1. Particle characterization
Chapter 6

2. Why determinate particle size
List three things that you know will be affected by particle size

3. My three things
Delivery of particles to the lungs
Solubility of active pharmaceutical compounds
Bulk density

4. What do you want to characterize
Particle
Size
Morphology
Material properties
Porosity
Density
Hardness/elasticity(later)
Surface properties
Chemical composition
Surface energy
Roughness
Powder
Particle distribution
Flowability/cohesion
Specific surface
Density
Porosity
Air content
Water content (later)

5. Size and Morphology Describe these two particle collections

6. Size and Morphology Different descriptive terms for particles
Particle form
spherical, ellipsoid, granular, blocky, flaky, platy,prismodal, rodlike, acicular, needle shaped, fibrous irregular,dendrites, irregular, agglomerates
But also particle surface
Smooth, spotty, rough, porous, with cracks, hairy

7. Size and Morphology Measurement of particle size
Reduce to known geometry
Volume
Cubes
Spheres
Ellipsoids
Area
Circles
Squares
Ellipses
Lengths
Characteristic lengths
Feret and Martin diameters
Relate to the geometry
Fit into the geometry
Have equal Volume or Area
Have equal properties
A= Projected a rea
P=Perimeter
d=equivalent diameter
S=surface area
V=volume

8. Size and Morphology Descriptors based on diameters of circles
dcirc=Diameter of circumscribed minimum circle
dinsc=Diameter of inscribes maximum circle
deq=Diameter of the circle having same area as projection area of particle
Shape descriptor:Circularity
deq/dcirc
Lägg till shape faktorerna på tavlan

9. Size and Morphology More descriptors according to the same principles
Namn
Definition
Formula
Volume diameter
Diameter of a sphere having the same volume as the particle
Surface diameter
Diameter of a sphere having the same surface as the particle
Surface volume diameter
Diameter of a sphere having the same surface to volume ratio as the particle
Projected area diameter
Diameter of the circle having the same area as the projection area of particle
Perimeter diameter
Diameter of the circle having the same perimeter as the projection peramiter of particle

10. Size and Morphology Feret and Martin diameter
Df0
The Feret diameter the distance between two tangents to the contour of the particle in a well defined orientation.
The Martin diameter, is the length of a line that divide the area of the particle into two equal halves.
Normally measured
Mean= the mean over several orientations
Y=largest
X=smallest
Elongation= Y/X
Dm0

11. Size and Morphology Unrolled diameter
The mean chord length through the center of gravity of the particle

12. Size and Morphology Diameter Defined from equal properties
Drag diameter
Diameter of a sphere having the same resistance to motion as the particle in a fluid of the same viscosity and the same speed
Free-falling diameter
Diameter of a sphere having the same density and the same free-falling speed as the particle in a fluid of the same density and viscosity
Stoke diameter
The free falling diameter of a particle in the laminar flow region
Aerodynamic diameter
the diameter of a sphere of unit density (1g/cc) that has the same gravitational settling velocity as the particle in question.
Equivalent light-scattering diameter
Diameter of the sphere giving the same intensity of light scattering as that of a particle, obtained by the light-scattering method

13. Size and Morphology Stoke diameter
For small particles <0.5m Brownian motions counteract gravitational forces and the system will be stable
For larger particles
Density matching will hinder sedimentation
msolvent*g
Brownian motion a
mpart*g

14. Size and Morphology Diameter Defined from equal properties contin..
Equivalent light-scattering diameter
Diameter of the sphere giving the same intensity of light scattering as that of a particle, obtained by the light-scattering method
Sieve diameter
The diameter of the smallest grid in a sieve that the particle will passe through

15. Size and Morphology From descriptors
Elongation: L/B or dferet(max)/dferet (min)
Circularity: for example dins/dcirc
Sphericity (Wandells):

16. Size and Morphology Form descriptors
Form factors: f/k will describe the form
Space Filling Factor: The ratio between the area of a circumscribed rectangle or circumscribed circle of the image and that of the particle eg A/LB eller 4A/πr2
F/k mellan 3-20

17. Material properties Density
True particle density: The density of the material
Apparent particle density: Density of the particle when inner porosity is included
Effective or aerodynamic particle density: Density if outer porosity is included. Related to the density that a air or gas stream will measure.

