Thermic Behaviour of Two Copolymers Used As Viscosity Improvers For SAE 10W Mineral Oil

BULETINUL Vol.
LX
37 -40 Seria Tehnică
Universităţii Petrol – Gaze din Ploieşti No. 4B/2008
Thermic Behaviour of two Copolymers used as

Viscosity Improvers for SAE 10W Mineral Oil
Ioana Stanciu
Universitatea Bucureşti, Bd. Regina Elisabeta 4-12, 030018, Bucureşti, România

e-mail: ioasta@yahoo.com
Abstract
Differential scanning calorimetry was used to determine the glass transition temperatures of two
copolymers (KELTAN 4200 – a etilene-co-propilene copolymer and INFINEUM SV 260 – a
hydrogenated isoprene-co-styrene one) recommended as viscosity improvers, while TG and DTA to
evaluate their heat resistance.
Key words: Differential scanning calorimetry, glass transition temperatures, heat resistance
Introduction
Differential scanning calorimetry is widely used in the study polymer industry. For the polymer
chemist, DSC is a handy tool for studying curing processes, which allows the fine tuning of
polymer properties. The cross-linking of polymer molecules that occurs in the occurring process
is exothermic, resulting in a positive peak in the DSC curve that usually appears soon after the
glass transition [1-3]. Among the most common analytical techniques, the differential scanning
calorimetry is commonly used for monitoring the exothermal processes because it requires a
small sample size and a short analysis time [4, 5]. Thermic behaviour of two copolymers used as
viscosity improvers for SAE 10W mineral oil were determined using analysis of a DSC, TG and
TGA curves. The thermogrames TG and DTA to evaluate their heat resistance.
The object of the present paper is the determination heat resistance and glass transition
temperatures of two copolymers – recommended as viscosity improvers for multi-grade oils –
for which the global and partial solubility parameters and radii of interaction sphere [6],
rheological behaviour of concentrated solutions [7] and viscosity indices of solutions
copolymers were determined using the ASTM 2270-93 [8].
Experimental detail
The following copolymers were used as viscosity improvers: hydrogenated poly(isoprene-co-

styrene) (Infieum UK LIMITED) – trade name INFINEUM SV 260 and poly(ethylene-co-
propylene) (DSM Elastomers Europe B. V.) – trade name KELTAN 4200.
The experimental thermograms were obtained using a differential scanning calorimeter DSC
DuPont 2000. The DSC/TG and DTA was obtained using under following experimental
38 Ioana Stanciu
conditions: the heating rate 20°C min-1 in non-isothermal conditions, the nitrogen atmosphere,
the sample mass 0.1 mg.
Results
Differential scanning calorimetry is a technique in which the differences in energy impute into a
material and a reference material is measured as a function of temperature. Figure 1 shows the
DSC spectra of the KELTAN 4200. The curve indicates the glass transition temperature at -
54.170C and at 53.400C.
-0,8
-0,9
Heat flow, W/g
-1,0
-1,1
-1,2
-1,3
-100 -50 0 50 100 150
0
Temperature, C
.
Fig. 1 The DSC thermogram of a KELTAN 4200
100
B
C
80
Weight and deriv. weight
60
40
20
0 100 200 300 400 500 600 700

0
Temperature, C
Fig. 2 TG-DTA spectra of copolymer KELTAN 4200: B- weight-temperature, C- deriv. weight-

temperature
Thermic behaviour of two copolymers used as viscosity improvers for SAE 10W mineral oil 39
Figure 2 shows the TG and DTA thermogram of the KELTAN 4200. The mesurements are used
primarily to determine the composition and heat resistance. The figure indicate: the modified
weight in the temperature range 262-470oC; the temperature initial of a descomposition thermic
is 262,5oC; the modified weight with temperature: 262,5-402oC – 42,99%, 402-510oC –
54,85%, 510-600oC – 1,46% and rezidue – 0,42%. The DTA curve present of two maximum.
The DTA curve we two point of a inflexion, the one of 357,1 and the second 435,0oC and the
temperature final on a descomosition thermic is 510oC.
Figure 3 present thermogram DSC of a copolymer INFINEUM SV 260.
-1,3
-1,4
-1,5
Heat flow, W/g
-1,6
-1,7
-1,8
-1,9
-2,0
-100 -50 0 50 100 150

