amount of a material Specific surface area = surface area of a material divided by its mass. SI unit: (metre) 2 /kilogram ISO/TC 229 Task Group on Measurement and Characterization for EHS issues relevant to nanomaterials Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 7

8 Content Physical and Chemical Characterization ISO/TC 24/SC 4 Particle Characterization Composite materials in paint industry ISO standardization for powder testing Standardization needs Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 8

9 Performance of Sizing techniques ISO/TC 24/SC 4 Particle Characterization Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 9

10 ISO/TC 24/SC 4 Particle Characterization WG 1 "Representation of analysis data" WG 2 "Sedimentation, Classification" WG 3 "Pore Size distribution, porosity" WG 5 "Electrical sensing zone methods" WG 6 "Laser diffraction methods" WG 7 "Dynamic light scattering" WG 8 "Image Analysis methods" WG 9 "Single Particle light interaction methods" WG 10 "Small angle X-ray scattering" WG 11 "Sample preparation" WG 12 "Differential electrical mobility analysis for aerosol particles" WG 14 "Acoustic methods" WG 15 "Focused scanning beam techniques" WG 16 Characterisation of particle dispersion in liquids WG 17 "Methods for zeta potential determination" Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 10

11 ISO/TC 24/SC 4 Particle Characterization The sub-committee SC4 Sizing by methods other than sieving of ISO/TC 24 Sieves, sieving and other sizing methods is responsible for developing international standards for particle size analysis. 16 nations are entitled to vote (P-members) and 15 nations are observing members (O-members). Members in Liaison are ISO/TC47 Chemistry, ISO/TC119 Powder metallurgy, ISO/TC206 Fine ceramics, ISO/TC229 Nanotechnologies Standards have been published, 12 Standards are under development. Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 11

12 ISO/TC 24/SC 4 Particle Characterization ISO 9276 Representation of Results of Particle Size analysis : Part 1: Graphical representation, Part 2 : Calculation of average particle sizes and moments from particle size distributions, Part 3: Adjustment of an experimental curve to a reference model, Part 4: Characterization of a classification process, Part 5: Methods of calculation relating to particle size analysis using log. normal probability distribution, Part 6: The descriptive and quantitative representation of particle shape and morphology, ISO/DIS 26824: Particle characterization of particulate systems -- Vocabulary. (Includes 220 definitions, harmonized in relation to ISO-CDB, partially to ISO/TC 229, TC 209 Cleanrooms, TC 146, Air Quality, SC 2, Workplace atmospheres). Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 12

13 ISO :2008 Shape Scope - the relevance of any measure or method of shape representation to technological applications has to be the deciding factor for its selection and not the complete reconstruction of the geometric particle shape. Therefore, this standard is restricted to characterization methods which can be correlated to physical properties in industrial applications. Example descriptors from ISO : Macroshape descriptors: convex hull maximum inscribed circle perimeter box, depending on orientation! Mesoshape descriptors: convexity = convex hull / perimeter circularity = π area equival.diam. / perimeter Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 13

14 Content Physical and Chemical Characterization ISO/TC 24/SC 4 Particle Characterization Composite materials in paint industry ISO standardization for powder testing Standardization needs Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 14

15 Risk Assessment for coating applications Objective: Particle release from nanoparticle containing coatings Strategy: Simulation of typical handling by professional sanding Challenges: Reproducibility of particle generation (and particle dispersion from wear powder into air) Normalization (material amount, air volume, particle size range) Sensitivity of nanoparticle concentration measurement, time stability, nanoparticle background Establishment of treatment method, pre normative research for standardization of measuring methods Researcher: TUD Process Engineering (Particle Characterization Lab) Sponsor: German Paint Industry Association (VdL) Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 15

16 Materials (SEM- and TEM) Architectural coating 20 nm zinc oxide and pigment particles SEM after Cryo-Preparation TEM Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 16

17 Particle Characterization Method Fast Mobility Particle Sizer (FMPS) Number concentrations of the size distribution, based on electrical current measurement Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 17

