The rheological curve thixotropic ring area method is a method to evaluate the thixotropy of a fluid by the area of the closed so-called "thixotropic ring". It is obtained by increasing the rotational speed until reaching a predetermined maximum rotational speed, and then gradually reducing the rotational speed. Put the data points measured by gradually increasing the rotating speed and gradually decreasing the rotating speed in the coordinate system with the shear rate as the ordinate and the shear stress as the abscissa, and then connect the points to get the curve as shown in the figure. A~B~C in the figure are the curves obtained by gradually increasing the speed, and CA is the curve obtained by gradually reducing the speed (approximately a straight line). The closed area formed by these two lines is called the thixotropic area or the thixotropic ring. The larger the area of the ring, the greater the thixotropy of the flow.
Attention should be paid when making the measurement: (1) The measurement of thixotropy not only needs to gradually increase and gradually reduce the speed, but also has a close relationship with the time interval of the measurement. Because the recovery of thixotropy (re-formation of thixotropic structure) increases with time, when increasing and decreasing the speed, their time intervals should be as equal as possible, generally recommended to be 10 minutes; (2) Choose a predetermined The maximum rotational speed is very important, and the area of the thixotropic ring made by different maximum rotational speeds is not the same; ( 3) Although many people who have done thixotropy research think that temperature has little effect on thixotropy, but the determination It is better to carry out under certain temperature conditions. Generally speaking, thixotropy increases when the temperature increases.
The rheological curve thixotropic ring area method (thixotropic ring method for short) is a commonly used and popular method to express the thixotropy of a fluid. In practical applications, the area of the thixotropic ring is generally estimated and compared to determine the thixotropy of different inks. It is rare to calculate the area of the thixotropic ring from the concept of mathematics, because the irregular area The calculation of is very time-consuming.
