![]() ![]() For small and moderate H 0 values with respect to particle anisotropy field H k the SAR of the assembly as a function of the particle diameter passes through a characteristic maximum and then reaches a plateau, whereas for sufficiently large amplitudes, H 0 ~ H k, the SAR increases monotonically as a function of diameter. The measuring liquid decelerates the movement of the rotating cylinder, which can be recorded as a measuring signal with different means.Detailed calculations of the specific absorption rate (SAR) of a dilute assembly of iron oxide nanoparticles with effective uniaxial anisotropy dispersed in a liquid are performed depending on the particle diameters, the alternating (ac) magnetic field amplitude H 0 and the liquid viscosity. Then the inner cylinder is driven by a motor while the outer one stands still. In the case of the rotary viscometer, the measuring liquid is placed in a gap between an inner cylinder and an outer cylinder surrounding it. More complex processes must therefore be used for highly viscous media. However, if liquids are highly viscous, you will not get satisfactory results with a flow cup due to the slow flow behavior. ![]() There are flow cups on the market according to DIN 53211 and more precise flow cups according to the newer DIN ISO 2431. DIN4 cup) indicates the diameter of the nozzle opening. There are various DIN and ISO cups for compliance with standards. This result can be converted into centistokes (cST) using a viscosity conversion disk that matches the cup. The time measurement ends when the liquid no longer flows evenly out of the opening or when it breaks. The time measurement starts when it is pulled out. In the case of immersion cups, the cup is immersed in the liquid and quickly pulled out again. The time measurement starts when the liquid begins to emerge from the lower opening of the cup. The nozzle can then be opened and the time measurement begins. ![]() Then we wipe off the excess liquid in the rim of the cup with a glass plate. The time it takes for the liquid to leave the flow cup is measured.įor the process, the test liquid is poured into the flow cup with the nozzle closed. It is a hollow cylinder usually made of anodized aluminum with a stainless steel outlet nozzle. The flow cup is the fastest way to determine viscosity for low-viscosity liquids. To determine the viscosity of liquids, viscosity meters are used: Flow cup You can go directly to the products here. You can use them to stir low and highly viscous substances, liquid or powder, effortlessly and reliably. Our powerful agitators have an extremely high torque. Of course, these are only approximate values, because the viscosity of some substances can vary from type to type, for example honey: Substance To get a better idea of the abstract, here are a few examples from everyday life. Of course, the viscosity also depends on other factors, such as the specific material properties such as the shape and size of the molecules, etc. It is therefore important to include the temperature when determining the viscosity. When the temperature drops, it rises again. The viscosity decreases with increasing temperature. For example, and most influential, temperature. The viscosity of a substance is also influenced by other factors. The unit centistokes (cST) is also used (see below under flow cups). There is also the unit millipascal second (mPas) for substances with low viscosity. In practice, the unit of measurement pascal second (Pas) has become established. One can now imagine that a substance with a high viscosity is less flowable than a substance with a low viscosity. The condition of substances is divided into low, medium and high viscosity. ![]() How fast or slow the layers move depends on the material properties and determines the viscosity. Electrostatic forces of attraction also act between the smallest particles. This is due to the fact that the particles of the substance stand in each other’s way, so to speak, and “have to pass” each other. The speed naturally decreases from the moving plate to the stationary plate. Now what happens to the layers in between?Įach layer transmits the speed of movement to the next layer differently. The first adjacent layer on the moving plate is dragged along with it, while the layer on the stationary plate stands still. One plate is now pulled in one direction, with forces acting on the layers of the material while the other plate rests. In our imagination, the substance is divided into parallel layers. Between these plates there is a substance that adheres to both plates. Here you take a model that consists of two plates one on top of the other. Viscosity describes the condition of a liquid or gas. ![]()
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