Spectrometer mechanical

The Imass Dynastat (283) is a mechanical spectrometer noted for its rapid response, stable electronics, and exact control over long periods of time. It is capable of making both transient experiments (creep and stress relaxation) and dynamic frequency sweeps with specimen geometries that include tension-compression, three-point flexure, and sandwich shear. The frequency range is 0.01—100 H2 (0.1—200 H2 optional), the temperature range is —150 to 250°C (extendable to 380°C), and the modulus range is 10" —10 Pa. 

Spccj/jfc Fluids Viscoela.stometers, The ATS RheoSystems Stresstech rheometer can carry out oscillatory measurements over a frequency range of 6.3 x 10 to 630 rad/s. The Bohlin VOR rheometer and the mechanical spectrometer both allow oscillatory measurements. The former has a frequency range of -10 Hz, the latter lO " -100 Hz. The maximum angular ampHtude is 0.02 rad for the VOR and 0.5 rad for the mechanical spectrometer. 

Rheometric Scientific markets several devices designed for characterizing viscoelastic fluids. These instmments measure the response of a Hquid to sinusoidal oscillatory motion to determine dynamic viscosity as well as storage and loss moduH. The Rheometric Scientific line includes a fluids spectrometer (RFS-II), a dynamic spectrometer (RDS-7700 series II), and a mechanical spectrometer (RMS-800). The fluids spectrometer is designed for fairly low viscosity materials. The dynamic spectrometer can be used to test soHds, melts, and Hquids at frequencies from 10 to 500 rad/s and as a function of strain ampHtude and temperature. It is a stripped down version of the extremely versatile mechanical spectrometer, which is both a dynamic viscometer and a dynamic mechanical testing device. The RMS-800 can carry out measurements under rotational shear, oscillatory shear, torsional motion, and tension compression, as well as normal stress measurements. Step strain, creep, and creep recovery modes are also available. It is used on a wide range of materials, including adhesives, pastes, mbber, and plastics. 

Striking support of this contention is found in recent data of Castro (16) shown in Figure 14. In this experiment, the polymerization (60-156) has been carried out in a cone-and-plate viscometer (Rheometrics Mechanical Spectrometer) and viscosity of the reaction medium monitored continuously as a function of reaction time. As can be seen, the viscosity appears to become infinite at a reaction time corresponding to about 60% conversion. This suggests network formation, but the chemistry precludes non-linear polymerization. Also observed in the same conversion range is very striking transition of the reaction medium from clear to opaque. 

Fig. 17. Flow curve for various concentrations of polystyrene (Mw=2 106g/mol) in decalin solutions at 25 ° C obtained with a low-shear viscometer (A), a mechanical spectrometer ( ) and a high-shear con centric-cylinder viscometer (O)...

The samples were cured with 0.2, 0.4, 0.8 and 1.6 wt.% dicu-myl peroxide. In this way, we obtained twelve different networks with great variations in relaxation Intensities. Dynamic mechanical measurements were performed In torsion in the linear region (deformations smaller than 5 %) with a mechanical spectrometer, using the parallel-plate geometry. The frequency ranged from 0.01 to 15 Hz and the temperature was usually between 300 and 435 K. 

Viscosity measurements were made using a Rheometrics System IV-dynamlc mechanical spectrometer. 

Rheological Properties Measurements. The viscoelastic behavior of the UHMWPE gel-like systems was studied using the Rheometric Mechanical Spectrometer (RMS 705). A cone and plate fixture (radius 1.25 cm cone angle 9.85 x 10" radian) was used for the dynamic frequency sweep, and the steady state shear rate sweep measurements. In order to minimize the error caused by gap thickness change during the temperature sweep, the parallel plates fixture (radius 1.25 cm gap 1.5 mm) was used for the dynamic temperature sweep measurements. 

Dynamic melt viscosity studies on the star blocks and a similar triblock were carried out using a Rheometric Mechanical Spectrometer (RMS) (Rheometrics 800). Circular molded samples with -1.5 mm thickness and 2 cm diameter were subjected to forced sinusoidal oscillations (2% strain) between two parallel plates. The experiment was set in the frequency sweep mode. Data were collected at 180 and 210 °C. 