18 Particle Characterization Method Condensation Particle Counter (CPC) optical detector condensation chamber total concentration 7 nm - > 10 µm 0, p/cm³ 0,3 l/min Mass of a 20 nm ZnO-sphere: 2,35*10-17 g NO GRAVIMETRIC measurement applicable! Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 18

19 Test Setup Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 19

20 Test Setup Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 20

21 Test Setup Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 21

22 Material after sanding process up: furniture coating on metal (two-pack polyurethane) bottom: architectural coating on fibre cement Area [cm²] 13, contact force [N] 0.2 1, contact pressure [Pa] , peripheral speed [m/s] Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 22

23 Time dependency of concentration Number concentrat. [cm -3 ] Start of Sanding process End of Sanding process Meas. time [s] 2KPU-paint on wood with Fe-Ad. Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 23

24 Time dependency of psd Number concentration density [cm 3 ] Partikeldurchmesser [nm] t = 10 s t = 15 s t = 20 s t = 25 s t = 30 s t = 35 s t = 40 s two-pack polyurethane without nanoparticle additives Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 24

25 Part. Size Distribution Number and volume density distribution of Laser Aerosol Particle Analyzer from 2KPU-paint with Fe-Additives Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 25

26 Results Swarf mass in comparison to the average number of total released particles with minimum and maximum spreads, based on a sanding area of 13 cm 2 Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 26

27 Results (TEM) TEM- investigations of the generated abrasive wear with embedded nanoparticles (PU with zinc oxide) Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 27

28 Results (TEM) PU with zinc oxide : 1 F080602TE08 200nm Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 28

29 Conclusions Particle release in worst case scenario (grinding) can cause nanoparticle concentrations in a model room (3 m height) comparable to heavy traffic road High Particle release < 100 nm independently if nanoparticle additives are present or not, dependent on the sanding process and hardness of polymer matrix Particle additives < 100 nm are embedded in abrasive wear (for investigated paint systems) Outlook Input of methodological results in standardization project of ISO/TC 229 DIS General Framework for Determining Nanoparticle Content in Nanomaterials by Generation of Aerosols Next step in life cycle approach: weathered until degradation paints -abrasion stress comparable to professional grinding Further investigations with more coatings and nanoparticles Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 29

30 Publication of the methods and results M.Vorbau, L.Hillemann, M.Stintz: Method for the characterization of the abrasion induced nanoparticle release into air from surface coatings. J. Aerosol Sci., 2009, 40, D. Göhler, M. Stintz, L. Hillemann and M. Vorbau: Characterization of Nanoparticle Release from Surface Coatings by the Simulation of a Sanding. Process. Ann. Occup. Hyg., Vol. 54, No. 6, pp , Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 30

31 Content Physical and Chemical Characterization ISO/TC 24/SC 4 Particle Characterization Composite materials in paint industry ISO standardization for powder testing Standardization needs Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 31

32 ISO standardization for powder testing ISO/TC 229, WG 2, PG 10, PL Michael Stintz: Nanotechnologies - Quantification of nano-object release from powders by generation of aerosols This International Standard provides requirements for selecting methods, measuring release and presenting data relevant to process applications of the material. The purpose of this standard is to determine nano-objects released from powders by measuring aerosols liberated after a defined aerosolization procedure. Nano-object characterization includes particle concentration and size distribution of the fraction aerosolized. Tribological methods are excluded where direct mechanical friction is applied to grind or abrade the material. Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 32

33 ISO/DIS Example methods Rotating drum and continuous drop methods Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 33

34 ISO/DIS Example methods Vortex Shaker method Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 34

35 ISO/DIS Example methods Dynamic methods General Framework Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 35

36 ISO/DIS Example methods Indipendent adjustable parameter method Device for adjustable dosing of small powder quantities Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 36

