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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Bio-oils Research » Research » Publications at this Location » Publication #355360

Research Project: Value-added Bio-oil Products and Processes

Location: Bio-oils Research

Title: Biobased polyphosphonate additives from methyl linoleates

Author
item Biresaw, Girma
item Bantchev, Grigor
item Harry-o`kuru, Rogers

Submitted to: Tribology Transactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: Successful application of farm products in biobased lubricant formulations will provide a number of environmental, health, and economical benefits over petroleum based formulations. Achieving the maximum benefit will require developing fully biobased lubricant formulations, where both the base oil and the additives are biobased. Currently, there are a few commercial biobased base oils that can be used for such purpose. In contrast, there are no commercial biobased additives that can be used to formulate fully biobased lubricant formulations. In the work described here, methyl linoleate, which is obtained from soybean oil and vegetable oils, was chemically modified to produce a series of poly-dialkylphosphonate additives. These new additives were positively identified and characterized using a variety of analytical methods and their additive properties in high oleic sunflower oil (HOSuO) and polyalphaolefin (PAO-6) base oils investigated. The neat poly-dialkylphosphonates displayed higher density, higher kinematic viscosity, higher oxidation stability, and better cold flow properties. As additive (0-10% w/w) in HOSuO, the poly-di-N-butyl phosphonate provided improved oxidation stability and cold flow properties. Poly-di-N-butyl phosphonate blends in HOSuO also showed lower 4-ball anti-wear coefficient of friction (COF) and wear scar diameter (WSD) than corresponding blends with zinc dialkyl dithio phosphate (ZDDP). As an additive (0-10% w/w) in PAO-6 base oil, poly-di-N-butyl phosphonate displayed lower 4-ball anti-wear COF and comparable WSD relative to similar blends of ZDDP in PAO-6. The results indicate that biobased anti-wear additives derived from farm products can provide comparable or better performance than current petroleum based commercial anti-wear additives such as ZDDP. This knowledge is of considerable importance for scientists and engineers engaged in biobased lubricant development.

Technical Abstract: Poly-dialkylphosphonates were synthesized by reacting methyl linoleate with dimethyl, diethyl and di-n-butyl phosphites in the presence of free radical initiator, and positively identified and characterized using GC-MS, NMR (1H, 13C, 31P) and FTIR. Neat poly-dialkylphosphonates and their blends in high oleic sunflower oil (HOSuO) and polyalphaolefin (PAO-6) base oils, were investigated for their physical, chemical and tribological properties. At room temperature, the poly-dialkylphosphonates displayed much better solubility in HOSuO than in PAO-6. Solubility in the base oils increased in the order dimethyl < diethyl < di-n-butyl. Relative to methyl linoleate, the neat poly-dialkylphosphonates displayed higher density, higher kinematic viscosity, higher oxidation stability, and better cold flow (lower pour point and cloud point) properties. As additive (0-10% w/w) in HOSuO, increasing concentration of poly-di-N-butyl phosphonate resulted in increasing onset and peak oxidation temperatures, and decreasing cloud point. Poly-di-N-butyl phosphonate blends in HOSuO also showed lower 4-ball anti-wear coefficient of friction (COF) and wear scar diameter (WSD) than corresponding blends with zinc dialkyl dithio phosphate (ZDDP). As an additive (0-10% w/w) in PAO-6 base oil, poly-di-N-butyl phosphonate displayed lower 4-ball anti-wear COF and comparable WSD relative to similar blends of ZDDP in PAO-6. The results indicate that poly-dialkylphosphonates are promising biobased anti-wear additives with comparable or better performance than current petroleum based commercial anti-wear additives such as ZDDP.