A comparative study of polymeric additives as biodegradable viscosity boosters for biolubricant formulations

Abstract

Vegetable oils are regarded as renewable energy for future generations due to its biodegradability, high thermal properties, and good lubricity. Some of the disadvantages of vegetable oil are high pour point, low oxidative stability, and limited viscosity range. In this paper, we evaluate and compare the rheological properties of rice bran oil (RBO) with various proportions of low-density polyethylene (LDPE) and ethyl vinyl acetate (EVA) separately. The thermal stability also has been tested in this paper. Both the polymers have different mode of improving the viscosity and LDPE is found to be a viscosity index booster. The percentage improvement in viscosity for various proportions of polymers has been evaluated at various temperatures. It is seen that LDPE is more suited for engine oil applications since the high temperature rheology is more important in the selection of these lubricants. The viscosity variation of biolubricant formulations with temperature were validated with Walther equation. The biodegradability of both the polymers was estimated and compared with a commercially available mineral oil. The addition of EVA and LDPE in RBO reduces the biodegradability to a smaller extent but it is better than commercially available mineral oil SAE20W40.

Suitable additives for vegetable oil‐based automotive shock absorber fluids: an overview

“…16,31,65,71 Low-density polyethylene is another excellent VI improver that can be recommended for ASA fluids formulation because of its good behaviour, including moderate rate of increasing viscosity at 40°C, but significantly high rate of raising it at 100°C, as was tested in rice bran oil. 76 This VM, unlike EVA, showed no negative impact on the peak and onset temperatures of the rice bran oil.…”

“…revealed that 0.5 to 5% (styrene‐butadiene‐styrene) improved the viscosity of high‐oleic sunflower oil by 1.7 to 276% at 40°C, while in a subsequent publication by the same authors, 3 to 4% (w/w) EVA was reported to improve the viscosities at 40°C of sunflower, high‐oleic sunflower and soybeans oils by 330 to 420%, and significantly that of castor oil . EVA and low‐density polyethylene have been reported to be good viscosity modifiers in rice bran oil . In addition to its efficient viscosity modification, EVA at 4%(w/w) in combination with ethyl cellulose (EC) at 1%(w/w), tremendously added to the tribological value of vegetable oil .…”

“…Styrene esters, polymethacrylate and polyacrylates can be very suitable for vegetable oil‐based ASA fluids formulation because of their potentials to promote the low flow properties and discourage corrosion activities of the oil . Low‐density polyethylene is another excellent VI improver that can be recommended for ASA fluids formulation because of its good behaviour, including moderate rate of increasing viscosity at 40°C, but significantly high rate of raising it at 100°C, as was tested in rice bran oil . This VM, unlike EVA, showed no negative impact on the peak and onset temperatures of the rice bran oil.…”

“…75 EVA and low-density polyethylene have been reported to be good viscosity modifiers in rice bran oil. 76 In addition to its efficient viscosity modification, EVA at 4%(w/w) in combination with ethyl cellulose (EC) at 1%(w/w), tremendously added to the tribological value of vegetable oil. 77 However, EVA may not be so suitable were lowtemperature fluidity is critical because it negatively impacts the PPs of most VOs and had been noted to produce an unwanted viscosity rise at 13°C in high-oleic sunflower oil.…”

Styrene butadiene rubber as a viscosity improver: Experimental investigations and quantum chemical studies

“…9 Combination of EVA and low-density polyethene (LDPE) is suggested as a viscosity index improver for rice bran oil based lubricant. 10 EVA and ethyl cellulose (EC) are added to improve the viscosity in high oleic sunflower, soybean, and castor oils. 6 It has been shown that some acrylate-based polymers can enhance the viscosity as well as depress pour point in lube oil.…”