![]() The term high viscosity should not be used as a descriptor of cement that reaches dough phase more quickly, but rather cement that has a higher viscosity at its dough phase when it is typically applied.Īseptic loosening biomaterials cement penetration cement viscosity radiolucent lines total knee arthroplasty.Ĭopyright © 2021 Elsevier Inc. How can we tell the difference between high viscosity and low viscosity liquids A material’s viscosity is a measure of its resistance to flow. ![]() A lower viscosity fluid with a high viscosity index may be required. These findings suggest that the marketing description of HVC or LVC is not necessarily a factor in cement penetration. Cavitation, High viscosity at the pump inlet can cause cavitation wear. There were fewer tibial radiolucencies with HVC than LVC. There was no significant difference in maximum penetration in any zone between the two cements. Mean maximum cement penetration in 3 of the 4 zones was >3 mm with both cements. Materials that are low viscosity flow thin and quick, while high viscosity materials flow. For example, a substance with a thick viscosity resists movement while a low viscosity substance moves quickly. In addition to measuring thickness, viscosity measures resistance to motion. An example of a high viscosity liquid is syrup. There were no cases of aseptic loosening in either cohort at a mean of 29 months. The same terminology applies in different plastic injection materials. Low viscosity refers to substances that are thin, such as water, while high viscosity substances are thick. Depth of cement penetration and presence of RLL were measured in four tibial zones and were compared between cohorts. The HVC (n = 50) and LVC cohorts (n = 50) were gathered from two sequential series of primary total knee arthroplasties using the same implants and cementing techniques. We hypothesized that no significant difference would be found in depth of penetration or presence of RLLs between the two cohorts. ![]() TURBULENT FLOW When a turbine-type mixer creates turbulence in the lower viscosity ranges (less than 5,000 centipoise), the resulting flow is chaotic. We compared cement marketed as high-viscosity cement (HVC) with one marketed by the same manufacturer as low-viscosity cement (LVC). To better understand the ramifications of high-viscosity mixing, let’s first review a much simpler case that of turbulent flow in low-viscosity mixing. JavaScript is currently disabled.Please enable it for a better experience of Jumi.Previous studies have shown that the depth of cement penetration and the presence of radiolucent lines (RLLs) correspond with the risk of aseptic loosening in total knee arthroplasty, while others have found a correlation between the viscosity of the cement and the depth of cement penetration. There is no direct connection between the adhesive base and the flow behaviour when heated. Hot-melt adhesives have values between 100 mPas and over 15.000 mPas and are selected for the corresponding application. Here are some examples of viscosity values: In general, every substance – including solids – has a viscosity, but this is so high that flow behaviour is usually not recognisable.Ī typical example is glass, which, given the right load and time, can also be penetrated by another solid without being damaged. For this reason, viscosity is specified at a certain processing temperature. The following applies to hot-melt adhesives: The higher the melting temperature, the thinner/ lower the viscosity and vice-versa. The higher the viscosity, the more viscous the substance. Today, HTHS viscosityor specifically low HTHS viscosityis a phrase fast becoming associated with increased fuel efficiency. The dynamic viscosity is expressed in mPas or micro-Pascal seconds.1 Pa*s corresponds to 1 Ns/m². The particles of high-viscosity fluids are more strongly bound together, making them less mobile than the particles of low-viscosity liquids. However, this is not usually used as a measure for evaluating adhesives. Except at very high pressure, the viscosity of air depends mostly on the temperature. The opposite of viscosity is what is known as fluidity. Under standard atmospheric conditions (25 ☌ and pressure of 1 bar), the dynamic viscosity of air is 18.5 Pa·s, roughly 50 times smaller than the viscosity of water at the same temperature. The plant genus mistletoe has the scientific name “ Viscum”. The term viscosity is derived from bird glue, which used to be made from mistletoe. Viscosity means the fluidity of a substance.
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