How to measure the viscosity of adhesive?
Adhesive is a high-viscosity liquid with non-Newtonian flow properties. Generally, a Rotational Viscometer is used to measure the stress required to reach a fixed shear rate and convert it into viscosity. It is generally not recommended to use a Viscosity Cup for testing, and the Viscosity Cup is more suitable for the determination of low viscosity values.
This experiment uses the NDJ-1 Rotational Viscometer, which is a very common viscosity instrument in rheology research. There are many types of Rotational Viscometers, including digital display type, pointer type, etc. (as shown in the figure below). In addition, a thermometer with a division of 0.1°C is used.
Desktop digital Rotational Viscometer |
Pointer Rotational Viscometer |
Portable digital Rotational Viscometer |
specific operation
According to the viscosity of the adhesive sample, select the appropriate rotor and rotating speed so that the reading is within the range of 20% to 80% of the dial, balance the sample temperature with the test temperature, and keep the sample temperature uniform. Then immerse the rotor vertically into the center of the sample, and make the liquid level reach the rotor liquid level mark, and start the Rotational Viscometer. Read the value when the pointer stays on the disc while rotating.
The result shows
Repeat the measurement for each sample three times, take the smallest value among the three sample tests as the test result, and take three significant figures.
Precautions
1) Be careful when loading and unloading the rotor, and do not use too much force to prevent the rotor from bending. Do not place the instrument on its side or upside down with the rotor installed.
2) The connecting section and thread of the connecting screw and rotor should be kept clean, and the rotor should be cleaned in time after each use and properly placed in the rotor frame.
This article takes the NDJ-1 pointer rotary viscometer as an example to introduce the viscosity measurement method of adhesives. Of course, other types of rotary viscometers can also be used for testing. The specific operation method is tested according to the function settings and operating instructions of the actual rotary viscometer. .