37 Definitions how to quantify nanoparticle release ISO/DIS Powder engineered nanomaterials require additional considerations because of the specific powder characteristics and nanoparticle aerosol physic. Some necessary selection and evaluation criteria of aerosol generation methods are: - Adjustable volumetric flow - Adjustable particle concentration - Adjustable dispersion energy input - Independency of energy input from volumetric flow and particle concentration - repeated powder agitation vs. singular treatment of powder portions - magnitude of tribo-electric charging Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 37

38 Content Physical and Chemical Characterization ISO/TC 24/SC 4 Particle Characterization Composite materials in paint industry ISO standardization for powder testing Standardization needs Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 38

39 Challenges from nanotechnology Communication with National Metrology Institutes, material scientists, colloidal chemists, medical and environmental toxicologists, exposure experts, regulatory institutes Definitions: e.g. nanomaterial, categories for risk assessment? Scenarios: static properties dynamic processes (e.g.particle release) SOPs: learn from industry with controlled conditions Standardized measurement methods: selection, traceability, errors Reference materials for what purpose? Guidance from/for whom? Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 39

40 ISO/TC 24/SC 4 Particle Characterization WG 16 (NWI for TR) Guide for the characterization of dispersion stability Scope will include: emulsions, suspensions and combinations of each other Stability = absence of change in specified properties over a given timescale User needs to define timescale, and what constitutes a significant change for his product (or process), e.g. weak flocculated systems are stable There is no direct measurement of "stability, relative change of properties (rather than absolute) may be sufficient Two different approaches: - monitoring property values over time; e.g. detect demixing by changes observed over real time by microscopy, photometry, acoustics, conductivity, tomography etc. - measuring a given property (such as ph), from which one predicts whether or not the system is stable, e.g. predict demixing by measuring zeta pot. over a shorter time scale Include a guide for picking the measurement(s) for various destabilization processes, and a short explanation and referring to corresponding standards. Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 40

41 EU Workshop Co-Nanomet 28 April 2010 Instruments, standard methods and reference materials for traceable nanoparticle characterisation Most Lecturers from ISO/TC24/SC4 Particle Characterization: T. Thornton (Micromeritics, USA): Terminology and standards for ENP characterisation G. Roebben (JRC-IRMM, EU): Metrology for particle sizing B. Sachweh (BASF, DE): Quality assurance and process control T. Kuhlbusch (IUTA, DE): ENP characterization in view of health studies NANO-CARE M. Hassellöv (University Gothenburg, SE): ENP sizing for environmental risk assessment P. Bowen (EPFL, CH): Comparing methods for measurements in liquid A. Rawle (Malvern, USA): Characterisation of NPs with DLS W. Witt (Sympatec, DE): Sizing with on-line methods A. Dukhin (Dispersion Technology, USA): Measuring interfacial prop. using electroacoustics R. Xu (Beckman Coulter, USA): Zeta-potential measurement D. Lerche (L.U.M., DE): Suspension stability Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 41

42 EU Workshop Co-Nanomet 29 April 2010 ISO/TC24/SC4 Particle Characterization G. Sem (TSI, USA): Survey on aerosol measurement techniques R. Aitken (IOM, UK): Exposure assessment in settings relevant to nanotechnologies A. Lamberty (JRC-IRMM, EU): Reference materials: concepts, applications and ex-amples V. Hackley (NIST, USA): Experiences with ENP reference materials Y. Mori (Doshisha Uni, JP): Preparation of sub-micrometer particles for reference materials M. Krumrey (PTB, DE): Size determination of NPs with SAXS H. Sakurai (AIST, Japan): Chairman aerosols F. Babick (TUD, DE): Chairman liquid media A. Jamting (NMI Sydney, Australia): Poster Interlab. Comparison Free Download: Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 42

43 Thank you Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 43

44 Definitions - Particles and Particle Systems ISO/TC 229 Nanotechnologies, JWG 1 Definitions, current state: Seminar on Standards and standardization - Brussels M. Stintz: Standards relevant to materials Particle characterization 44