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- Dec 21, 2017 -

Tumble Viscometer

This viscometer, as its name implies, is a flat-bottomed cylinder with a cylinder in the center of the shaft. Between the cylinder and the slit there are two slits formed by mutually parallel surfaces in which the polymer liquid is located. Through the stepless speed regulator to make the cylinder for rotational movement. The cylinder is suspended from a force measuring device and connected to it by a spring. As the cylinder rotates, the polymer liquid in the slits flow due to the shearing action, because the body fluid is viscous to drive the cylinder to rotate until the torque of the cylinder equilibrates with the spring force and stops, at which point the circle The barrel rotates a certain angle θ. At equilibrium, the shearing action of the liquid reaches a steady state. Through the torque of the cylinder and the rotational speed of the cylinder, the shear force and the shear rate at each position in the annular gap can be calculated by the formula.


Vertebral - plate viscometer

Vertebral plate viscometer consists of an upper cone and a lower part of the disk, the center of the cone and the disk are in the same axis, the top of the cone is in contact with the original plate, the cone and the disk are rotatable Part of the drum viscometer slightly different is that the polymer melt in the cone and the angle between the disc formed by the slit θ, the rotation of the disc, due to the viscosity of the liquid, will drive the cone rotation in the Under shear equilibrium, the cone stops rotating after turning a certain angle.


Falling ball viscometer

Drop-ball viscometer is also a method of measuring the viscosity of polymers, but it is rarely used to determine the viscosity of the melt. The limitation is that it is not easy to get basic data such as shear force and shear rate. During the movement of the ball, the value of each part of the liquid is not uniform and the data processing is also difficult. Therefore, it is difficult to do a comprehensive analysis for non-Newtonian fluids and only for Newtonian fluids. The maximum shear rate near the sphere can be estimated as 3v / 2R (v is the velocity at which the ball descends and R is the radius of the sphere). The shear rate in the body fluid at the time of measurement is usually below 0.01 per second and the polymer melt at this rate is generally considered to be a Newtonian liquid.

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