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294 Lubricant Additives: Chemistry and Applications
viscosity at low temperatures than noncrystalline or amorphous copolymers of similar molecular
weight. For this reason, the class of EP copolymers having ethylene content greater than ∼60 wt%
are often called low-temperature OCPs or LTOCPs. A rheological comparison of two LTOCPs
and one conventional OCP viscosity modi er in several SAE 5W-30 oil formulations is seen in
Figures 10.10 and 10.11. These data illustrate the low-temperature rheological bene ts of LTOCPs.
A number of workers have cautioned, however, that the long ethylene sequences of LTOCPs
are similar in structure to paraf n wax and can interact with waxy base oil components at low
temperatures. In many cases, they require specially designed pour point depressants (PPDs) to
function properly in certain base stocks. Thus, LTOCP viscosity modi ers have been impli-
cated in problems such as MRV failures in comingled fresh oils [105] and used passenger car
lubricants [106,107].
FIGURE 10.10 Cold cranking simulator (CCS) viscosity for six SAE 5W-30 lubricant formulations, each
blended with one of three viscosity modi ers: LTOCP1, LTOCP3, or OCP1. Within each base oil type, the
ratio of high and low-viscosity base oils was kept constant.
2000 2500 3000 3500 4000
Sun Tulsa
Exxon
Chevron RLOP
Sun HPO
Mobil Paulsboro
Safety Kleen
CCS viscosity (mPa s) at −25°C
LTOCP1
LTOCP3
OCP1
FIGURE 10.11 Mini-rotary viscosity results for six SAE 5W-30 lubricant formulations, each blended with
one of three viscosity modi ers: LTOCP1, LTOCP3, or OCP1. Within each base oil type, the ratio of high and
low-viscosity base oils and the type and concentration of pour point depressant were held constant.
0 10,000 20,000 30,000 40,000 50,000 60,000
Sun Tulsa
Exxon
Chevron RLOP
Sun HPO
Mobil Paulsboro
Safety Kleen
MRV TP-1 (mPa s) at −35°C
LTOCP1
LTOCP3
OCP1
Yield stress failures
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Olefi n Copolymer Viscosity Modifi ers 295
10.5.2.2 High-Temperature Rheology
Copolymer composition has less in uence on high-temperature rheological behavior than it has at
low temperatures, partly because lightly crystalline OCPs have melting points well below 100°C
[97]. Since both high-temperature KV and high-temperature high-shear rate viscosity (HTHS) are
used to classify multigrade engine oils [104], it is important to understand how copolymer composi-
tion and molecular weight in uence these key parameters.
10.5.2.2.1 Kinematic Viscosity
For both economic and performance reasons, it is desirable to limit the amount of polymer needed to
achieve a given set of rheological targets. Therefore, it is important to quantify the effects of molecular
weight, molecular weight distribution, and branching on thickening ef ciency. Thickening ef ciency
has been de ned in many ways, but the most common de nitions are (1) the amount of polymer nec-
essary to increase the KV of a reference oil to a certain value or (2) the KV or speci c viscosity (see
Section 10.5.2.1) of a given polymer concentration in a reference oil. For polymers of equal molecular
weight, thickening ef ciency increases with ethylene content and is highest for copolymers with nar-
row molecular weight distributions [1,2]. In Figure 10.12, a plot of intrinsic viscosity versus weight
average molecular weight (M) demonstrates the familiar Mark–Houwink power law relationship:
[]
′
⫽ KM
a
where K′ and a are constants.
Assuming a single value for the power law constant a = 0.74, Crespi et al. [5] published a table of
K′ values as a function of ethylene content, which is reproduced in Table 10.2. This clearly shows
that thickening ef ciency can be improved by increasing ethylene concentration.
This is further illustrated by plotting data from Kapuscinski et al. [98] in Figure 10.13. The
80 mol% ethylene copolymer requires less polymer to achieve a target viscosity than a 60 mol%
copolymer; therefore the former has a higher thickening ef ciency than the latter.