0
Temperature, C
Fig. 3. The DSC curve of a copolymer INFINEUM SV 260
The curve indicates the glass transition temperature at -50,190C. The figure 4 shows the TG and
DTA thermogram of the INFINEUM SV 260.
100
B
C
80
Weight and deriv. weight
60
40
20
0 100 200 300 400 500 600 700

0
Temperature, C
Fig. 4 The TG-DTA curves of a copolymer INFINEUM SV 260

40 Ioana Stanciu
The figure 4 indicate: the modified weight in the temperature range 238-470oC; the
temperature initial of a descomposition thermic is 238oC; the modified weight with
temperature: 238-320oC – 5,55%, 320-470oC – 90%, 470-600oC – 3,15% and rezidue – 1,59%.
The curve DTA present of one maximum, we one point of a inflexion, the one of 407,20 and
the temperature final on a descomosition thermic is 600oC.
Conclusions
The glass transition temperatures as well as their heat stabilities of the two copolymers are very
close, with KELTAN 4200 having a bit lower glass transition temperature and higher heat
resistance. Taking account of the functioning temperatures of engines, both copolymers are
convenient to be used as viscosity improvers.
References
1. JOHN DEAN A., -The Analytical Chemistry Handbook, New York. McGraw Hill, Inc., 1995, pp. 15.1-
15.5
2. PUNGO E., - A Practical Guide to Instrumental Analysis. Boca Raton, Florida, 1995, pag. 181
3. SKONG, DOUGLAS A, JAMES HOLLER F. and NIEMAN T., -Principles of Instrumental Analysis.
Fith Edition, New York, 1995, pag. 905
4.. VYAZOVKIN S., -Int. Rev. Phys. Chem., 19, 2000, pag. 45
5. VYAZOVKIN S, WEIGHT CH. A., -Thermochim Acta., 340-341, 1999, pag. 53
6. STANCIU I., LECA M.,- Materiale Plastice, 42, 2005, pag. 268
7. STANCIU I., LECA M.,- Materiale Plastice, 43, 2006, pag. 236
8. STANCIU I., LECA M., -Buletin UPG – Seia Tehnica, LIX, 1,2007,
Comportarea termicã a doi copolimeri utilizaţi ca modificatori de

viscozitate pentru uleiul SAE 10W
Rezumat
Calorimetria dinamică diferenţială a fost metoda ultilizată pentru determinarea temperaturilor de
vitrifiere ale copolmerilor(KELTAN 4200 – polietilenă-polipropilenă şi INFINEUM SV 260 – polizopren
stiren-hidrogenat) recomandaţi ca modificatori de viscozitate pentru uleiul SAE 10W. Din curbele TG şi
DTA a fost determinată rezistenţa termică a acestora.

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BULETINUL Vol.

Thermic Behaviour of two Copolymers used as

Universitatea Bucureşti, Bd. Regina Elisabeta 4-12, 030018, Bucureşti, România

The following copolymers were used as viscosity improvers: hydrogenated poly(isoprene-co-

0 100 200 300 400 500 600 700

Fig. 2 TG-DTA spectra of copolymer KELTAN 4200: B- weight-temperature, C- deriv. weight-

-100 -50 0 50 100 150

Fig. 3. The DSC curve of a copolymer INFINEUM SV 260

0 100 200 300 400 500 600 700

Fig. 4 The TG-DTA curves of a copolymer INFINEUM SV 260

Comportarea termicã a doi copolimeri utilizaţi ca modificatori de

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