18. Surface properties Particle surface
Roughness of the surface
Composition
Surface energy
Influences
Stability
Total area
Particle size reduction
Adsorption of other substances to the surface
Aggregation
Release of adsorbed material

19. Surface properties To evaluate surfaces properties
ESCA, XPS - Composition
FTIR - Composition
AFM- Surface morphology and surface energy
Raman microscopy- composition
Electron microscopy -Surface morphology
Evaluation of Ascorbyl Palmitate-loaded NLC Gel using Atomic Force Microscopy
V.Teeranachaideekul.1,2, S. Petchsirivej3,4 , R.H. Müller1, V.B. Junyaprasert2

20. Surface properties To evaluate surface energy - Contact angles
L/V
S/V
Gives information on how easily a liquid wets a surface.
Low contact angle with water for hydrophilic surfaces.
Contact angle hysteresis:
Chemically heterogeneous surface.
Surface roughness.
Surface porosity
Surface changes when wetted.

21. Assignments particles Task
Test and compare two different techniques for size determinations (half a day)
Microscopy
Light scattering
Answer the questions in the assignment description on a seminar (Tue 28 Apr 13.15)
As usuell hand in a short technical note

22. Assignments particles Practical issues
Do the assignment in groups of three
Use our sample or your own
Microscopy use the microscope to take picture but do the major part of the analyses afterwards Image J is a free program

23. Size distribution Particle size distribution
Why is the mean value not enough to describe particle size distributions
How can we describe the distribution
Based on what properties
Based on what type of statistic distribution

24. Size distribution Type of distributions
Different type of diameters
Different type of distribution
Number (0)
Length (1)
Area (2)
Volume (3)
Weight (w) =V*
How will these differ from one another?
How do you calculate the mean particle size
Can you transfer mean particle size between the different distributions?

25. Size distribution Average particle size
Number mean length diameter d(1,0) 2
Number mean surface diameter d(2,0)
2,16
Number mean volume diameter d(3,0)
2,29
Weighted mean length diameter d(3,0)
Length surface mean diameter d(2,1)
2,33
Length volume mean diameter d(3,1)
2,45
Surface Volume mean diameter d(3,2)
2,57
weight moment mean diameter d(4,3)
2,72
Förkklara weight

26. Size distribution Different distributions

27. Size distribution Type of statistic distribution
Normal distribution
Log Normal
Rosin–Rammler (Weibull) Distribution

28. Size distribution Special properties of log distributions
If the number is log distributed so is the length, surface, and volume
With the same geometric mean deviation
Hatch-Choate relationships will transfer one type of mean diameter into another

29. Size distribution Description of particle size distribution
Mean diameter
Standard mean,
Geometric mean
variability
Standard deviation
Geometric standard deviation
Skewness

30. Powder Specific surface
Surface per weight
Factors that increase surface area
Decrease in particle size
Increase in surface roughness
Inner porosity (if available)
Method dependent parameter
Permeatry
Gas adsorption
Gas diffusion
Porosimetery
Importance
Dissolution
Chemical reactions
Adsorption of other molecules
Flow though particle beds

31. Powder Density, air content and porosity
Density (b)= weight of powder/Volume of powder
Air content= air in pores(entrapped air) and air in between particles (void air)
Porosity
In particle
Between particles
Sambanden på tavlan glöm inte detta

32. Powder Flow properties and powder density
Angle of repose
Bulk density
Tapping density
Carrs index
Hausner ration
Flow character
Angle
Carrs index
Very good
<20
5-15
Good
20-30
12-16 Ok
18-21
Poor
30-34
25-35
Very poor
33-38
Extremely poor
>40