FIGURE 10.12 Intrinsic viscosity as a function of weight average molecular weight for EP copolymers
of narrow polydispersity (M
w
/ M
n
∼ 2). (Spiess, G.T., Johnston, J.E., and VerStrate, G., Addit. Schmierst.
Arbeits uessigkeiten, Int. Kolloq., 5th, 2, 8.10-1, Tech. Akad. Esslingen, 1986. Reproduced with permission
of ExxonMobil Chemical Company.)
10
1.0
0.1
0.01
10
3
10
4
10
5
10
6
Weight average molecular weight
Intrinsic viscosity (dL/g) Decalin 135°C
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296 Lubricant Additives: Chemistry and Applications
Long-chain branching has a directionally detrimental effect on thickening ef ciency for poly-
mers of equal molecular weight. This is not surprising, since the average chain end-to-end distance
of a random coil in solution is controlled, in large part, by the length of the main chain. Branching
essentially shortens the chain and lowers its hydrodynamic radius. For example, Table 10.3 contains
thickening ef ciency data for two sets of noncrystalline OCP viscosity modi ers, one linear and the
other containing 2% branching agent, each set differing only in molecular weight.
10.5.2.2.2 High-Temperature, High-Shear Rate Viscosity
Since concentric journal bearings operate in the hydrodynamic or elastohydrodynamic lubrication
regimes, oil lm thickness is a critical factor in uencing wear [108,109]. For this reason, SAE J300
speci es a minimum HTHS viscosity for each viscosity grade [104]. HTHS viscosity is measured
at very high shear rates and temperatures (10
6
s
–1
and 150°C, respectively), which is similar to the
TABLE 10.2
Mark–Houwink K′ Constants for E/P Copolymers Containing
Different Mole Percentages of Ethylene (a = 0.74)
Mol% ethylene K′ × 10
4
Mol% ethylene K′ × 10
4
5 2.020 55 3.020
10 2.115 60 3.140
15 2.205 65 3.260
20 2.295 70 3.385
25 2.390 75 3.515
30 2.485 80 3.645
35 2.585 85 3.790
40 2.690 90 3.940
45 2.795 95 4.240
50 2.910 ——
Source: Adapted from Crespi, G., Valvassori, A., and Flisi, U., Stereo Rubbers,
W.M. Saltman, ed., Wiley-Interscience, New York, NY, 365–431, 1977.
FIGURE 10.13 Polymer concentration needed to raise the kinematic viscosity of a 130N base oil to 11.5 cSt.
(Data from Kapuscinski M.M., Sen, A., and Rubin, I.D., Soc. Automot. Eng. Tech. Paper Ser. No. 892152, 1989.)
0
0. 5
1
1. 5
2
0 100 200 300 400 500
M
w
× 10
−3
Polymer Concentration (wt%)
60 mol%
ethylene
80 mol%
ethylene
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Olefi n Copolymer Viscosity Modifi ers 297
ow environment in an operating crankshaft bearing at steady state. At these rates of deformation,
most high-molecular-weight polymers will align with the ow eld [110], and a temporary reduction
in viscosity is measured. The difference between low-shear rate viscosity and HTHS at 150°C is
termed temporary viscosity loss (TVL) or percent temporary viscosity loss (relative to the low-shear
rate KV). As is true for most polymers [110], TVL is proportional to molecular weight [1] as seen
in Table 10.4. For polymers of equal weight average molecular weight, those with narrow molecular
weight distributions undergo less TVL than those with broad M
w
/ M
n
values [1].
HTHS viscosity can be adjusted by increasing the viscosity of the base oil or by increasing the
viscosity modi er concentration, as shown in Figure 10.14. Since the formulation also has to meet
KV and CCS viscosity limits, there is often only limited exibility to adjust HTHS viscosity within
the bounds of a given set of base oils and additives.
