Viscosity index improver is an important additive mainly used to adjust and improve the viscosity index of liquids or gases. In rheology, the viscosity index is used to measure the fluidity of a substance under shear. The higher the viscosity index, the less fluid the material is under shear, and vice versa.
Viscosity index improvers, also known as viscosity modifiers or viscosity index improving additives, are additives added to lubricating oils to enhance their viscosity-temperature relationship. These additives help reduce the effects of temperature changes on the oil’s viscosity, making it more stable and suitable for use under a wide range of operating conditions.
An oil’s viscosity index is a measure of how its viscosity changes with temperature. Oils with a low viscosity index tend to become too thin at higher temperatures and too thick at lower temperatures, which can negatively affect their lubricating properties. On the other hand, oils with a high viscosity index maintain their viscosity more consistently across temperature ranges.
Viscosity index improvers work by changing the oil’s viscosity-temperature relationship. At low temperatures, these additives help increase the viscosity of the oil, preventing it from becoming too thick and ensuring good flowability. At high temperatures, they help reduce viscosity, prevent over-dilution of the oil and maintain a proper lubricating film.
Viscosity index improvers are typically high molecular weight polymers dissolved or dispersed in lubricating oils. These polymers have the ability to expand or uncoil in response to changes in temperature, thereby changing the flow behavior and viscosity of the oil.
By increasing the viscosity index, these additives help improve the overall stability and performance of the lubricant. They help the oil maintain the required viscosity and lubrication properties over a wider operating temperature range, ensuring effective lubrication and protection of engine components.
Looking to the future, the development direction of viscosity index improvers mainly has two aspects: first, continue to conduct in-depth research and development of new viscosity index improvers to meet the needs of different fields and different products; second, explore the combination of viscosity index improvers and other additives synergy to improve the overall performance and benefits of the product.