Chapter 6 Understanding the views
Page 6-6 MAN 0384
Distribution – shows the type of distribution the analysis has used. Options
include change from volume to surface area, length or number. Remember
that the Mastersizer measurement is fundamentally a measurement of the vol-
ume distribution - transforming the result into a surface, length or number dis-
tribution is a mathematical process that may amplify any error in the original
result, especially at the fine end of the size distribution.
Uniformity – a measure of the absolute deviation from the median.
Here d(x,0.5) is the median size of the distribution (where x is replaced by v, s,
l or n) and d
i
and x
i
are respectively the mean diameter of, and result in, size
class i.
Specific Surface Area (SSA) – the total area of the particles divided by the
total weight.
where V
i
is the relative volume in class i with mean class diameter of d
i
and p is
the particle density.
If the SSA is used, it is important that the density of the material is defined (on
the SOP Wizard’s Material dialogue). This figure is a mathematical calcula-
tion based on the assumption that the particles are both spherical and non-
porous.
Uniformity
X
i
dx0.5,()d
i
–
∑
dx0.5,()X
i
∑
------------------------------------------------=
SSA
6
V
i
d
i
-----
∑
pV
i
∑
-----------------
6
pD 32,[]
---------------------==
MAN0384-1.0 Mastersizer 2000.book Page 6 Tuesday, March 20, 2007 8:56 AM
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