_14
\
,
FREEZE-DRYING
of the work
had undertaken at Cambridge in an effort to determine the actual
of damage which oCcur during the freeze—drying process. In any such investigation
î
it;_;is «necessary Îto …di‘erentiate between each stage of the process
and the, possible
_‘
sources of =,damage.
therefore began by studying,the e‘ect of protective additiveson
?
salt concentration and crystalsation.
This was followed by investigating the protection
such
stage ofthe:freeze—drying process… The latter work is
discussed by Brofessonreaves in anothersection of this book.
'
:
-
,,
,_The apparatus us;äd;to,investigate the physical phenomena which occur… on cooling
and
-
that as used by Rey(l960). It consisted of a stainless steel
blochwith…foun
holes or cells(each 37mm X 12 mm diam.). Two cells each contained 5 ml
of theaqueous selution;under test, whilst the other pair each contained 4 ml of distled
"
waterrwhich
Absolute and di"erential temperatures were
measured at a, depthof 3em
of copper—constantan thermocouples. The cellfor
conductivity
two stainless steel wires; .3 cm in length and separated
by a,
cm,; fed.with
current of 1,000 cycles per sec. Freezing at a rate of
per sec,was,achieved by=in‘1mersing the cylinder in the gas space of a
Linde LNR—25 refrigeraton
a similar rate—was achievedby placing the block
irLan
Simultaneous recordings of conductivity,
temperature and differential temperature were obtained on a Kipp Micrograph Recorder.
Throughout the experiment expanded polystyrene was used as insulation against condensa—
.
tion of atmospheric moi5ture,
_.
—
_
,
The effect of freezing
solution containing an _electrolyte may be represented by the
thermal analysis of sodium chloride (gure 3). on cooling below O°C ice separates out
1
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FIGURE?»Thermalanalysrsofa09/solutionofSOd1umchlondemwaterThearrowsmd1catethe
:
Œræü0n0f0hage(ŒeaveS&DaVles, 1955)
‘
‘
\
,
FREEZE-DRYING
of the work
had undertaken at Cambridge in an effort to determine the actual
of damage which oCcur during the freeze—drying process. In any such investigation
î
it;_;is «necessary Îto …di‘erentiate between each stage of the process
and the, possible
_‘
sources of =,damage.
therefore began by studying,the e‘ect of protective additiveson
?
salt concentration and crystalsation.
This was followed by investigating the protection
such
stage ofthe:freeze—drying process… The latter work is
discussed by Brofessonreaves in anothersection of this book.
'
:
-
,,
,_The apparatus us;äd;to,investigate the physical phenomena which occur… on cooling
and
-
that as used by Rey(l960). It consisted of a stainless steel
blochwith…foun
holes or cells(each 37mm X 12 mm diam.). Two cells each contained 5 ml
of theaqueous selution;under test, whilst the other pair each contained 4 ml of distled
"
waterrwhich
Absolute and di"erential temperatures were
measured at a, depthof 3em
of copper—constantan thermocouples. The cellfor
conductivity
two stainless steel wires; .3 cm in length and separated
by a,
cm,; fed.with
current of 1,000 cycles per sec. Freezing at a rate of
per sec,was,achieved by=in‘1mersing the cylinder in the gas space of a
Linde LNR—25 refrigeraton
a similar rate—was achievedby placing the block
irLan
Simultaneous recordings of conductivity,
temperature and differential temperature were obtained on a Kipp Micrograph Recorder.
Throughout the experiment expanded polystyrene was used as insulation against condensa—
.
tion of atmospheric moi5ture,
_.
—
_
,
The effect of freezing
solution containing an _electrolyte may be represented by the
thermal analysis of sodium chloride (gure 3). on cooling below O°C ice separates out
1
—.
joM
:
.'
‘
'
,
.
,.
\M
"
_.
'
-
.—
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«
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.
FIGURE?»Thermalanalysrsofa09/solutionofSOd1umchlondemwaterThearrowsmd1catethe
:
Œræü0n0f0hage(ŒeaveS&DaVles, 1955)
‘
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