10.5.2.2.3 Permanent Shear Stability
The tendency of an OCP molecule to undergo chain scission when subjected to mechanical forces
is dictated by its molecular weight, molecular weight distribution, ethylene content, and degree of
long-chain branching. Mechanical forces that break polymer chains into lower-molecular-weight
fragments are elongational in nature, causing the molecule to stretch until it can no longer bear the
load. This loss in polymer chain length leads to a permanent degradation of lubricant viscosity at
all temperatures. In contrast to temporary shear loss, permanent viscosity loss (PVL) represents an
irreversible degradation of the lubricant and must be taken into account when designing engine oil
for commercial use.
PVL is similar to TVL, except that the viscosity loss is measured by KV before and after shear.
Permanent shear stability is more commonly de ned by the permanent shear stability index (PSSI)
or simply SSI, according to ASTM D6022 as follows:
PSSI V V V V⫽⫽⫻SSI 100
Sb00
⫺⫺
()()
TABLE 10.3
Thickening Effi ciency of Linear and Branched
OCP Viscosity Modifi ers
M
w
Linear Branched
230,000 13.50 12.03
180,000 11.17 10.87
Note: Thickening ef ciency is de ned as the kinematic viscosity (at
100°C) of a 1.0 wt% polymer solution in 6.05 cSt mineral oil.
TABLE 10.4
Rheological Comparison of Lubricants Containing OCP Viscosity Modifi ers Differing in
Molecular Weight
Viscosity Modifi er
Weight Average
Molecular Weight PSSI
Capillary Viscosity
(cP) at 150°C
HTHS (cP)
at 150°C % TVL
OCP1 160,000 45 5.33 3.43 36
OCP2 80,000 30 5.33 3.77 29
OCP3 50,000 22 5.33 3.88 27
Source: Adapted from Spiess, G.T., Johnston, J.E., and VerStrate, G., Addit. Schmierst. Arbeits uessigkeiten, Int. Kolloq.,
5th, 2, 8.10-1, Tech. Akad. Esslingen, 1986.
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298 Lubricant Additives: Chemistry and Applications
where
V
o
= viscosity of unsheared oil
V
s
= viscosity of sheared oil
V
b
= viscosity of the base uid (without polymer)
SSI represents the fraction of viscosity contributed by the viscosity modi er that is lost during
shear. SSI is proportional to log
10
molecular weight (M
w
), as shown in Figure 10.15. Commercial
OCP viscosity modi ers have SSI values in the range of 23–55.
FIGURE 10.14 The effects of base oil composition and viscosity modi er concentration on HTHS viscosity.
SAE 15W-40 engine oil consisting of European API Group I base oils (150N + 600N), an ACEA A3-98/B3-98
quality performance additive, an oil diluted amorphous OCP viscosity modi er, and a pour point depressant.
Bars marked with an asterisk comply with ASTM D445 and D5293 limits for SAE 15W-40 oils.
49.2
36.5
20.0
11.2
0.0
4.8
5.8
6.8
7.8
8.8
3.5
3.75
4
4.25
4.5
4.75
5
HTHS Viscosity (cP)
% 600N Oil
%Viscosity modifier
*
*
*
*
*
FIGURE 10.15 Relationship between weight average molecular weight and SSI (ASTM D3945) for a series
of OCP viscosity modi ers.
0
10
20
30
40
50
60
5.0 5.1 5.2 5.3 5.4 5.5 5.
6
Log weight average molecular weight
Shear stability index
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Olefi n Copolymer Viscosity Modifi ers 299
Although ASTM D6022 provides a de nition for SSI, it is important to recognize that the only
component that is responsible for viscosity loss during shear is the high-molecular-weight poly-
mer. If the additive for which SSI is calculated happens to be a concentrated polymer solution in
oil, according to the strict de nition of ASTM D6022, the composition of the base uid does not
include the viscosity modi er (VM) diluent oil. Since the diluent oil viscosity is usually lower than
the base blend viscosity for most viscosity grades, V
b
is higher than it would be if the VM diluent
oil viscosity was factored into V
b
. For example, take an SAE 15W-40 engine oil formulated with
a liquid OCP concentrate containing 10 wt% polymer in a 5.1 cSt mineral oil. V
0
and V
s
are 15.2
and 12.8 cSt, respectively. The base blend viscosity (when the VM component is a liquid) is 9.4 cSt.
