Powder 2005

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Powder 2005

  1. 1. Materials Characterization Lab www.mri.psu.edu/mcl Particle Characterization R.I. Malek Materials Research Institute University Park, PA 16802
  2. 2. Materials Characterization Lab www.mri.psu.edu/mcl Outline • Particle Characterization Laboratory •Techniques •Particle Sizing Static and Dynamic Light Scattering, Sedimentation, Microscopy, Sieve analysis. •Zeta Potential Electrophoresis, Electroacoustic. • Porosity, Surface Area, Density. • Rheology • Instruments •Some Applications •New Instruments
  3. 3. Materials Characterization Lab www.mri.psu.edu/mcl Particle Characterization Laboratory Extensive laboratory services for routine analysis and QA/QC. The cooperative alliance with other laboratories across the University provides expanded access to high-tech equipment for all testing needs. Atomic Force Microscopy Particle Size Distribution Malvern Mastersizer S - Wet and Dry Laser Diffraction (0.05 to 900 mm) • Malvern Zetasizer Nanosizer (0.6 nm to 6 mm) • Horiba CAPA 700 Centrifugal Sedimentation Particle Size Analyzer (0.01 to 300 mm) • Hosokawa Micron Air Jet Sieve • Mercury Intrusion Porosimetry Pascal 140, 440 Mercury Porosimeter (0.004 mm -116 mm) • BET Surface Area and Porosimetry Micromeritics Gimini (5 points BET Analysis) • Micromeritics ASAP 2020 for full adsorption/desorption isotherm and pore size distribution. • Zeta Potential Brookhaven ZetaPALS Zeta Potential Analyzer • Coulter Delsa 440SX Zeta Potential Analyzer • Electro/Acoustic Spectroscopy Zeta Potential and Particle Size Analyzer • Chemisorption and Catalysis Micromeritics AutoChem 2920, TPD, TPO, TPR, pulse chemisorption, heat of adsorption (-70 °C to 1100 °C) . • Helium Pycnometry Rheology CSL Instruments Rheometer • TA Instruments Thermal Analysis System (Air-Nitrogen-Argon-Specialty gas) Differential Scanning Calorimeter (DSC) -70oC - 600oC • Thermogravimetric/Mass Spectrometry Analysis (TGA/Mass) 1000oC, 1-300 amu • Simultaneous DSC/TGA or DTA/TGA 1500oC • – Contact R. Malek – (814) 865-7341 – RQM@PSU.EDU – –
  4. 4. Materials Characterization Lab www.mri.psu.edu/mcl Particle Sizing • Centrifugal Sedimentation. • Static Light Scattering (SLS). • Dynamic Light Scattering (DLS) Quasi Elastic Light Scattering (QELS) Photon Correlation Spectroscopy (PCS). • Electroacoustic (the ultrasound equivalent to light scattering). • Electrozone Sensing.
  5. 5. Materials Characterization Lab www.mri.psu.edu/mcl Static Light Scattering.
  6. 6. Materials Characterization Lab www.mri.psu.edu/mcl Instruments at MRL Malvern Mastersizer S - Wet and Dry Laser Diffraction (0.05 to 900 µm)
  7. 7. Materials Characterization Lab www.mri.psu.edu/mcl Dynamic Light Scattering (DLS) Quasi Elastic Light Scattering (QELS) Photon Correlation Spectroscopy (PCS) relies on measuring the Brownian motion of small particles and relating this to the hydrodynamic diameter, dh of the particle system by means of the Stokes-Einstein equation: d h = kT/3πηD where k is Boltzmann's Constant, T is the absolute temperature, η is the viscosity of the medium and D is the diffusion coefficient.
  8. 8. Materials Characterization Lab www.mri.psu.edu/mcl Malvern Zetasizer Nanosizer (0.6 nm to 6 µm)
  9. 9. Materials Characterization Lab www.mri.psu.edu/mcl Brownian Motion Particles move or diffuse as a consequence of thermally driven solvent collisions. Translational diffusion is not the same as linear diffusion.
  10. 10. Materials Characterization Lab www.mri.psu.edu/mcl The diffusion coefficient (D) is calculated by fitting the correlation curve to an exponential function G(t), with D being proportional to the lifetime of the exponential decay where I is the scattering intensity, to is the initial time, t is the delay time, A is the amplitude or intercept of the correlation function, B is the baseline, D is the diffusion coefficient, and q is the scattering vector.
