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Technological Background and Latest Market Requirements concerning “Static Viscosity” Measurement with a Tuning-fork Vibration Viscometer

Naoto IZUMO, and Atsushi KOIWAI R&D Division, A&D Company, Limited. Tokyo, Japan

ABSTRACT

We introduce a new method viscometer “Sine Wave Vibro Viscometer” which principle is different from conventional viscometers, such as the capillary viscometers or the rotational one. And also We propose a new viscosity unit “static viscosity[sv] viscosity[Pa·s] density[kg/m
3 ]”. This sine wave vibro viscometer features a small amount of sample and wide range measurements without replacing the sensor. The SV-1A requires only 2ml sample and has measuring range from 0.3mPa·s to 1000mPa·s. The SV-10A requires only 10ml and has measuring range from 0.3m Pa·s to 10000m Pa·s. Also describing the measuring method and features of this vibro viscometer. And explaining about JCSS and the measurement uncertainty evaluation for viscosity. Finally showing the viscosity measurement result of various substances measured with this vibro viscometer. (For example: the cloud point of a surface-active agent, the concentrations for ethanol solutions, the cure process of silicone adhesive and the coagulation process of egg white.) Keywords: Sine Wave Vibro Viscometer, Static Viscosity, JCSS, Uncertainty

1. INTRODUCTION

Various methods have been invented for measuring viscosity. Each of these methods is selected and used in the industry where it is most suitable. However, applications of viscosity measurements are recently expanding into new fields such as measurements of polymeric solutions, adhesive agents, coating materials, abrasives, engine oils, biodiesel fuels, and even soft drinks, cosmetics and human blood. Meanwhile, demands are rising for a measuring system that can minimize the energetic interference to a sample liquid such as rotative force and barycentric shift in order to measure the viscous property that is inherent to the liquid. Moreover, there are increasing requirements for measuring continuously a wide range of viscosities in order to observe a viscosity change caused by a temperature change, the curing of an adhesive agent, etc. The following will present an explanation of the tuning-fork vibration viscometer as a device that satisfies the above requirements, the technical background of its JCSS standardization and actual measurement examples. In addition, the physical quantity measured by the new viscometer, “static viscosity (sv)” [viscosity × density] will be discussed.

2. TUNING-FORK VIBRATION VISCOMETER

In the field of liquid viscosity measurements, the capillary viscometer and the rotational viscometer have a long history and are widely recognized. Meanwhile, although the principle for the vibration viscometer was proposed a long time ago, it was only about 20 years ago that the theory was put into actual practice due to various technological difficulties. The recently developed, tuning-fork vibration viscometer not only realized downsizing and price-reduction of the instrument but also made it possible to perform wide-range, continuous measurements from 0.3 mPas (equivalent of acetone) up to 10,000 mPas. More recently, measurements with as small as 2ml sample liquid have become possible, whose applications including the viscosity measurements of such fluids as resist inks for liquid crystals and human blood. The high-performance, tuning-fork vibration viscometer is rapidly expanding its scope of applications to where viscosity measurements used to be impossible. Meanwhile, due to quality control requirements in offshore manufacturing, the precision and the user-friendliness of the tuning-fork vibration viscometer have also been gaining attention at the production level (although delocalization has been decreasing lately).