ARES rheometers

Dynamic torsional shear experiments were conducted on a Rheometric Scientific ARES rheometer. The samples were cut 6.35 cm in length strips, 0.30 cm thick. The single frequency temperature ramp test was taken at 1 Hz from -100°C to 150°C at 2°C/min in the linear strain regime (0.01 to 2.00%). 

Table 17.11 shows data for neat and a rice-hulls-fllled HDPE in the steady shear flow (a cone die) and the dynamic shear. One can see that the difference in the consistency index for neat HDPE between these two experimental approaches was only 14%. However, that for the filled composite was 32%. In the presence of the coupling agent, the difference was much higher 116,400 Pa.s" (cone die) and 50,600 Pa.s" (ARES rheometer), that is, 130% difference. 

Fig. 31. The ARES rheometer was used for rheological investigations (geometry of the measuring device conus-plate diameter d=25 mm angle a=0.1 rad)...

TA Instruments ARES rheometers measure controlled strain and controlled stress by using two technologies combined motor and transducer (CMT) and separate motor and transducer (SMT). The company s rheometer instrument controls using Ochestrator software include... 

The mechanical properties of frozen materials can be difficult to study due to the enormous stiffness and moduli involved and the fact that changes can occur rapidly over small temperature ranges. The Ares rheometer (Rheometrics Corporation/TA Instrument, Delaware, USA) has a wide range of modulus measuring capability and has been used in the oscillating plate mode in studies of sugars at comparatively low moisture contents (15% —10°C) with and without hydrocolloids [141]. 

Effects of instrument compliance can induce large errors on shear measurements of elastic and viscoelastic properties of materials [1,2]. These effects are caused not only by the transducer but also the machine itself (load frame), and the rheometer fixtures. We present examples of rheometer compliance effects on the measurement of the material properties of small molecule glass formers and a commercially available polydimethysiloxane (PDMS) rubber. A TA Instruments ARES Rheometer was used with a strain gage transducer (Honeywell-Sensotec). Stress relaxation, aging experiments, and dynamic frequency sweep experiments were performed. We also propose a procedure to correct for comphance effects in stress relaxation experiments and dynamic frequency sweep experiments. Suggestions are made for both instrument and experimental design to avoid and/or reduce compliance effects. 

Three HIPS resins possessing distinct rheological properties were utilized in this study STYRON 1200, 1170, and 484. These resins have melt flow rates (MFR) of 5.0, 2.1, and 2.8 g/10 min (200T05kg) and will be referred to in the paper as HIPS 1, HIPS 2, and HIPS 3, respectively. The dynamic mechanical spectroscopy measurements (viscosity vs. frequency and temperature, loss and storage modulus vs. frequency and temperature) were performed on a TA Instruments ARES rheometer. The measurements were obtained at three different temperatures 170, 190, 210, and 2301C. The uniaxial extensional viscosity measurements were performed at three Hencky rates 0.1, and 10s on a SER (Sentmanat Extensional Rheometer, Xpansion Instruments) at 1701C. 

Extensional viscosity was measured at 170°C on a Sentmanat Extensional Rheometer (SER) fixture (Xpansion Instruments).[1] The SER is based on a dual drum system. It is designed as a fixture of a standard rotational rheometer which consists of a master and slave wind-up dmms coupled via intermeshing gears. A constant Hencky strain rate is obtained simply by setting a constant winding speed. The SER fits inside the environmental chamber of an Advanced Rheometric Expansion System (ARES) rheometer. Tests were carried out on strips cut out of a 0.5 mm thick compression molded sheet. Constant Hencky strain rates (1 and 10 s ) were applied and the time-dependent stress was determined from the measured torque and the sample time-dependent cross-section. The extensional viscosity, tie, was obtained by dividing the stress by the Hencky strain rate. 

In this study, two optical grade polycarbonates, Lexan OQ1030 and OQ3820 from General Electric Company, have been used to obtain master curves on both relaxation modulus and the strain-optical coefficient (for details see Ref. [8]). The complex viscosities as a function of frequency at various temperatures were obtained by ARES rheometer. The fitted and experimental data are shown in Fig. 1. 

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