What are the advantages and disadvantages of commonly used viscosity index improvers?
Release time:
2022-12-26
Author:
Goncord Oil
The performance of viscosity index improvers directly affects the smoothness of vehicle operation. Currently, the four most common types of viscosity index improvers are polyisobutylene (PIB), polymethyl acrylate (PMA), olefin‑carbon monomer copolymer (OCP), and hydrogenated styrene‑diene copolymer (HSD).
The performance of viscosity index improvers directly affects the smoothness of vehicle operation. Currently, the four most common types of viscosity index improvers are polyisobutylene (PIB), polymethyl acrylate (PMA), olefin‑carbon monomer copolymer (OCP), and hydrogenated styrene‑diene copolymer (HSD).
Polyisobutylene (PIB) was one of the earliest viscosity‑index improvers developed, offering excellent shear stability and thermal‑oxidative stability, though its low‑temperature performance is relatively poor. Poly(methyl acrylate) (PMA) exhibits good low‑temperature properties, thermal‑oxidative stability, and viscosity‑enhancing capabilities, but its shear stability is inferior, making it more suitable for certain industrial lubricants. Ethylene–propylene copolymer (OCP) demonstrates strong viscosity‑increasing ability, shear stability, and thermal‑oxidative stability, and it is currently the most widely used viscosity‑index improver. Hydrogenated styrene–diene copolymer (HSD) boasts outstanding shear stability, viscosity‑enhancing performance, and thermal stability. Both OCP‑type and HSD‑type additives are well suited as viscosity‑index improvers in gasoline engine oils; however, their low‑temperature performance is somewhat limited, so a pour‑point depressant should be incorporated when formulating low‑temperature grades.
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