Relations between thermal degradations of SBS copolymer and asphalt substrate in polymer modified asphalt

ORIGINAL PAPER

Relations between thermal degradations of SBS copolymerand asphalt substrate in polymer modified asphalt

Motoyuki Sugano • Yuusuke Iwabuchi •

Tohru Watanabe • Jun Kajita • Kohji Iwata •

Katsumi Hirano

Received: 15 September 2009 / Accepted: 5 May 2010 / Published online: 20 May 2010

� Springer-Verlag 2010

Abstract The variations in the chemical characteristics

of asphalt constituents and styrene–butadiene–styrene tri-

block copolymer (SBS) in the polymer modified asphalt

(MA) during degradation process should be clarified to

design the effective recycle method of MA. In this study,

the chemical characteristics of MA during thermal degra-

dation process were studied in detail. The effects of the

period of thermal degradation of MA, the content of as-

phaltene constituent in MA and the kind of substrate

instead of the straight asphalt were discussed from the yield

and thermogravimetry (TG) curves of four constituents in

MA and the molecular weight distribution of SBS. As a

result, the yield of polar constituent (asphaltene) increased

gradually with decomposition of SBS during thermal

degradation of MA. Decomposition of SBS was enhanced

by the low molecular weight substrate, such as aromatic

oil. On the other hand, decomposition of SBS was inhibited

by MA of high asphaltene content.

Keywords Polymer modified asphalt �Thermal degradation �Styrene–butadiene–styrene triblock copolymer �Molecular weight distribution � Asphaltene

Abbreviations

Aromatics Fractions of toluene eluate from

glass column filled with

activated alumna

Asphaltene n-hexane insoluble material

fa Aromaticity index of the unit

structure of a constituent in

asphalts

GPC Gel permeation chromatography

Haus/Caus Index of condensed aromatic

ring of the unit structure of a

constituent in asphalts

MA Polymer modified asphalt

Maltene n-hexane soluble material

MAA, MAB and MAC Three kinds of polymer

modified asphalt

MO Polymer modified aromatic oil

MOR Polymer modified aromatic oil

and industrial resin

Resins Fractions of methanol ?

toluene ? methanol eluate from

glass column filled with

activated alumna

SA Straight asphalt

SAA, SAB and SAC Three kinds of straight asphalt

Saturates Fractions of n-hexane eluate

from glass column filled with

activated alumna

SBS Styrene–butadiene–styrene

triblock copolymer

TG Thermogravimetry

TG/DTA Thermogravimetry/differential

thermal analysis

THF Tetrahydrofuran

M. Sugano (&) � Y. Iwabuchi � T. Watanabe � J. Kajita �K. Iwata � K. Hirano

Department of Materials and Applied Chemistry, College of

Science and Technology, Nihon University, 1-5, Kanda

Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan

e-mail: [email protected]

123

Clean Techn Environ Policy (2010) 12:653–659

DOI 10.1007/s10098-010-0301-9

Introduction

It is well known that the polymer modified asphalt (MA)

has superior properties, such as fluidity-resistant, abrasion-

resistant and draining property, as binder in the pavement.

Therefore, the output of MA increases every year and

exceeds 430 kt per year in Japan. In Japan, asphalt pave-

ment makes up 90% of paved road. In Tokyo, MA pave-

ment makes up 80% of the asphalt paved road. In Japan,

about 85% of MA was produced by modification of straight

asphalt (SA) with styrene–butadiene–styrene triblock

copolymer (SBS). On the other hand, recycling and

lengthening of life of MA are required because recycling of

pavement materials is obligatory by law in Japan. The

blending of recovered materials from the transportation

sector or secondary or by-product materials from the

industrial, municipal, or mining sector into asphalt was

estimated (Apul et al. 2003).

In order to establish the recycle process and lengthen the

life of MA, the degradation mechanism of MA must be

clarified. It was clarified that the rheological properties of

the aged polymer modified bitumen were dependent on a

combined effect of bitumen oxidation and SBS degradation

(Lu and Isacsson 1998, 2000). During the ageing of MA, the

relation between thermal degradation of SBS and the

physical and rheological properties of MA was discussed

(Cortizo et al. 2004). During the oxidative ageing of MA, it

was revealed that the changes in the chemical structures of

several kinds of polymer modifiers affected the degradation

of asphalt constituent in MA (Ruan et al. 2003a, 2003b).

They also discussed the changes in the rheological proper-

ties of several kinds of MA during the long-term

(2–18 months) oxidation (Ruan et al. 2003b. From the

results of dynamic shear rheometry, ductility, force ductility

and gel permeation chromatography of MA during oxida-

tive ageing, the primary cause of MA degradation was

considered as the base asphalt embrittlement rather than

polymer degradation (Woo et al. 2007). Thermal oxidation

process of SBS was studied by thermal analysis, dynamic

mechanical analysis and FTIR spectroscopy (Li et al. 2010).

