Advanced Rheometric Expansion System (ARES)
The ARES originally had a 2K FRT (Force Rebalanced Transducer) installed in the system. The 2K FRT gives a very good response for low torque application, but has a limited range (torque 2000 g-cm, normal force 2000 g). It has also been observed that there are problems measuring normal force using the 2K FRT because of its "active" nature.1,2 The active nature causes the transducer shaft to heat up and expand, thus giving erroneous results for normal force measurements.1,2 The modification to the ARES system is the addition of a custom designed strain gauge transducer built by Sensotec that is more robust than the FRT (torque 20,000 g-cm, normal force 5000 g) and gives results that are more accurate for normal force.3
- J. M. Niemiec, J. J. Pesce, G. B. McKenna, S. Skocypec and R. F. Garritano, J. Rheology, 40, 323-334, (1996).
- C. R. Schultheisz and G. B. McKenna, ANTEC 1999, Proc. 58th. Annual Technical Conference, Society of Plastics Engineers (1999).
- S. A. Hutcheson, X. Shi and G. B. McKenna, ANTEC 2004, Proc. 62nd. Annual Technical Conference, Society of Plastics Engineers, Vol. L, pp. 2272-2276 (2004).
- Supplied with 2KFRT (Force rebalanced transducer).
- Strain controlled
U.S. Patent 4,601,195, Apparatus and Method for Measuring Viscoelastic Properties of Materials, 1986.
- The 2KFRT is an "active" transducer servo-controlled motor drives system back to its zero position after a displacement is sensed (capacitance sensors)
- Torque range
- (Hi) 200-2000 g-cm
- (Low) 0.02-200 g-cm
- Stability: 0.002% of full range when thermally equilibrated (±0.04 g-cm)
- Normal force range: 2-2000 g
- Stability: 0.01% of full range when thermally equilibrated (±0.2 g)
Strain Gauge Transducer
- Sensotec Model 060-G42001 Semiconductor strain gage based technology
- Torque range: up to 20,000 g-cm
- Stability: 0.1% of full range (±20 g-cm)
- Normal force range: up to 5000 g
- Stability: 0.1% of full range (±5 g)
- Operating temperature: -23 °C to 93 °C
- X. Shi and G. B. McKenna, "Mechanical Hole Burning Spectroscopy: Evidence for Heterogeneous Dynamics in Polymer Systems", Phys. Rev. Lett., Accepted (2005).
- Mandanici, X. Shi, G. B. McKenna and M. Cutroni, "Slow Dynamics of Supercooled m-toluidine Investigated by Mechanical Spectroscopy", J. Chem. Phys. , Accepted (2005).
AR-G2 Stress Controlled Rheometric System
The ARG2 is a commercialized stress controlled rheometer with magnetic bearing, which may provide a higher sensitivity to small torque change than common air bearing rheometers. The steady torque is reported to be as low as 0.01 µN-m. The ARG2 in our lab is equipped with an Environmental Test Chamber (ETC) with temperature range from -160 to 600 °C and the optional Electrically Heated Plate (EHP) system provide a narrow temperature range (-70 to 400 °C). The device is equipped with standard 25 mm, 40 mm and self-made disposable 8 mm parallel plate and 25 mm , 40 mm cone plate, which can be used to do most of the conventional rheological test such as frequency sweep, amplitude sweep, temperature sweep, stress relaxation, creep/recovery, normal force measurement.