In order to examine the mechanical properties of polymers, Alexandrov frequency instruments are now widely used.
In the Aleksandrov apparatus, the phenomenon of relaxation can be examined over a wide range of deformation rates and temperatures. Deformation can be measured by adding a load to the pattern at regular intervals, and the speed of deformation can be measured by the vibration frequency per minute (from 1 to 1000 vibration frequencies).
The pattern is subjected to cyclic deformations of compression and extension, the deformation being a tensile force varying according to a positive law of known amplitude, the frequency of which can be varied by means of a reducer. (Related instrument: Tensile testing machine)
When testing the mechanical properties of paint films and coating films, pressure Sandaroff instruments can also be used effectively when appropriate test methods are ordered. Such an instrument is shown in Figure 141.
The eccentric wheel 1 that rotates at a certain number of revolutions deforms the spring 3 through the slide rod 2. The elastic spring is pressed on the sample 6 placed on the stage 7 through the glass axis 4 and the axis 5. The stage 7 with the wooden block (KofoAKa type) 8 can be moved to the vertical direction by means of the thread 9 screwed into the lower hole of the tube 10. The vessel is contained in a brass cup screwed on a wooden embossed green 2.
The deformation of the sample can be measured by the mirror 13 connected with the pan mirror. Prism is connected in the vise of freeboard 14 and 15. The plate 14 vibrates together with the springs 3 in the perpendicular direction at an amplitude equal to that of the deformation of the sample. At this time, the mirror 13 turns around, and the movement of the light spot reflected by the mirror can be read on the scale.
With this instrument it is possible to plot force and deformation versus frequency over a wide temperature range. Power is supplied by the elastic force of spring 3 and by the eccentricity of eccentric shaft 1. When heating, put an electric stove on the cup 11, and then use a good empty bottle filled with liquid air when cooling.
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