When the VM component is de ned as the solid polymer, V
b
is 9.15 cSt. Calculated shear stability
index values are 41.4 and 39.7, respectively. Thus, the numerical value of SSI is dependent on the
de nition of the polymeric additive in question.
The concept of “stay-in-grade” is generally used to refer to a lubricating oil, when tested in
vehicles or laboratory shearing devices, which maintains its KV within the limits of its original SAE
viscosity grade. The problem with viscosity measurements of engine drain oils is that many factors
other than permanent polymer shear in uence viscosity—such as fuel dilution, oxidation, and soot
accumulation. Therefore, it is customary to measure PVL after shear in a laboratory rig, the most
common being the Kurt Orbahn test, ASTM D6278. Several reviews of methods for determining
the shear stability of polymer-containing lubricating oils have been published [111–113].
Selby devised a pictorial scheme for mapping the effects of shear rate and PVL on high-
temperature viscosity, the viscosity loss trapezoid (VLT) [114], shown in Figure 10.16. The corners
of the trapezoid are de ned by viscosity data, and the points are connected by straight lines. Note
that the straight lines do not imply that there is a linear relationship between viscosity and shear
rate. The VLT is a convenient graphical representation of the temporary and permanent shear loss
characteristics of polymer-containing oils. Molecular weight degradation causes a permanent loss
in both KV and HTHS, but the magnitude of the former is always larger than the latter. The shape
of the VLT is the characteristic of polymer chemistry and molecular weight.
It is experimentally observed [115] that the Kurt Orbahn shear test breaks molecules above a
threshold molecular size; molecules smaller than the threshold value are resistant to degradation.
Selby [114] uses this observation to derive certain qualitative conclusions of the polymer molecular
weight distribution from the shape of the VLT.
10.5.3 EFFECT OF DIENE ON THERMAL/OXIDATIVE STABILITY
There has been little solid scienti c data published in the literature to compare the relative thermal/
oxidative stability of oil solutions containing E/P copolymers versus EPDM terpolymers. Marsden [2]
FIGURE 10.16 Viscosity loss trapezoid, per Selby: (a) Fresh oil viscosities and (b) oil viscosities after per-
manent shear. (Selby, T.W., Soc. Automot. Eng. Tech. Paper Ser. No. 932836, 1993.)
Shear rate
High
(HTHS)
Low
(KV)
Absolute viscosity (cP)
150°C
(a)
(b)
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300 Lubricant Additives: Chemistry and Applications
states that “introduction of a termonomer … can … detrimentally affect shear and oxidation stability,
dependent on the monomer,” but he offers no data. Others [5,27] cite high-temperature aging experi-
ments on solid rubber specimens, which demonstrate that EP copolymers are more stable (in terms
of tensile properties) than EPDM terpolymers of similar E/P ratio. Copolymers containing higher
levels of ethylene are claimed to have better thermal/ oxidative stability than more propylene-rich
copolymers, presumably due to the lower concentration of oxidatively labile tertiary protons contrib-
uted by the propylene monomer. High thermal stresses are suf cient to promote hydrogen abstraction
by a free radical mechanism. The relative susceptibility of protons to hydrogen abstraction follows
the classical order tertiary > secondary > primary. In the presence of oxygen, peroxy radicals are
formed, which can accelerate the degradation process.
Despite these suggestions that diene-containing E/P copolymers may be less thermally stabile
than EP copolymers, the author is not aware of any de nitive studies that have shown that EPDM
viscosity modi ers are more likely to degrade in service than EP copolymers. Indeed, engine oils
formulated with both types have been on the market for years.
