Thermal analysis law determination for medicinal
purposes high polymer vitrification transition temperature
1. Experimental goal
1. Further familiar grasps the thermal analysis
meter the use
2. Understands the high polymer vitrification
transition temperature the determination method
Second, basic principle
When test specimen when has mechanics change of state,
for example by glass condition transformation for high elasticity
condition, although not remarkable heat absorption or exothermic
phenomenon, but the specific heat has the sudden change, displays in
the difference heating curve is the baseline suddenly change.
Therefore, the bad heating curve shape and the position may
reflect the test specimen interior condition the change.
The high polymer (Tg) around occurs in the vitrification
transition temperature compared to the heat capacity change, DTA (or
DSC) the curve usually is presents to the heat absorption direction
transition, occasionally presents the smaller heat absorption peak.
Like the chart 2-1 (a), (b), determines the vitrification
transition temperature method as follows by the chart: Chart 2-1 vitrification transition temperature
determination
(a) stage shape change situation; (b)
the stage shape change appears the peak in the high temperature side
the situation 1st, vitrification transformation
initial temperature Tig reads takes the method:
The straight line and lengthens which from the low temperature
侧基 alignment high temperature side directs through the
vitrification transformation stage shape change partial rate of curve
biggest spot institute 切线the point of intersection temperature.
2nd, vitrification transformation center point
temperature Tmg reads takes the method:
In the x-direction and the low temperature side, the high
temperature side baseline extends long-line or and so on the distance
straight line and the vitrification transformation step change partial
curves point of intersection temperature.
3rd, vitrification transformation termination
temperature Teg reads takes the method:
The straight line and lengthens which from the high temperature
lateral low temperature side directs through the vitrification
transformation step change partial rate of curve biggest spot
institute 切线the point of intersection temperature. Moreover,
appears the peak when the vitrification transformation stage shape
change high temperature side, then the extrapolation vitrification
transformation termination temperature, is takes the high temperature
baseline the straight line and which lengthens to the low temperature
side directs through the peak high temperature side rate of curve
biggest spot institute 切线the point of intersection temperature.
Third, instrument and drugs
DZ3320A differential motion thermal analysis meter
(purchase relation: Zhou Yiguang 13.851485841 billion
zyg@njdzyq.com)
Indium (standard thing) high polymer
Fourth, sequence of operation
1st, the determination must carry on according to the
below process
Before (1) determines the test specimen to the
temperature for 23±2 ? the relative humidity is under 50±5%
condition lays aside above 24h, adjustment test specimen condition.
(2) the test specimen mix is even, should have the
representation, weighing approximately 10mg (called to 0.1 mg), when
the test specimen like includes the massive auxiliaries, the high
polymer quantity should include 5 ~ 10 mg.
(3) loads the test specimen the aluminum 坩锅 center, puts in
the thermal analysis meter to heat up to is higher than the
vitrification transformation termination temperature approximately 30
? after maintains 10 minutes, suddenly cools to is lower than
approximately 50 ?(crystalless condition test specimen) the
vitrification transition temperature. Regarding crystallization
test specimen, then take fuses the peak termination temperature as.
(4) determines the condition: The elevation of temperature
speed is 20 ?/min, passes the nitrogen (10 ~ 50ml/min) to guard
against the oxidation.
Because the vitrification transition temperature and the test
specimen heat up processing and the experimental condition related,
therefore processing and the determination must carry on under the
identical condition.
2nd, according to tests a DZ3320A differential thermal analysis
meter operation, carries on the differential thermal analysis.
The test specimen crucible sets to the left side tray, the
senate compared to the thing as well as the is spatial aluminum pot to
set to the right side tray.
Fifth, bad heating curve analysis
1. extracts the high polymer by the heating curve Tig,
Tmg, Teg.
2. compares two kind of polymers the differences. Reference
1. Liu Zhenhai Analytical chemistry handbook
second edition eighth fascicle thermal analysis Beijing:
Chemical industry publishing house, 2000, 64
2. Ni Shaoru Applied chemistry 1989, 6
(2):15
3. Gordon M. J Appl Chem. 1952, 2:493
Nanjing greatly unfolds the mechanical and electrical
technical research institute specialized production differential
thermal analysis meter (DZ3320A), 差示 scanning calorimetry meter
(DZ3335)
Purchase relation: Zhou Yiguang 13.851485841
billion zyg_awp@56.com
| 