Ethylene-propylene branched copolymers as viscosity modifiers

The present disclosure relates to lubricant compositions comprising branched copolymers and methods of making such compositions. A lubricant composition of the present disclosure includes an oil and a copolymer, and has a high temperature high shear (HTHS) viscosity of about 5 or less, a shear stability index (30 cycles) of about 2% to about 80%, a ratio of thickening efficiency to shear stability index (30 cycles) of about 1: 2 to about 1: 30, a kinematic viscosity at 100 DEG C of about 3 cSt to about 30 cSt, and a thickening efficiency of about 1 or greater. In another embodiment, the present disclosure provides a lubricant composition comprising a first copolymer and a second copolymer, where the first copolymer has a higher ethylene content than the second copolymer, and where at least one of the two copolymers is a long chain branched ethylene copolymer. 本公开涉及包含支化共聚物的润滑剂组合物和制备此类组合物的方法。本公开的润滑剂组合物包含油和共聚物，并且具有约5或更小的高温高剪切(HTHS)粘度、约2％至约80％的剪切稳定性指数(30个循环)、约1:2至约1:30的增稠效率与剪切稳定性指数(30个循环)之比、约3cSt至约30cSt的100℃下运动粘度