The dynamic melt viscosity measurements of select star blocks and a similar triblock were carried out on a rheometric mechanical spectrometer, RMS. Circular molded samples of 2 cm diameter and -1.5 mm thickness were subjected to forced sinusoidal oscillations. Dynamic viscosities were recorded in the frequency range of 0.01-100 rad/s at 180 °C. Figure 10 shows the complex viscosities of two select star blocks and a similar linear triblock. The plots showed characteristic behavior of thermoplastic elastomers, i.e., absence of Newtonian behavior even in the low frequency region. The complex viscosity of the star block... 

Example 11.1 Chain Modification (Branching and Partial Cross-linking) of PET with Triglycidyl Isocyannrate (TGIC) Dhavalkikar (39) conducted the reaction cited in the Example title on samples placed between the rheometrics mechanical spectrometer (RMS) parallel disks in the temperature-controlled chamber under nitrogen. He followed the reaction dynamics chemorheologically by measuring, in-line, the in- and out-of-phase dynamic moduli G (t) and G"(t) they are indicative of the elastic and viscous nature of the molten reactive samples. 

Viscoelastic experiments were conducted on a Rheovibron DDV-II-C apparatus and on a Rheometrics Mechanical Spectrometer. The Rheovibron studies were carried out in tension on cured samples at 3.5, 11,... 

All of the evidence presented above supports the conclusion that the diblock copolymers are essentially homogeneous. On the other hand, the corresponding homopolymers have been shown to be incompatible in essentially all proportions under similar conditions of sample preparation. Thus, if at room temperature the BR and IR can be made compatible by the addition of a single chemical bond, i.e., the one linking the two segments in the diblock copolymer, it is not unreasonable to expect that an upper critical-solution temperature for the homopolymers might exist not far above room temperature. The direct determination of this temperature by visual methods (27) was not feasible in the present case because of the nearly equal indices of refraction of BR and IR. As an alternative, the dynamic shear properties of a 50/50 blend of IR and BR were determined in the Mechanical Spectrometer from 30° to 200°C. 

The authors are grateful to Paul Rempp of the Centre de Recherches sur les Macromolecules, Strasbourg, France, for generously supplying the diblock copolymers used in this study. Homopolymers were supplied by Shell Chemical and Phillips Petroleum. Support for this research was provided by the Office of Naval Research and by the Petroleum Research Fund, administered by the American Chemical Society. The Rheometrics Mechanical Spectrometer used in this study was obtained through the support of the RIAS Program of the National Science Foundation. 

Dynamic mechanical measurements were performed with a Rheometrics model RMS 7200 mechanical spectrometer at a fixed frequency of 1 rad/s through a temperature range from -100 C to 150 C under dry nitrogen. The test specimens were prepared in rectangular shape about 60 mm in length, 11 mm in width, and 4 mm in thickness. The applied strain was 1%. 

The Torsion Impregnated Cloth Analysis (TICA) measurements utilized here were conducted under nitrogen with a Rheometrics Mechanical Spectrometer (RMS) according to the procedures described in the previous paper (7). 

The TICA specimen preparation procedure has been described elsewhere (4). The mechanical measurements were made with the Rheometrics Mechanical Spectrometer (RMS) which measures the in-phase and out-of-phase stress response (a and b component respectively) of a specimen being subjected to a sinusoidal shear strain. The instrumental set-up was reported by Lee (6). The frequency of the strain function was kept constant at 1.6 Hz (10 rad/sec). All temperature scan experiments were scanned at 2 C/min rate. The temperature was scanned down at the same rate when the maximum temperature was reached. 

Dynamic viscosity was followed as a function of time at room temperature (23-25 C), 40, 60, 80, and 100 C using 25 mm diameter cone and plate fixtures with 0.1 radian cone angle on a Rheometrlcs Mechanical Spectrometer. The oscillating frequency... 

Rheometrics Mechanical Spectrometer Operating Manual, Rheometrics Inc., 1974. 

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