Digital rotational viscometer is used to measure the viscosity resistance of liquids and liquids, and is widely used to determine the viscosity of various fluids such as grease, paint, plastic, food, medicine, cosmetics, adhesive products and so on.
With the development of science and the improvement of industrial production, measuring the viscosity of substances has become very important, and can be used to determine the viscosity and flow behavior of polymer liquids. Because most polymers are processed and formed under viscous flow conditions, for the determination of polymer viscosity, the mastered performance rules are very important in the polymer production process.
The existing viscosity meter mainly has several types of drum type, cone plate type and parallel plate.
History of rotational viscometer
The rotational viscosity measurement method pioneered by the American family uses the unique relationship between the shear and resistance between the rotor and the fluid to create a new measurement of viscosity. The Brookfield family has designed the world's first dynamic viscosity measuring instrument under the name of their own family, which is the rotational viscosity measuring instrument, which is today. And Brinell is also the abbreviation of the Brookfield family name.
From the beginning of the dial type, after 75 years of transformation and upgrading, its performance is getting better and better. Afterwards, DV-I, DV-II, and DV-III, which have gradually appeared, have created great progress in viscosity measurement. This makes viscosity measurement not only a simple measurement of viscosity, but also other fluid properties, such as thixotropy.
Later, the rotary viscometer entered the Chinese market and played a great role in the development of my country's polymer industry.
As the name implies, the outside is a flat-bottomed cylinder with a cylinder in the center of the axis. Between the cylinder and the slit there are two slits formed by mutually parallel surfaces, and the polymer liquid is located in this slit. Drive the stepless speed governor to make the cylinder rotate. The cylinder is suspended on a force measuring device and connected to it by a spring. When the cylinder rotates, the polymer liquid in the slit flows due to the shearing action, because the body fluid exists to drive the cylinder to rotate, until the cylinder torque and spring force stop the rotation, then the cylinder rotates a certain amount Angle θ. When in equilibrium, the shearing action of the liquid also reaches a stable state, and then the torque at the cylinder and the rotation speed of the cylinder can be used to calculate the sum of the various positions in the ring seam.
Vertebral plate viscometer
The vertebral plate is composed of an upper part and a lower part of the circular plate, and the center of the circular plate is on the same axis, the top of the cone wants to contact the original plate, the cone and the circular plate are both rotatable parts, and rotating The difference of the barrel viscometer is that the polymer melt is located in the slit formed by the cone and the circular plate at an angle of θ. Rotating the circular plate will drive the cone to rotate due to the liquid. Under the condition of shear equilibrium, the cone Stop rotating after turning a certain angle.
Falling ball viscometer
The falling ball method is also a method for measuring the viscosity of polymers, but it is rarely used to measure the viscosity of the melt. Its limitation is that it is not easy to obtain basic data such as sum. During the movement of the ball, the values of Υ in each part of the liquid are not uniform, and data processing is also difficult. Therefore, it is difficult to make a comprehensive analysis, which is only applicable to the maximum shear rate in the vicinity of the ball, which can be estimated as 3v/2R (v is the falling speed of the ball. R is the radius of the ball). The shear rate in body fluids during measurement is usually below 0.01 per second, polymer melts are generally considered to be liquids at such rates.