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Linseis L75 120LT
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 Features
- 8 measuring
systems operate simultaneously
- temperature range -40°C up to
+160°C
- sample dimensions 4 x 10 x 80mm
- measuring sensor LVDT
- 32 Bit Software running in
Microsoft ® operating environment
Description
The Linseis dilatometer L75/120LT was developed to measure the
expansion of polymer samples. Hereby up to 8 different samples can be measured
simultaneously in a temperature range of –40°C up to +160°C. To cover the
temperature range a commonly available climate chamber is used that incorporates
a cooling generator and a heat source. The measuring sensors are mounted on top
of the heat chamber and connect through a hole into the chamber. The complete
arrangement is airtight, in order to avoid the intrusion of humidity into the
measuring chamber.
It is possible to insert
inert gas into the measuring chamber. The temperature measurement is done by
means of 4 type K thermocouples which are hanging always between 2
samples.
This arrangement enables to get a
good temperature profile over the measuring chamber. The change of the length of
the samples over the temperature change is measured with a LVDT sensor (linear
variable differential transformer). This sensor has a very high resolution of
14nm (Nanometer) 10E-9. All 8 LVDTs are connected to the data acquisition /
controller parts into the connected computer. The normally used polymer samples
can have a length of 80 up to 100mm. The cross-section of the samples can be 4 x
10mm up to 15 x 15mm.
As the used measuring
systems are made out of quartz with an expansion coefficient of approx. 5 x
10E-7/K and is thus very small compared to the normal expansion coefficient of
the polymer samples, the expansion of the measuring system can be
neglected.
For very high accuracy measurements
it is possible to use a calibration standard (none thermal expansion) to
compensate the influence of quartz glass expansion. The maximum measuring range
is +/- 1mm. To measure different sample length (80 up to 100mm) the piston of
the measuring system can be adjusted by a motor.
For the zero adjustment the piston will be adjusted by a threat
made of invar (invar has a very low temperature expansion at RT) that
independent from sample length the core of a transducer (LVDT) is always in the
center (zero adjustment).
For fast and easy
change of samples all piston can be retracted by an excenter (operated by a
motor).
Technical
Data
Linear
measurement range |
+/-1300um(+/-0,5%FS)
+/-1600um(+/-2,0%FS) |
+/-1400(+/-1,0%FS)
+/-1800(+/-10%FS) |
Resolution:
|
+/-0,5%
Full-scale |
max. measurement
error |
+/-1% typical
+/-0,5% Full-scale |
resolution
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100 nm
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measuring
principle |
LVDT
(differential transformer) |
zero adjustment
(by a motor) |
approx. 80 up to
100mm sample length |
load to sample
(adjustable by a spring) |
0 up to 500
mN |
output voltage
amplifier |
+/-1,0V
Full-scale |
sample holder
|
quartz glass
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sample
dimension |
4 x 10 x 80 up
to 100mm |
sample
change |
piston
retraction by an excenter motor operated |
temperature
range |
-40°C up to
+160°C |
power
consumption amplifier |
18VA
maximum |
environment
temperature |
0 up to
40°C |
Software
With the
measurement program “WIN-DIL 8S” it is possible to measure the thermal expansion
of 8 samples parallel. For these two different measurement methods are
available.
Two
point measurement
The two point measurement method will calculate the
average thermal expansion between 2 temperatures values. For this operation the
start temperature of the system will be adjusted after the sample is inserted
and the sample is stabilized. After this the system will be heated to the end
temperature. From the temperature difference and the length change the CTE will
be calculated.
Ak=expansion coefficient in
(10E-4/K)
L0=length at room temperature in mm
Dl=length
change in micrometer at temperature T
Dlref= length change in
micrometer at temperature t ref
T= measurement temperature in
°C
TREF= reference temperature in °C
Continuous
measurement
The continuous measurement method is using the following
principle:
After start of the measurement the start temperature will be
reached and for a stabilization will be waited. After this the system will be
heated to the end temperature with a linear temperature ramp. During this the
length change of the sample and the corresponding temperature will be measured
once per second. The heating rate (K/min) and the sampling rage can be adjusted.
The measurement values for each sample will be stored in a different binary
file. This binary file is compatible to the Linseis standard dilatometer file
format. This means all files can be loaded directly into the WIN-DIL Linseis
evaluation software. The data can be also exported as ASCII files for example to
use it with EXCEL.
File
names and lot numbers
Each sample belongs to a lot number. These lot
number will be also saved in the data file. Due to the reason 8 samples can be
measured parallel, it is possible to combine samples with lots. As file name a
combination of a 7 digit sample ID the separator “X” and the actual number of
the measurement will be used.
During the two point measurement the
extension “DIL” will be added. During the continuous measurement the extension
“IPR” will be added.
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