10.5.4 COMPARATIVE RHEOLOGICAL PERFORMANCE IN ENGINE OILS
The most in uential factors governing the rheological performance of OCPs in engine oils are
molecular weight and monomer composition. The effects of molecular weight and molecular
weight distribution were discussed in Section 10.5.2.3, and the in uence of E/P ratio on low-
temperature rheology was covered in Section 10.5.2.1. In this section, two comparative rheologi-
cal studies are presented to further illustrate the links between OCP structure and rheological
performance.
10.5.4.1 Comparative Study of OCP Viscosity Modifi ers in a
Fixed SAE 5W-30 Engine Oil Formulation
There are two ways to compare the relative performance of several viscosity modi ers. One is to
choose a xed engine oil formulation where the base oil composition and additive concentrations
are held constant, and the VM level is adjusted to achieve a certain 100°C KV target. The other is
to adjust both base oil composition and VM concentration to achieve predetermined KV and CCS
viscosity targets. Section 10.5.4.1 offers an example of the rst approach and Section 10.5.4.2 illus-
trates the second approach.
Four OCP viscosity modi ers were blended into an SAE 5W-30 engine oil composition con-
sisting of a 95/5 w/w blend of Canadian 100N/250N mineral base stocks, an ILSAC GF-2 quality
performance additive, and a polyalkylmethacrylate PPD. The viscosity modi ers are described in
Table 10.5. OCP1 and OCP2 are high SSI polymers differing in both E/P ratio and diene content.
OCP3 and OCP4 are progressively more shear stable and have essentially 0% crystallinity.
Rheological data are summarized in Table 10.6. Comparing OCP1 and OCP2, the former is a
more ef cient thickener because it contains no long-chain branching (no diene monomer) and it has
TABLE 10.5
Properties of OCP Viscosity Modifi ers Used in Table 10.6
Viscosity Modifi er Code
Shear Stability Index
(ASTM D6278) Copolymer Type
OCP1 55 EP, LTOCP
OCP2 50 EPDM, amorphous
OCP3 37 EP, amorphous
OCP4 25 EP, amorphous
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Olefi n Copolymer Viscosity Modifi ers 301
a higher ethylene content (see Figure 10.13). The latter property also manifests itself in lower CCS
viscosity. The MRV viscosity is also lower for OCP1 relative to the other amorphous OCPs, but this
is highly dependent on the particular PPD that was chosen for this study. The fact that most of the
oils displayed yield stress failures at –35°C shows that the PPD was not optimized for this particular
set of components.
As SSI decreases from OCP1 to OCP4, the polymer concentration needed to reach a KV target
of 10 cSt increases. In other words, polymer thickening ef ciency is proportional to shear sta-
bility index. Among the noncrystalline OCPs, increasing polymer level causes the CCS viscosity
to increase. Since all oils were formulated with the same base oil composition, high- temperature
HTHS is relatively constant, independent of OCP type. OCP4, the lowest molecular weight polymer,
should have the lowest degree of TVL, and it indeed has the highest HTHS viscosity of the group.
10.5.4.2 Comparative Study of 37 SSI OCP Viscosity Modifi ers
in an SAE 15W-40 Engine Oil Formulation
In this example, the base oil ratio and polymer concentration were adjusted to achieve the following
targets: KV = 15.0 cSt and CCS = 3000 cP at –15°C. The base stocks were American Petroleum
Institute (API) Group I North American mineral oils, the additive package was of API CH-4 qual-
ity level, and the PPD was a styrene ester type that was optimized for these base oils. All viscosity
modi ers (see Table 10.7) were nominally 37 SSI according to ASTM D6278. Rheological results
are summarized in Table 10.8.
