5.4
TRICOR Systems Inc.
5.3.1 CTU and Slope Determination (Cont'd)
These are provided as part of the hardcopy results. The 225 then calculates the
CTU results as illustrated in Figure 5.3. The slope result is the slope of
Tangent2. Examining Figure 5.3 it is readily seen that a change in the shape of
the temper curve would result in a different CTU and slope result. Therefore, the
combination of CTU and slope results provides a unique numeric representation
of the temper curve. Further, since Tangent1 is determined by the heat of
crystallization process, which begins at a specific temperature for a given
formulation and temper, the original (starting) temperature of the sample is not a
factor in the test results. This is not to say that temperature does not affect
temper. This is to say, for a given temper present in the test sample, the starting
temperature is not a factor in the CTU and slope test results. This is important
since the temperature will vary slightly as part of the tempering process in order
to maintain the desired temper.
Figure 5.3 Temper Curve and Key Parameters Analyzed
T
2
T
1
t
1
t
2
Time
Temperature
T
CTU
SECOND INFLECTION POINT
(= Time/Temperature/Slope
of Tangent2)
Tangent1 - Indicator where heat of
crystallization is first detected.
FIRST INFLECTION POINT
(= Time/Temperature/Slope
of Tangent1)
Intersection of Tangent1 and Tangent2 provides Temperature (T
CTU
) for CTU calculation
CTU = T
CTU
- 63°F + CTU
ADJUST
Tangent2 - Slope is indicator of rate of
crystallization (provided as Slope result
by TMU/TCM)
(RESULT)
(17.2°C)