  11. 11. Materials Characterization Lab www.mri.psu.edu/mcl Classical vs. Backscatter
  12. 12. Materials Characterization Lab www.mri.psu.edu/mcl Backscatter Benefits Increased scattering volume and variable cell position Dilute low MW Concentrated high samples MW samples • Enhanced Sensitivity • Higher Concentrations • Larger Size Range • Better Reproducibility
  13. 13. Materials Characterization Lab www.mri.psu.edu/mcl Typical Analysis Algorithms • Cumulants – Assumes a single exponential decay, i.e. one particle size – Gives only the Z average size and polydispersity index – Recommended by International Standards Organization G(t) = B + A e-2q2D • Multimodal – Fits the curve to the optimal number of exponentials G(t) = B + ΣA e-2q2D
  14. 14. Materials Characterization Lab www.mri.psu.edu/mcl Ideal Samples Cumulant & multimodal distribution results are consistent
  15. 15. Materials Characterization Lab www.mri.psu.edu/mcl Typical Samples Cumulant & multimodal distribution results are NOT consistent
  16. 16. Materials Characterization Lab www.mri.psu.edu/mcl Hydrodynamic radius By definition, the DLS measured radius is the radius of a hypothetical hard sphere that diffuses with the same speed as the particle under examination. In practice, particles are solvated. As such, the radius calculated from the diffusional properties of the particle is indicative of the size of the dynamic hydrated/solvated particle.
  17. 17. Materials Characterization Lab www.mri.psu.edu/mcl High Concentration - Issues • Multiple Scattering - light scattered from diffusing particles is re-scattered by other particles => size reduction. • Excluded Volume - the presence of other particles blocks or hinders free particle diffusion => size increase. • Aggregation Equilibrium - concentration dependent aggregation of primary particles => increase distribution, polydispersity and average size. • Electrostatic Interactions - overlapping electric fields lead to interactions that can influence the translational diffusion => change in size.
  18. 18. Materials Characterization Lab www.mri.psu.edu/mcl High Concentration - Solutions • Use the bulk, rather than the solvent, viscosity. • Use salt. • Dispersion: Chemical dispersion: Dispersants. Mechanical dispersion: Sonication: Excess thermal and mechanical agitation increases the Possibility of collisions between particles causing agglomeration, Rule: Use absolute minimum mechanical agitation and in short periodic bursts.
  19. 19. Materials Characterization Lab www.mri.psu.edu/mcl The solution, add salt!! 600 1/k 500 Hydrodynamic size Hydrodynamic radius (nm) 400 300 200 100 0 0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10 100 Ionic strength (M)
  20. 20. Materials Characterization Lab www.mri.psu.edu/mcl Sedimentation uSt= (r s - r f)g D² h 18 f b Rate dependent on fd density Underestimates size fg Limited dynamic Liquid range Slow
  21. 21. Materials Characterization Lab www.mri.psu.edu/mcl Horiba CAPA 700 Centrifugal Sedimentation Particle Size Analyzer (0.01 to 300 µm)
  22. 22. Materials Characterization Lab www.mri.psu.edu/mcl Electrozone Method Conductivity +- changes as particle passes through aperture Requires electrolytic solution & calibration Problems w/porous materials
  23. 23. Materials Characterization Lab www.mri.psu.edu/mcl Coulter Counter
  24. 24. Materials Characterization Lab www.mri.psu.edu/mcl Hosokawa Micron Air Jet Sieve Sieve Analysis Solids only Large particles 38 µm min Inexpensive Limited accuracy, resolution, precision
  25. 25. Materials Characterization Lab www.mri.psu.edu/mcl Technique and Dynamic Range Sieve Microscope Sedimentation Electro zone PCS Acoustic Image Analysis Diffraction .001 .01 .1 1µm 10 100 1000
  26. 26. Materials Characterization Lab www.mri.psu.edu/mcl Zeta Potential Slipping plane The liquid layer surrounding the Particle with particle exists as two parts; an negative inner region (Stern layer) where surface the ions are strongly bound and charge an outer (diffuse) region where they are less firmly associated. Stern layer Within this diffuse layer is a notional boundary within which the particle Diffuse layer -100 { acts as a single entity. - Surface potential Stern potential mV Zeta potential The potential at this boundary is the ZETA POTENTIAL 0 Distance from particle surface
  27. 27. Materials Characterization Lab www.mri.psu.edu/mcl Why Is Zeta Potential Important Particles do not interact electrostatically according to the magnitude of their surface charge, but according to the zeta potential at the slipping plane. The magnitude of the zeta potential gives an • indication of the stability of the system - If all the particles have a large negative or positive zeta potential they will repel each other and there is dispersion stability. - If the particles have low zeta potential values then there is no force to prevent the particles coming together and there is dispersion instability (aggregation).