OCP3 is the same polymer as in Table 10.5. Although OCP8 and OCP9 are semicrystalline
LTOCPs, they represent different manufacturing technologies, broadly described in Figures 10.4
and 10.5, respectively. Incidentally, OCP1 in Table 10.5 was also manufactured by the tubular reac-
tor technology described in Figure 10.5.
TABLE 10.6
Rheological Properties of SAE 5W-30 Engine Oils Containing Different OCP
Viscosity Modifi ers
OCP1 OCP2 OCP3 OCP4
Polymer content (wt%) 0.58 0.71 0.73 1.05
Kinematic viscosity (cSt) at 100°C 10.17 10.09 9.99 10.10
Viscosity index 156 160 160 158
CCS viscosity (cP) at −25°C 3080 3280 3510 3760
MRV viscosity (cP) at −30°C 13,900 26,500 26,700 28,100
MRV viscosity (cP) at −35°C 40,100 Yield stress Yield stress Yield stress
HTHS (cP) 2.95 2.88 2.96 3.07
TABLE 10.7
OCP Viscosity Modifi ers Used in
Rheological Study in Table 10.8
Viscosity Modifi er Code Copolymer Type
OCP7 EPDM, amorphous
OCP3 EP, amorphous
OCP8 EPDM, LTOCP
OCP9 EP, LTOCP
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302 Lubricant Additives: Chemistry and Applications
The rheological data in Table 10.8 further illustrate several features of LTOCPs mentioned
earlier. Their inherently lower CCS viscosity contributions permit the greater use of higher- viscosity
base oils, which can be bene cial in meeting volatility requirements. The low-temperature MRV
performance of OCP9 was far inferior to that of the other copolymers, indicating that the PPD
chosen for this particular study was not optimized for OCP9 in these base stocks.
Another polyalkymethacrylate PPD was found to bring the MRV viscosity of the OCP9
formulation down to 7,900 and 18,000 cP at –20 and –25°C, respectively. More about interaction
with PPDs is discussed in Section 10.5.5.
Again, the higher thickening ef ciency of EP copolymers versus EPDMs of similar molecular
weight (shear stability) is clearly demonstrated in Table 10.8. Another feature worth noting is that
increasing base oil viscosity can nudge HTHS viscosity upward (compare OCP7 with OCP8 or
OCP3 with OCP9).
10.5.5 INTERACTION WITH POUR POINT DEPRESSANTS
Although base oil and VM play a role in determining low-temperature oil pumpability, the PPD
provides the primary control in this area. SAE J300 [104] speci es the MRV test (ASTM D4684)
as the sole guardian of pumpability protection, although it acknowledges that other tests may also
be useful in the development of lubricants from new components. The Scanning Brook eld test
(ASTM D5133) and Pour Point (ASTM D5873), although not required within SAE J300, are often
contained in other standards established by original equipment manufacturers, oil marketers, and
governmental agencies and, therefore, must also be considered in the development of modern
engine oils.
Advances in base oil technology have led, in recent years, to a wide range of mineral and syn-
thetic lubricant base stocks [116], classi ed as API Group I, II, III, IV, and V stocks. The API system
classi es oils according to viscosity index (VI), saturates content, and sulfur level. Group I mineral
oils are de ned as having <90% saturates, VI >80 and more than 0.03% sulfur. Groups II and III
oils have <0.03% sulfur and >90% saturates, but they differ mainly in VI. Group II oils have VI
>80, whereas Group III stocks have VI values in excess of 120.
