Polyolefin and poly(alkyl methacrylate) mixed additives as mineral lubricating oil rheology modifiers

Abstract

Some rheological properties of mineral lubricating oils containing polyolefin (OCP) (ethylene/propylene copolymer) and poly(alkyl methacrylate) (PAMA) mixed additives over a wide composition range have been examined. Increasing the OCP content significantly increases the viscosity and shear stability of solutions, whereas the viscosity index is directly proportional to the PAMA content. The pour point values of the additive solutions investigated are lower than −30°C even for the smallest concentration of PAMA in the polymer mixture of 15 wt.% (at a total polymer mixture concentration in oil of 2 wt.%). The viscosities of dilute mixed additive solutions obey the typical Krigbaum‐Wall equation and, due to the negative viscometric interaction parameter values (Δb12 < 0), the OCP/PAMA mixture is found to be immiscible. The immiscibility becomes more pronounced on increasing the overall polymer concentrations. The viscosities of concentrated mixed additive solutions decrease significantly with an increase of OCP content, showing a minimum of half the initial value at a polymer ratio of about 50/50. On decreasing the polymer concentration to practical levels as well as increasing the temperature, the viscosity values approach the ideal additivity law. Based on the ratio of specific viscosities at 40 and 100°C (Q), the OCP additive solution shows a better thickening effect at lower temperatures (Q < 1). On the other hand, the PAMA additive solution shows a better effect at higher temperatures (Q > 1) with more coherent thickening with temperature change. The mixed polymer additive, containing ∼10 wt.% OCP and ∼90 wt.% PAMA, is a nearly optimal viscosity‐index improver showing the same thickening effect at different temperatures. The results obtained are promising as regards the design of lubricant formulations with mixed polymeric additives.

Alkyl methacrylate and styrene terpolymers as lubricating oil viscosity index improvers

“…The high values of SSI are the consequence of high terpolymer M w values, which is the adjustable parameter in a polymerization process. However, an adequate composition and ratio of long-chained alkyl groups, consistent with the composition of the base oil paraffinic hydrocarbons, assures the optimal low-temperature properties of lubricating oil [7], Besides these parameters, the lubricating properties may also be characterized by the Q factor [8], which is the ratio of the normalized viscosity values at two different temperatures, usually 40 and 100ºC:…”

Thermal properties and side chain crystallinity of styrene and n‐alkyl methacrylate terpolymers

“…Hence, the 0.05 wt% solution of MMA/DDMA/ODMA copolymer in mineral base oil decreases its pour point from about −15°C to below −30°C (Fig. ) . Schematic representation of the effect of polymeric additive on the lowering of the pour point of mineral base oils can be seen in Fig.…”

Obtaining of polymethacrylate additives and studying of operational properties of an alloyed industrial oil

“…There are additives with various chemical compositions on the market: polyolefins [7], poly(alkyl methacrylates) [8][9][10], copolymers of hydrogenated styrene-butadiene [11], terpolymers [12], etc. Each chemical composition of the polymer provides a balance between cost and performance characteristics that make them more or less suitable for using in certain compounds of lubricating oils.…”