Engineering topics

Robinson, Joshua W.

Publications and source records attributed to Robinson, Joshua W..

7 records

DOE OSTI2018

Polymer Architecture: Does it Influence Shear Stability?

Hyperbranched and linear poly(alkyl methacrylate)s with and without polycaprolactone grafts were designed and prepared via a core-first strategy, then evaluated with respect to their rheology and shear stability performance. The focus of this work was to study the effect of architecture on mechanical shear stability, as it relates to lubricant performance. The polymers were prepared from functionalized macroinitiators subsequently subjected to ATRP/ARGET-ATRP conditions with dodecyl methacrylate and 2-ethylhexyl methacrylate mixtures. As expected, most compounds displayed an increased viscosity index along with increasing molecular weights. The inclusion of polycaprolactone appears to have enhanced the viscosity index in select samples. Although the hyperbranched polymers studied here varied in the number of arms from about twenty to one (linear), the data presented supports the empirical understanding that shear stability is mainly influenced by molecular weight and not architecture or topology. The polymers with caprolactone blocks demonstrated a positive effect on the shear stability, as in possessing the lowest viscosity loss values which were four times lower than the other compounds included in this study as well as the benchmark.

Cosimbescu, Lelia↗

DOE OSTI2018

Synthesis of a biofuel target through conventional organic chemistry

In this work, the biofuel target compound 2-ethyl-5,5-dimethylcyclopenta-1,3-diene (1) and its exo isomers (9a and 9b), were successfully synthesized via two different pathways from the common intermediate 4,4-dimethylcyclopent-2-ene-1-one (2). The first pathway produced the endocyclic product as a pure isomer via a triflate intermediate obtained from the ketone 2 in 60% yield, followed by copper catalyzed coupling with ethyl magnesium bromide in 63% yield. The second pathway employed a Grignard reaction with ketone 2, which generated an alcohol that was immediately subjected to mild acid catalyzed elimination upon workup of the previous step to yield a primarily a mixture of exo diastereomers 9a and 9b in 77% yield. These targets had their fuel properties characterized in a separate study.

Biofuel↗

DOE OSTI2018

Friction- and Wear-Reducing Properties of Multifunctional Small Molecules

Nitrogen- and oxygen-containing compounds were designed and synthesized, and their tribological performance as multifunctional base oils (MFBOs) for internal combustion engine applications was evaluated. Two of the compounds displayed good rheology without the addition of polymeric viscosity modifiers, with a high viscosity index (VI) above 200.Additionally, all three MFBOs had lower coefficients of friction when compared to well established and accepted benchmarks, and demonstrated wear improvement by a factor of 5.5 to 70 compared to either of the benchmarks. Moreover, the compounds were easily synthesized in one step from commercial intermediates or starting materials. This work demonstrates that careful design of a single molecule might provide the functions of base oil, viscosity modifiers (or viscosity index improvers), anti-wear and friction reducing additives.

Cosimbescu, Lelia↗

DOE OSTI2016

Trends in Thermoresponsive Behavior of Lipophilic Polymers

In an effort to look for correlations between viscosity index trends of polymers in oils and size changes of polymers in solution with temperature, the determination of the size of thermo-responsive polymers of various architectures (linear, comb, star, and hyperbranched) using two experimental techniques – dynamic light scattering and small angle neutron scattering, and predictive molecular dynamics simulations is described herein. The aim of this work was to predict their behavior as viscosity index improvers (VIIs) using these tools which require minimal amounts of material, as opposed to measuring kinematic viscosities, which require multi-gram quantities. Conflicting trends were obtained using the different aforementioned techniques due to the inherent physics of the measurements. While we provide potential explanations for the trends observed, the focus of this work remains the assessment of any of these techniques as a predictive tool for polymer behavior in an oil matrix. It was concluded that none of the aforementioned techniques can entirely predict the polymer behavior as VIIs, at least in the temperature range studied (40 °C to 100 °C).

Bhattacharya, Priyanka↗

DOE OSTI2016

Highly Branched Polyethylenes as Lubricant Viscosity and Friction Modifiers

A series of highly branched polyethylenes (BPE) were prepared and used in a Group I base oil as potential viscosity and friction modifiers. The lubricating performance of these BPEs supports the expected dual functionality. Changes in polarity, topology, and molecular weight of the BPEs showed significant effects on the lubricants’ performance, which provide scientific insights for polymer design in future lubricant development.

Branchedpolyethylene↗

DOE OSTI2016

Modified Thermoresponsive Hyperbranched Polymers for Improved Viscosity and Enhanced Lubricity of Engine Oils

The manuscript captures the chronological succession of the molecular design progression through multiple architectures and topologies of the polymeric viscosity index improvers and their rheology bench test performance. Tribology testing was also performed on selected analogs and their friction and wear was evaluated. Finally, a top performing polymer was selected for engine testing, scaled-up, and its rheological performance in a complete formulation was assessed. The engine performance of the viscosity index improver was examined against an industry-established baseline.

02 PETROLEUM↗

DOE OSTI2016

Dual Functional Star Polymers for Lubricants

Star-shaped poly(alkyl methacrylate)s (PAMAs) with a 3-arm architecture were designed, prepared and their performance as a dual additive (viscosity index improver and friction modifier) for engine oils was evaluated. Furthermore, the structure-property relationships between macromolecular structure and lubricant performance were studied. Several co-polymers of dodecylmethacrylate with polar methacrylates in various amounts and various topologies, were synthesized as model compounds. Star polymers with a polar content of at least 10% effectively reduced the friction coefficient in both mixed and boundary lubrication regime only in block or tapered block topology. However, a polar content of 20% was efficient in reducing friction in both random and block topologies.

Cosimbescu, Lelia↗