Formulating these conventional and highly re ned oils to meet all the rheological requirements
of SAE J300 is not always straightforward. An important aspect of base oil technology that is not
embodied within the API Group numbering scheme is the type of de-waxing process or processes
employed. It is well known [117–123] that the low-temperature oil pumpability performance of
engine oils is often impeded by nucleation and growth of wax crystals, which can coalesce and
restrict the ow of oil at low temperatures. The type and amount of wax that forms dictates the
TABLE 10.8
Rheological Properties of SAE 15W-40 Engine Oils Containing
Different OCP Viscosity Modifi ers
OCP7 OCP3 OCP8 OCP9
Polymer content (wt%) 0.95 0.85 0.85 0.64
150N base oil percentage 76 76 70 70
600N base oil percentage 24 24 30 30
Kinematic viscosity (cSt) at 100°C 15.04 14.97 15.25 15.12
Viscosity index 141 140 140 135
CCS viscosity (cP) at −15°C 3,080 3,040 3,070 3,010
MRV viscosity (cP) at −20°C 10,000 9,900 8,800 Solid
MRV viscosity (cP) at −25°C 20,500 18,600 18,300 Solid
HTHS (cP) 4.17 4.38 4.25 4.42
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Olefi n Copolymer Viscosity Modifi ers 303
type and concentration of PPD that will be effective in keeping wax crystals small so that they do
not form network structures and lead to high viscosity and yield stress. Both the feedstocks and de-
waxing steps used in the manufacture of a given base oil determine wax composition and, in turn,
PPD response.
Certain types of viscosity modi ers can interact with base oils and PPDs at low temperatures
and can lead to excessively high MRV viscosities in some situations (see, for example, OCP9 in
Table 10.8). Formulating with amorphous OCPs has not, in the author’s experience, posed many
dif culties. Conversely, LTOCPs possess longer ethylene sequences that have the potential to
interact with wax crystals at low temperatures. Several reports in the literature [66,76] suggest that
high-ethylene OCPs can, under certain circumstances, interact negatively on MRV viscosity and
yield stress and may be more sensitive to the type of PPDs that will be effective in some formulat-
ing systems.
A previously unpublished study of low-temperature interactions among base oils, OCP visco-
sity modi ers, and PPDs was carried out in the author’s laboratory using components listed in
Tables 10.9 through 10.11.
Fully formulated SAE 5W-30 and 15W-40 engine oils were blended using performance additive
packages DI-1 (at 11 wt%) and DI-2 (at 13 wt%); API SJ quality and CH-4 quality, respectively; and
all combinations of base oil, VM, and PPD.
TABLE 10.9
Base Oils Used in Low-Temperature Viscosity Modifi er/Pour Point Depressant
Interaction Study
Base Oil Code
(API Group) Saturates (wt%)
Kinematic Viscosity
(cSt) at 100°C Sulfur (wt%) Viscosity Index
CCS Viscosity
(cP) at –25°C
B1-L (I) 73.6 3.88 0.276 104 1170
B1-M (I) 71.8 5.15 0.553 102 4060
B1-H (I) 61.8 12.10 0.381 97 —
B2-L (I) 75.2 4.18 0.193 105 1510
B2-M (I) 75.0 4.91 0.544 106 3060
B2-H (I) 72.3 12.73 0.412 99 —
B3-L (II) 100 4.20 0.006 100 1570
B3-M (II) 100 5.49 0.011 117 2430
B3-H (II) 100 10.72 0.016 98 —
B4-L (III) 100 4.50 0.007 123 1120
B4-H (III) 100 6.49 0.006 131 2710
TABLE 10.10
Viscosity Modifi ers Used In
Low-Temperature Viscosity
Modifi er/Pour Point Depressant
Interaction Study
VM Code OCP Type
SSI (ASTM
D6278)
VM-1 Amorphous 37
VM-2 LTOCP 35
VM-3 LTOCP 37
TABLE 10.11
Pour Point Depressants Used In
Low-Temperature Viscosity Modifi er/Pour
Point Depressant Interaction Study
Pour Point Depressant Code Chemistry
PPD-1 Poly(styrene-maleate ester)
PPD-2 Poly(alkylmethacrylate)
PPD-3 Poly(styrene-maleate ester)
PPD-4 Poly(alkylmethacrylate)
CRC_59645_Ch010.indd 303CRC_59645_Ch010.indd 303 12/6/2008 10:10:17 AM12/6/2008 10:10:17 AM