Mastersizer S, Mastersizer 2000 and Mastersizer 3000: Method transfer how to get the same results on all three systems

Transcription

1 Mastersizer S, Mastersizer 2000 and Mastersizer 3000: Method transfer how to get the same results on all three systems

2 Overview Introduction to particle sizing Introduction to laser diffraction Evolution of laser diffraction systems Method transfer Dispersion Analysis Case studies

3 Introduction to particle sizing A particle can be described as a discrete subportion of a substance, e.g. solid particles liquid droplets or gas bubbles Laser diffraction measures particles in the size range from nanometres to millimetres

4 How do we describe the size of particles Equivalent spheres Maximum length Minimum length Min. length Max. length Max. length Min. length

5 How do we describe the size of particles Equivalent spheres Maximum length Minimum length Sedimentation rate Sedimentation rate Max. length Min. length Sedimentation rate

6 How do we describe the size of particles Equivalent spheres Maximum length Minimum length Sedimentation rate Sieve aperture Sieve aperture Max. length Min. length Sedimentation rate Sieve aperture

7 How do we describe the size of particles Equivalent spheres Maximum length Minimum length Sedimentation rate Sieve aperture Surface area Surface area Max. length Min. length Sedimentation rate Sieve aperture Surface area

8 How do we describe the size of particles Equivalent spheres Maximum length Minimum length Sedimentation rate Sieve aperture Surface area Volume Volume Max. length Min. length Sedimentation rate Sieve aperture Surface area

9 The particle size distribution Laser diffraction measurements produce volume based particle size distributions 10 8 Volume density / % Size classes / m

10 INTRODUCTION TO LASER DIFFRACTION

11 The diffraction pattern

12 Dependence of diffraction pattern on particle size Incident light Incident light Large Small angle scattering angle scattering 5 microns 800 nanometres Dr Kevin Powers, PERC, University of Florida

13 Scattering models: Mie Theory Models the interaction of light with matter Assuming that the particles are spherical Assuming that it is a two phase system Valid for all wavelengths of light and all particle sizes Predicts the dependence of scattering intensity on particle size Predicts that secondary scattering is observed for small particles For particles smaller than about 50μm Mie theory offers the best general solution ISO13320

14 Mie Theory: Predicted scattering Refracted light

15 Mie Theory: Optical properties Absorption.. the Mie theory offers the best general solution. ISO 13320: 2009

16 How do we get the size distribution?

17 Reporting and interpreting the results Particle size distribution Volume based % Volume Dv10 D[3,2] Dv50 D[4,3] Dv90 Diameter Percentiles Averages, weighted by surface area or volume

18 EVOLUTION OF LASER DIFFRACTION SYSTEMS

19 Evolution of Laser Diffraction Particle Sizing Extremely successful - 10,000 s users worldwide Routine tool in many industries versatility and ease of use are key Mastersizer 3000 is the latest generation

20 A basic laser diffraction system

21 A basic laser diffraction system The optics are arranged so that particles of the same size scatter light to the same part of the detector array

22 Optical systems: Mastersizer S Lens 300RF 300mm 1000mm (long bench) Size range 0.05 to 880um 0.5 to 880um 4.2 to 3480um

23 Optical systems: Mastersizer 2000 red light Size range: 0.1 to 2000um

24 Optical systems: Mastersizer 2000 blue light The scattering intensity observed for sub-micron particles is increased by using 466nm blue light source Size range: 0.02 to 2000um

25 Optical systems: Mastersizer 3000 red light Back scatter detectors Measurement cell Focal plane detectors Side scatter detectors Precision folded optics Size range: 0.1 to 3500um 633nm red laser

26 Optical systems: Mastersizer 3000 blue light Back scatter detectors Measurement cell 470nm blue light source Side scatter detectors Size range: 0.01 to 3500um

27 Wet dispersion units Dispersion conditions Ultrasound Stirrer speed Concentration Dry dispersion SAMPLE DISPERSION

28 Method development and method transfer A laser diffraction measurement requires a representative sample, dispersed at an adequate concentration in a suitable liquid or gas <USP429> Method development must define appropriate Sampling Dispersion Measurement conditions

29 Wet dispersion units Large volumes: 600ml to 1000ml Medium volumes: 80ml to 120ml Small volumes: 6 to 18ml

30 Method transfer: dispersion conditions Agglomerated Dispersed

31 Method transfer: dispersion conditions Size / um Stirring Ultrasound After Ultrasound Measurement no. Dx (10) (μm) Dx (50) (μm) Dx (90) (μm)

32 Method transfer: ultrasound Ultrasound titration ground glass In-line sonication can reduce required ultrasound duration MS2000 Dv90 MS3000 Dv Dv90 / µm Ultrasound duration / s

33 Method transfer: stirrer speed MS3000 dispersion units have a combined pump and stir

34 Method transfer: stir speed titration 180 d10 dv50 d Particle size / μm Stir speed / rpm For coarse or dense materials particle size will increase with stir speed until all particles are suspended A stable particle size is obtained above 2500rpm

