![]() ![]() 1 shows the molecular mimic used by Shirota and Castner, together with the viscosity and density values at room temperature and ambient pressure. 6–8 To ensure similarity, the molecular mimic and the corresponding ionic liquid should ideally be isoelectronic and isostructural to each other. The neutral system has been called the ‘molecular mimic’ 6,7 and is a mixture of neutral analogues of the anionic and cationic molecular constituents. In order to optimise the viscosity, it is necessary to develop a mechanistic understanding of the difference between how viscosity arises in ionic liquids and conventional molecular solvents.Ī fair, unbiased comparison between ionic liquids and conventional molecular solvents necessitates two systems which are as similar as possible one charged, and one neutral. This is a key aspect for applications such as batteries, gas separation or biomass processing. 1–5 However, the practical applicability of most ionic liquids is limited by their high viscosity compared with conventional molecular solvents. Introduction In recent years, ionic liquids have transformed from a scientific curiosity to extensively used functional fluids, both in academia and industry. We therefore suggest that the optimisation of the viscosity in room temperature ionic liquids must follow a dual approach. We were thus able to reveal that the relative contributions of coulombic compaction and the charge network interactions are of similar magnitude. We measured the viscosity of the molecular mimic at high pressure to emulate the high densities in ionic liquids, which result from the Coulomb interactions in the latter. To distinguish between these two theories, we compared an ionic liquid with its uncharged, isoelectronic, isostructural molecular mimic. The modelling and prediction of viscosity in ionic liquids is the subject of an ongoing debate involving two competing hypotheses: molecular and local mechanisms versus collective and long-range mechanisms. However, their high viscosity presents a significant challenge to their use changing from niche to ubiquitous. Just as an example, to calculate viscosity index we can use online viscosity index calculator or excel tools.Room temperature ionic liquids are considered to have huge potential for practical applications such as batteries. Common methods for viscosity index calculations are ASTM D2270 and ISO 2909. ![]() Q: How to calculate viscosity index?Ī: The viscosity index of a fluid (usually oil) is calculated from its viscosity at 40 and 100☌. Therefore higher viscosity index or higher VI means fluid is more stable and less changes in viscosity over a wide temperature ranges. Viscosity index indicates the change in fluid viscosity in dependence of temperature. Q: What is viscosity index?Ī: Viscosity index of a fluid is a calculated number according to ASTM D2270 or ISO 2909. For example the viscosity of honey is higher than the water. High viscosity fluid has more resistance to flow than a low viscosity fluid. If viscosity of fluid is high, most likely it is difficult to pour. Hence high viscosity fluids flow less easily or slower. Low viscosity fluids (low resistance to move) flow or pour more easily and faster. Therefore oil/fluids are usually measured at the same temperature to calculate viscosity. Lubricants Viscosity and Viscosity index Q: What is Viscosity?Ī: Viscosity is a fluid’s resistance to flow at given temperature. Press Calculate button to calculate kinematic viscosity (KV) As before, use Clear button to reset and calculate a new viscosity. Calculate Viscosity use calculator 3 to calculate viscosity (KV) Enter known viscosity index (VI) and kinematic viscosity (KV) in table 3. Click Calculate to get KV As previously stated, use Clear button to start a new calculation. Enter kinematic viscosity (KV) in the second row. Similarly with known viscosity index (VI) and viscosity It is possible to calculate viscosity For example enter viscosity index (VI) in the first row of second table. Calculate Viscosity possibility is to calculate kinematic viscosity from viscosity index. Finally, press Clear button to start again. Click Calculate button to get viscosity index (VI). ![]() In the first row table 1, Enter kinematic viscosity (KV) at 40☌, In the same way enter kinematic viscosity in the second row. To calculate viscosity index we need viscosity of an oil both at 40☌ and 100☌. Standard practice for viscosity index (VI) calculation as per ASTM D2270 and ISO 2909. ![]()
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