TA Instruments RSA-G2, Manual

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Dielectric Thermal Analysis
The combination of DETA with a high precision RSA-G2 solids analyzer allows for the
simultaneous collection of rheological and dielectric information. A special set of parallel
plates is connected directly to a dielectric bridge (LCR meter) which imposes a signal at
a certain voltage and frequency/ies. The RSA-G2 also enhances stand-alone dielectric
measurements by improving sample conditions. DETA measurements are conducted on a
material sandwiched between parallel plates, with force applied to ensure good surface
contact. and surrounded by an oven for temperature control. In competitive instruments,
the permittivity, or dielectric constant, is measured by the ratio of capacitance with the
sample in the plates to the capacitance with the same air gap. As temperature changes
and expansion of the plates occurs, the gap changes and the accuracy of the permittivity
suffers. The RSA-G2 FCO (forced convection oven) temperature control. axial force control
with gap temperature compensation capability, and software for interface, results in more
accurate DETA measurements.
DETA Experiments
RSA-G2 DETA SPECIFICATIONS
Geometry
Temperature System
Temperature Range
RSA-G2 to DE Bridge Interface
Available Dielectric Bridges
25 mm Parallel Plates
FCO, Forced Convection Oven
IEEE Internal to Instrument
Keysight Model E4980AL;
20 Hz to 1 MHz; 0.001 to 2 Volts
Keysight Model E4980A;
20 Hz to 2 MHz, 0.005 to 20 V
The RSA-G2 DETA accessory can easily be programmed to run a variety of standard experiments through TRIOS Software. Experiments include dielectric frequency sweeps at isothermal
temperature, isothermal time sweep tests at one or more dielectric frequencies, temperature ramp tests at one or more dielectric frequencies, and temperature step and hold profiles
with single or multiple dielectric frequencies.
Dielectric Frequency Sweep on Rubber
104
f
u..
.310'
to
10'
la'
10' la' 10' 105 106 107
fDE(Hz)
Frequency Sweep
The above figure shows an example of a dielectric frequency sweep run on a rubber
sample under ambient conditions. Shown are the storage and loss permittivity and
loss tangent over a frequency range of 20 Hz to 2 MHz.
Testing Modes and Applications
15
30
15
f
E-
o
-
w
-15
DETA Temperature Ramp on PMMA
25 50 75 100 125 150 175 200
Temperature(' C)
Temperature Ramp
0.175
0.15
0.125
0.1
o
0.075
;,
0.05
0.025
Here is an example of a ramp on a PMMA Sample at four different Dielectric
Frequencies ranging from 1 kHz to 1 MHz. It can be seen here that the magnitude of
E'
decreases with increasing frequency through the transition region and the peak
of the transition in tan
b
moves to higher temperatures with increasing frequency.