35 Method transfer: concentration Obscuration is a measure of concentration The low limit is defined by signal to noise ratio and measurement reproducibility The high limit is defined by multiple scattering

36 Multiple scattering If we add too much sample the results may be affected by multiple scattering This generally affects samples smaller than 10μm High angle detectors Measurement cell Detector Low angle detectors

37 Multiple scattering If we add too much sample the results may be affected by multiple scattering This generally affects samples smaller than 10μm High angle detectors Measurement cell Detector Increase in scattering angle Low angle detectors

38 Achieving comparable results: concentration 8 Particle Size Distribution Volume (%) Particle Size (µm) Averaged 3%, 18 March :32:25 Averaged 5%, 18 March :35:46 Averaged 9%, 18 March :42:01 Averaged 13%, 18 March :49:02 Averaged 17%, 18 March :53:59

39 Achieving comparable results: obscuration titration Comparison of MS2000 and MS3000 results vs. obscuration MS3000 MS Dv10 / µm Obscuration / %

40 Wet dispersion method transfer summary Ultrasound efficiency will vary with: Power and frequency of generator Mechanism: in-line or dip-in probe Volume of dispersion unit Concentration Different systems show multiple scattering at effects different obscurations Stirrer speed Stir speed titration may be required to achieve comparability

41 Dry dispersion units Mastersizer S Mastersizer 2000 Mastersizer 3000

42 The Aero S has a range of different tray designs to aid method transfer Micro tray Large volume tray Macro tray General purpose tray with hopper

43 Dry powder dispersion: Mechanisms Energy/aggressive Importance of each mechanism depends on: Disperser geometry Flow rate or pressure drop Material type Higher impact energies may improve the dispersion effectiveness Needs to be balanced against the risk of particle break-up

44 Dry powder dispersion: Disperser geometries Standard Venturi High-Energy Venturi

45 Method transfer: pressure titration Make measurements at 4, 3, 2, 1, 0.5 and 0.1 bar. Investigate the effect of pressure on the state of dispersion

46 Method transfer: comparing dispersers Aero Standard Aero High Energy Wet Dispersion Dv50 / um Air Pressure / bar

47 Method transfer: Aero vs Sirocco Dv50 / um Aero Standard Aero High Energy Scirocco Wet Dispersion Air Pressure / bar

48 Dry dispersion method transfer summary Different disperser mechanisms are used Carry out a pressure titration Choose the pressure that gives equivalent and robust results Choose the best tray option for your material Volume of material to be measured Flowability Different vibration mechanisms are used Choose the vibration rate that gives a consistent flow within the obscuration range.

49 ANALYSIS

50 Analysis: Optical properties Calcium carbonate sample Optical properties Refractive index: Absorption: 0.1 MS3000 MS2000 Dv 10 Dv 50 Dv 90 Residual Weighted residual MS MS Average Standard deviation %RSD Volume frequency / % Size / m

51 Analysis: Assessing the data fit Residual Weighted residual Light Energy Data Graph - Light Scattering Residual Weighted residual Detector Number Fit data(weighted) calcium carbonate, 27 January :31:52

52 Analysis: Assessing the data fit Residual Weighted residual Data Graph - Light Scattering Light Energy Residual Weighted residual Detector Number Fit data(weighted) calcium carbonate, 27 January :31:52

53 The optical property optimiser (OPO) Offers a quick way to adjust optical properties and assess the fit and result

54 Analysis: Correct optical properties Calcium carbonate sample Optical properties Refractive index : Absorption: 0.01 MS3000 MS2000 Dv 10 Dv 50 Dv 90 Residual Weighted residual MS MS Average Standard deviation %RSD Volume frequency / % Size / m

55 Analysis: Models

56 Analysis: Particle shape

57 Analysis: MS2000 emulated analysis

58 CASE STUDIES

59 Case study: Calcium carbonate 10 8 MS3000 MS2000 MSS Volume frequnecy / % Size / m Correct optical properties Refractive index between 1.53 and 1.65, absorption 0.01 No multiple scattering 5% to 10% obscuration

60 Case studies across the size range Silicon carbide sample Wet dispersion; Hydro G, Hydro LV (3500rpm)

61 Case studies across the size range Pigment sample Wet dispersion, Hydro S, Hydro MV (2100rpm)

62 Case studies across the size range Calcium carbonate Wet dispersion, Hydro MU, Hydro EV

63 Case studies across the size range Emulsion sample, wet dispersion, Hydro S, Hydro MV 10 Particle Size Distribution Volume (%) Particle Size (µm) emulsion, 11 June :55:38

64 Examples at the extremes of the size range Coffee Dry dispersion, Aero S standard venturi, Scirocco

65 Summary The optical systems of diffraction systems have evolved to measure a wider particle size range: measurements at narrower angles due to smaller detector elements more high angle scattering data due to more sensitive detector elements Additional lower wavelength light sources The dispersion units have evolved to Provide more efficient dispersion Provide dry dispersion mechanisms tailored to the robustness of the material By understanding the materials state of dispersion, excellent comparability can be achieved