Perfecting the Lubricant Wheel through Macromolecular DesignPacific Northwest National LaboratoryJoshua W. Robinson and Lelia Cosimbescu* (Synthesis)Oak Ridge National LaboratoryYan Zhou and Jun Qu (Friction and Wear)Brian West (Engine Testing)

1 PNNL-SA-117691

Motivation

There are 244 million cars and trucks in the U.S.

They consume 10.9 million barrels of oil per day

A 3.5% fuel savings would result in big savings

139 million barrels of oil per year

IC system energy balance: 16.5 % of fuel energy is lost to friction

11.5% in engine, 5% in powertrain

Experts project that these losses can be reduced by about 20% (3.5%

overall fuel savings)

Key pathways for friction reduction include: novel base stocks/VMs,

reduced oil viscosity and improved friction and wear additives

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Natural Thinning Effect

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Mechanism of Intramolecular VM

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Mechanism of Intermolecular VM

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Conventional and Modern VMs

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Linear Comb Radial/Star HyperbranchedComb Star Branched

Increasing Viscosity Influence Increasing Life Cycle

Greater Chain EntanglementLeads To

Mechanical Shear Degradation VS.

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Enhanced Surface Performance Model

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Friction and Viscosity Modification

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Manipulating the Degree of Branching

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Topology Sweet Spot

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Altering the Topology

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Friction to VI Enhancement

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Tailored Polarity

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Overview

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Benchmark 1 and 2

Star-shaped VIs

Hyper-Branched FMs

Branched VMs Multi-arm VI

VI performance: Governed by Mw Influenced by Polarity

Friction performance: Governed by topology Influenced by Mw &

polarity

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Initial Viscosity Screening in Group I. (2% w/w)

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30.2

289.7

35.2 32.5 31.2

106.8

69.6

96.5

5.1

39.1

6.4 5.3 5.317.5 10.3 14.0

0

50

100

150

200

250

300

350

0

50

100

150

200

250

Group 1 Bench. 1 Bench. 2 53-83 53-161 53-159 53-160 53-165

Visc

osity

(cSt

)

Visc

osity

Inde

x #

Group I, Benchmark 1 and 2, and Multi-Branched Polymer Blends.

Viscosity Index

cSt @ 40 °C

cSt @ 100 °C

Low MwLow VI

Robinson; Zhou; Bhattacharya; Erck; Qu; Bays; Cosimbescu. Sci. Rep. 2016, 6, 18624.

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Initial Friction Screening in Group I at 23 °C. (2% w/w)

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0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.1 1

μ

speed (m/s)

Group I

159 @ 2 wt %

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.1 1

μ

speed (m/s)

Group I

Bench. 2 @ 1.67 wt %

Mixed HydrodynamicBoundary

106 cSt @ 23 oC 159 cSt @ 23 oC

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Initial Friction Screening in Group I. (2% w/w)

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-0.03

-0.02

-0.01

0

0.01

0.1 1

μ re

duci

ton

speed (m/s)

Normalized Friction Reduction @ 23 °C

Bench. 2

53-161

53-159

53-160

-0.03

-0.02

-0.01

0

0.01

0.1 1

μ re

duci

ton

speed (m/s)

Normalized Friction Reduction @ 100 °C

Bench. 2 53-161

53-159 53-160

Best Friction Performance by:

Bench. 2 53-161 53-159/160

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Structure-Performance Studies

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18.8

100.8

33.3

24.0 24.4 26.6 28.3 26.930.4

4.2

17.3

8.3 5.3 5.4 6.1 6.4 6.2 7.0

0

20

40

60

80

100

0

50

100

150

200

250

Group III Bench. 1 Bench. 2 88-56CR 71-83R 88-31 53-126 88-32 88-15

Visc

osity

(cSt

)

Visc

osity

Inde

x #

Group III, Benchmark 1 and 2, and Star-Shaped PAMAs.

Viscosity Index

cSt @ 40 °C

cSt @ 100 °C

245 kDa3-arm

159 kDa4-arm

122 kDa3-arm

78 kDa3-arm

265 kDa6-arm

295 kDa3-arm

𝑀𝑀𝑤𝑤 Dominates VI behavior…3-arm 4-arm 6-arm

Increasing Mw

Robinson; Zhou; Qu; Erck; Cosimbescu. J. Appl. Polym. Sci. 2016, DOI: 10.1002/APP.43611.PNNL-SA-117691

Structure-Performance Studies

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33.3 30.4 31.423.8 23.0 23.3

26.723.1 25.5 23.8 23.4 24.4

8.3 7.0 7.1 5.9 5.3 5.5 6.0 5.1 5.8 5.5 5.2 5.5

0

20

40

60

80

100

0

50

100

150

200

250

Visc

osity

(cSt

)

Visc

osity

Inde

x #

Benchmark 2, and star-shaped co-P[DMA]/[Polar MA].

Viscosity Index

cSt @ 40 °C

cSt @ 100 °C

Polarity Suppressed VI values…3-arm 4-arm 6-arm

Increasing [Polar]

Robinson; Zhou; Qu; Erck; Cosimbescu. Publication in progress.

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Friction Performance at 23 °C

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Homo-Polymers Co-Polymers

-0.03

-0.02

-0.01

0

0.01

0.1 1

μ re

duci

ton

speed (m/s)

Normalized Friction Reduction @ 23 °C

Bench. 2

88-31

88-15

88-15 88-31

-0.03

-0.02

-0.01

0

0.01

0.1 1

μ re

duci

ton

speed (m/s)

Normalized Friction Reduction @ 23 °C

Bench. 2

88-35

71-100

88-3571-100

-0.03

-0.02

-0.01

0

0.01

0.1 1μ

redu

cito

n

speed (m/s)

Normalized Friction Reduction @ 23 °C

Bench. 2

88-33

Reduced Friction at 23 °C

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Bench. 2

88-33

Grafted from Branched Corepseudo multi-arm star

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Technical AccomplishmentsEngine Testing

19BLB: baseline lube before test: BLA: baseline lube after test

Chosen formulation:1.538% PNNL polymer, 10.1% HiTec 11100, Yubase411 gallons of final lubricant were prepared

City Fuel Economy improves 2.3% (composite 3-bag result)

4% on the cold Bag 1Less than 2% on Bags 2 and 3

HFET fuel economy improves 1.7%SSFE improvement ranges from 1 to 2%. Higher improvement measured at lower speeds

3-Phase Federal Test Procedure (ORNL)Reference Oil 20W30

FTP Test Results for PNNL Lube versus average of BLB and BLA runs. Range bars show maximum and minimum of 5 tests

Sequence VI-E (SwRI)Reference oil 20W30

FEI1 80/20 Eng Hr Adjusted 1.11%

FEI2 10/90 Eng Hr Adjusted 0.90%

FEI Sum 2.01%

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Summary

Investigated polymers as engine oil VMs and FMsCompetitive VI performance to commercial VMs

Branched, star-shaped, and multi-arm polymersOutperformed commercial additives in friction

Hyper-branched polymersOverall Fuel Economy Gain of 1.7% with multi-arm starsOngoing structure-performance studies with hyperbranched systems

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AcknowledgmentsFunding Source

DOE: Kevin Stork (Vehicle Technology Office)NETL/TARDEC

CollaborationEvonik: David Gray, JoRuetta EllingtonAfton Chemical Energetics: Dr. Ewa Bardasz

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