Viscoelastometer, Rheovibron

A variety of commercial instruments are available for the determination of the viscoelastic behavior of samples. Figure 3.15 shows one such apparatus, the Rheovibron Viscoelastometer. This instrument also takes advantage of the complementarity that exists between time and temperature It operates at four frequencies over a 175°C temperature range. With accessories, both the frequency range and the temperature range can be broadened still further. 

Figure 3.15 The Rheovibron Viscoelastometer, a commercially available instrument for the determination of the dynamic moduli and compliances. [Photo courtesy of Imass, Inc, Accord (Hingham), Mass. 02018.]...

A Toyo Boldwin Rheovibron Viscoelastometer Rheo 2000/3000 machine was used for these determinations. Such measurements were performed at a frequency of 110 Hz, a heating rate of 2°C/min and an inter-chuck distance of 40mm. 

Dynamic Mechanical Testing - Film properties such as impact resistance and the cure response of thermosetting resins are conveniently investigated by dynamic measurements in which an oscillatory or torsional strain is applied to the sample with the stress and phase difference between the applied strain and measured stress being determined. In the present study, a Rheovibron Viscoelastometer was used which employed a sinusoidal strain at a... 

The acoustical properties for all samples were evaluated by using either a Toyo DDV-II Rheovibron viscoelastometer at 110 Hz, or a string apparatus developed at NRL-USRD, (8). In this latter instrument, dynamic Young s moduli and loss tangent were measured in the frequency range of 1-10 kHz, and master curves were obtained by using the time-temperature superposition technique, (9). 

Poly-2,5(6) benzimidazole Methane sulfonic acid, HCOOH/cresol Solvent nature affects the morphologies of polymer films thus the extensibility and mechanical properties of films. DSC, Rheovibron viscoelastometer, WAXS [Wereta et at, 1978]... 

FIGURE 3, Viscoelastic Spectrum of KYHAR PVDF (Rheovibron Viscoelastometer... 

Absolute values of shear modulus cannot be determined via TBA however, it is quite useful to follow the dynamic mechanical properties of reactive systems (e.g., epoxy curing) [21]. Forced vibration, almost exclusively employed today, fixes both ends of a sample and applies a sinusoidal tensile or shear strain, which yields sinusoidal stress response with a phase angle S lag. As with free vibration, Eqs. 5.13 to 5.16 apply. Typical instruments employed include Rheovibron viscoelastometer and various versions of dynamic mechanical analyzers. For forced vibration, the frequency range of 0.01 to 100 Hz is commonly available with a temperature range of —150 °C to >400°C. A discussion of the details and utility of dynamic mechanical analysis can be found in [19, 22]. The stress-strain response of forced vibration and free vibration is illustrated in Fig. 5.3. 

Characterization Methods. Stress-strain experiments were carried out with an Instron model 1122. Dogbone samples of 10mm in length were used, and the initial strain rate was 2 mm/min. Dynamic mechanical data were obtained utilizing a DDV-IIC Rheovibron Dynamic Viscoelastometer. Most samples were tested within the temperature range of -100°C to 220°C with a heating rate of 2-3°C/min. A frequency of 11 Hz was selected for all the dynamic mechanical experiments. 

Molecular mixing via dynamic mechanical spectroscopy. While electron microscopy yields the phase size, shape, etc., as delineated above, dynamic mechanical spectroscopy (DMS) yields the composition within each phase. The DMS measurements employed a Rheovibron direct reading viscoelastometer model DDV-II (manufactured by Toyo Measuring Instruments Co., Ltd., Tokyo, Japan). The measurements were taken over a temperature range from -120°C to 140°C using a frequency of 110 Hz and a heating rate of about 1°C/ min. Sample dimensions were about 0.03 x 0.15 x 2 cms. 

Bulk samples were sectioned with a diamond saw to provide samples for the Rheovibron DDV II Viscoelastometer operated at 11 Hz. In some cases a thin sheet cured between aluminum plates, was heated to the rubbery state, cut while hot, then returned to the oven to complete the cure. 

The isothermal DSA analysis, utilizing the Rheovibron DDV-IIB dynamic viscoelastometer, has been described elsewhere (7). A steel spring 2.9 mm in outer diameter of 0.30 mm diameter wire, seventeen turns in length was placed in the Rheovibron. The temperature chamber was then brought to constant cure temperature,... 

The buffering action of a coating in this situation is determined by the relaxation modulus of the coating material. The relaxation modulus may be measured on a film cast from the material by carrying out tensile-stress relaxation measurements with a suitable apparatus such as a Rheovibron dynamic viscoelastometer operated in a static mode. Figure 13 (inset) displays such measurements for the four coating materials used on the fibers measured in Figure 12. The measurements were carried out at 23 °C at small tensile strains, where the materials exhibit linear viscoelastic behavior. 

SBR CHX, Toluene, Et-acetate, Tetralin, Cyclohexanone Eilm properties depended on the evaporation rate, but there was no evaporation rate dependence when the casting solvent was CHX. Density measurements, Rheovibron dynamic viscoelastometer, TMA, SEM [Beamish and Hourston, 1976 Beamish et al. 1977]... 

Physical Property Evaluation. A Rheovibron (direct reading dynamic viscoelastometer, model RHEO-200, manufactured by Toyo Measuring Instruments Co.) was used to measure the temperature dependence of the complex modulus and damping, tan 6, at 11 Hz. 

Toyo-Baldwin Rheovibron DDV-II-EA dynamic viscoelastometer frequency 3.5 Hz heating rate 3.0 °C min sample size 30.0 x 4.0 x 0.3 mm. 

The mechanical measurements were carried out on a Rheovibron Dynamic Viscoelastometer, Model DDVII. The frequencies employed were 3.5 H, 11 H, and 110 H and the temperature range was from -100°C. to +T70°C. depending on the Tg of the polymer under observation. Tan 6, E and E" were obtained at the quoted frequencies as functions of temperature by standard techniques. 

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