The Development Of Non-Newtonian Fluid Viscosity Metrology

According to the measurement object,viscosity measurement can be divided into Newtonian fluid metrology and Non-Newtonian fluid metrology.At present,the Newtonian fluid metrology has been well resolved and many countries have established a corresponding value transfer and traceability system.Viscosity measurement process of Non-Newtonian fluid is more complex.The system stability Non-Newtonian fluid is poor.Thus,an effective and reliable international metrology standard system of Non-Newtonian fluid has not established.A number of advanced industrial countries,such as the United States,Germany and Japan,have conducted research on the device of non-Newtonian fluid viscosity and the development of relevant reference materials,but no reference material has been included in the International Standard Substance(COMAR).Non-Newtonian fluid viscosity measurement methods include capillary and rotational method.Capillary method is off-line measurement and only measure linear low viscosity samples.Rotational method is an internationally accepted non-Newtonian fluid standard method and has been used in non-Newtonian fluid metrology studies in Germany and Japan.However,Rotational method is often not used as the primary standard in viscosity metrology system,because of the relatively poor accuracy and repeatability of this method.So improving the accuracy of viscosity measurement has become the focus of the field of viscosity research.In this paper,the stress-controlled rotational rheometer in the rotational method is used to measure viscosity of non-Newtonian fluid.The topic is from the "Non-Newtonian fluid metrology technology research" supported by the Ministry of Science and Technology.The objective of this support project is to establish a non-Newtonian fluid metrology standard and to develop a series of non-Newtonian fluid viscosity reference materials.The work of this thesis is to study and establish the non-Newtonian fluid metrology standard method.The method is used to test the viscosity of different non-Newtonian fluids in order to find and determine the stable non-Newtonian fluid reference material candidates.The main contents are as follows:1.Study and establish non-Newtonian fluid metrology methods:(A)the shear rate of instrument itself is calibrated so that the error between nominal value of rotational speed and the measured value is 0-1%to ensure the accuracy of the viscosity measurement;(B)The influence of the inertia of the instrument system on the viscosity measurement results of different viscosity measurement modes is discussed.The changes of the output torque of the instrument with the measurement time are investigated.When the ladder and constant shear rate modes were used to measure viscosity,the inertia of the instrument system had little effect on the viscosity measurement results.When the continuous varying shear rate mode is used,the inertia of the instrument system has a great influence on the viscosity measurement results;(C)The effects of different measurement conditions(such as clamp apparatuses,environmental temperature or bath temperature,equilibrium time and sampling volume)on viscosity measurement were investigated;2.On the basis of the above research,the PEO/SiO2 aqueous solution and the polyisobutylene/benzene oil-based system can be used as non-Newtonian fluid viscosity measurement reference material candidates.Improving the accuracy of viscosity measurement results by calibrating the instrument and determine the viscosity metrology method,the establishment of non-Newtonian fluid viscosity metrology system is of great significance.