![]() ![]() ![]() The shear rate can be adjusted even by changing the frequency of vibration, but the vibrating tuning-fork type device increases sensitivity through sharp resonance phenomena and is inviting a reduction of sensitivity if the oscillation frequency is changed. With the rheometer developed from the vibration viscometer with adjustable shear rate, the shear rate is varied by changing the amplitude of the oscillating sensor plates. Liquids with low viscosity can often be displaced by the centrifugal force from rotations and problems with repeatability can also occur with rotary rheometers. On the other hand, a lot of energy is required to rotate the rheometer and the state of the sample may be altered from that of before rotation, skewing the measurement. The main features of rotary-type rheometers are a great level of control over the variation width of the shear rate by changing the rotation frequency, and being able to apply the shear rate uniformly to the sample through configuration of the rotor. Presently, almost all rheometers are rotary type devices. In response, we did not change the natural frequency of the 30Hz oscillators, but instead set about changing the oscillation amplitude by developing a new rheometer: our new RV-10000 model. When our viscometer was first released for sale eight years ago, we received many requests from customers who wanted to know the value of the "shear rate", or be able to adjust it in their measurements. As I have previously written about tuning-fork vibration viscometers, they were incorporated two years ago as one of the standards in measuring viscosity in the first such revision to Japanese industrial standards in 19 years (JISZ8803), and have also already been accredited as a viscometer subject to calibration by the Japan Calibration Service System (JCSS). Our tuning-fork vibration rheometer was first introduced to the market in September this year at the Japan Analytical Scientific Instruments Show (JASIS) 2012. ![]()
0 Comments
Leave a Reply. |