  28. 28. Materials Characterization Lab www.mri.psu.edu/mcl Instruments at MRL Brookhaven ZetaPALS Zeta Potential and Particle Size Analyzer
  29. 29. Materials Characterization Lab www.mri.psu.edu/mcl Coulter Delsa 440SX Zeta Potential Analyzer
  30. 30. Materials Characterization Lab www.mri.psu.edu/mcl Electro/Acoustic Spectroscopy Zeta Potential and Particle Size Analyzer
  31. 31. Materials Characterization Lab www.mri.psu.edu/mcl Acoustic Attenuation Acoustic wave out Acoustic wave in Is I0 f Frequency f Frequency Suspension DL ⎛ ⎞ I 1 α= lo g ⎜ ⎟ 0 Attenuation ∆L ⎝ S⎠ I • The double layer is disturbed by an ultrasonic wave. The displacement of the ionic cloud with respect to the surface creates a dipole moment. The sum of these dipole moments over many particles creates an electrical field which is sensed by a receiving antenna immersed in the sample.
  32. 32. Materials Characterization Lab www.mri.psu.edu/mcl Pascal 140, 440 Mercury Intrusion Porosimeter Washborn Equation Washburn-equation is:
  33. 33. Materials Characterization Lab www.mri.psu.edu/mcl Mercury Porosimetry of powders
  34. 34. Materials Characterization Lab www.mri.psu.edu/mcl Micromeritics Gemini BET Surface Area Analyzer
  35. 35. Materials Characterization Lab www.mri.psu.edu/mcl Helium Pycnometer
  36. 36. Materials Characterization Lab www.mri.psu.edu/mcl Carrimed CSL Rheometer
  37. 37. Materials Characterization Lab www.mri.psu.edu/mcl
  38. 38. Materials Characterization Lab www.mri.psu.edu/mcl New Instruments ASAP 2020 Accelerated Surface Area and Porosimetery Analyzer. Unique Capability • Two Independent vacuum systems. • Oil-free “dry” vacuum pump. • Intelligent degas system. • New long-duration cryogen system. • Automated selection of gas • Ability to connect to a mass spec.
  39. 39. Materials Characterization Lab www.mri.psu.edu/mcl ASAP 2020 Chemisorption Option Uses the static volumetric technique to determine the percent metal dispersion, active metal surface area, size of active particles, and surface acidity of catalyst materials.
  40. 40. Materials Characterization Lab www.mri.psu.edu/mcl AutoChem II 2920 •Adsorption Pulse Chemisorption •Temperature •Programmed Studies –TPR –TPD –TPO
  41. 41. Materials Characterization Lab www.mri.psu.edu/mcl Source Material • Instrument Manuals. • Several books on specific materials. • journals. • Conferences
  42. 42. Materials Characterization Lab www.mri.psu.edu/mcl Acceptable sample forms: Powders Suspensions
  43. 43. Materials Characterization Lab www.mri.psu.edu/mcl Charges • Instrument Charge = $7/Sample. • Training, data interpretation, sample set-up, etc) = $30/hr. • Consultation time to discuss your samples, data, etc is free.
  44. 44. Materials Characterization Lab www.mri.psu.edu/mcl Campus resources- people • Raafat Malek, 109 Materials Research Lab Building, Hastings Road 865-7341 rqm@psu.edu • Jeff Shallenberger, 196 MRI Bldg 865-0337 jxs124@psu.edu Other resources: • www,mri.psu.edu/mcl/techniques/thermal.asp (links, applications, etc) • MRI links to publications and abstract (Web of Science) searching (www.mri.psu.edu/linkspubs/) • The Libraries (http://www.lias.psu.edu/)

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