However, the degradation mechanism of MA has not

been fully reported from the variation on the chemical

properties of MA. Therefore, in this study, thermal degra-

dation mechanism of MA was discussed from the molec-

ular weight distribution of SBS, thermogravimetry and the

yields of four constituents separated by solvent extraction.

Further, in an attempt to clarify the property of substrate

which decomposes SBS, the degradation behaviours of the

polymer modified samples of aromatic oil and industrial

resin were also investigated in this study. Moreover, the

effect of the difference in the yield of four constituents in

raw SA was also discussed from thermal degradation of

two kinds of MA.

Experimental part

Sample preparation and thermal degradation of samples

Three kinds of SA, such as SAA, SAB and SAC, were used

in this study. The experimental scheme for preparation and

degradation processes of MA is summarized in Fig. 1.

Three kinds of MA, such as MAA, MAB and MAC, were

prepared by mixing SBS and the corresponding SA

(SBS:SA = 1:9) at 190�C for 6 h. The thermal degraded

samples of MAA were prepared by heating MAA at 190�C

for 5 and 12 days, respectively. The thermal degraded

samples of SA, MAB and MAC were prepared as same as

MAA. The experimental scheme for preparation processes

described below is summarized in Fig. 2. The polymer

modified aromatic oil (MO) was prepared by mixing SBS

and the aromatic oil (SBS:aromatic oil = 1:9) at 190�C for

6 h. The polymer modified aromatic oil and industrial resin

(MOR) was prepared by mixing SBS, the industrial resin

and the aromatic oil (SBS:industrial resin:aromatic oil =

1:2:7) at 190�C for 6 h.

Separation of samples into four constituents

The experimental scheme for separation of samples into

four constituents is summarized in Fig. 3. After each

sample was extracted with n-hexane under an ultrasonic

irradiation, the slurry was filtered to separate residue and

filtrate. The n-hexane insoluble (asphaltene) material was

prepared from the residue by drying for 3 h under vacuum

at 60�C. On the other hand, after n-hexane was evaporated

from the filtrate, the n-hexane soluble (maltene) material

was prepared by drying the extract for 3 h under vacuum at

60�C. After each maltene was placed at the top of activated

alumna (75 g) filled in the glass column with n-hexane,

300 ml of n-hexane, 300 ml of toluene and 260 ml of

mixture of methanol and toluene (80 ml of methanol,

Straight asphalt (SA)SAA, SAB, SAC

Straight asphalt (SA)SAA, SAB, SAC

SA: SBS = 9:1Mixing at 190 OC for 6 h

Styrene-butadiene-styrene triblock copolymer (SBS)

Styrene-butadiene-styrene triblock copolymer (SBS)

Polymer modified asphalt (MA)MAA, MAB, MAC

Polymer modified asphalt (MA)MAA, MAB, MAC

Heating at 190 OC for 5 or 12 days

Thermal degraded samples Thermal degraded samples

Fig. 1 Experimental scheme for preparation and degradation pro-

cesses of MA

654 M. Sugano et al.

123

80 ml of toluene and 100 ml of methanol) were succes-

sively flowed into the glass column. After each eluate was

obtained, each fraction was obtained by solvent evapora-

tion from the eluate. The fractions from the eluates of

n-hexane, toluene and methanol ? toluene ? methanol

were referred as saturates, aromatics and resins.

Gel permeation chromatography (GPC)

The GPC system used was a Shimadzu LC-10ADVP pump

equipped with a Shimadzu SPD-10ADVP UV–VIS spec-

trometer and two GPC columns, Shimadzu GPC-805 and

GPC-804. In the analysis, 1 mg of sample in 1 ml of tet-

rahydrofuran (THF) solution was prepared and 20 ll of

sample solution was injected into the column at 40�C. The

rate of the THF mobile phase was fixed at 1 ml/min.

Thermogravimetry (TG)

A TG curve of each sample was measured with thermo-

gravimetry/differential thermal analysis (TG/DTA) instru-

ment (Shimadzu, DTG-50). A weighed sample (2 mg) was

heated at the rate of 20�C/min up to 600�C in a nitrogen

atmosphere (Sugano et al. 2007).

Measurement of 1H-NMR spectra

The 1H-NMR spectra of SAA and its four constituents were

measured as a CDCl3 solution with a JEOL JNM-EX90A

(90 MHz, FT mode) spectrometer (Sugano et al. 2006).

Discussion of the results

Effects of polymer modification of asphalt on thermal

degradation

The ultimate analyses and the average structural parame-

ters of SAA and its four constituents are given in Table 1.

The aromaticity index (fa) and the index of condensed

aromatic ring (Haus/Caus) of the unit structure of SAA and

its four constituents were calculated from the ultimate

analysis and the hydrogen distribution of an 1H-NMR

spectrum of the constituent according to the Brown and

Ladner method (Brown and Ladner 1960). The values of fa

and the content of hetero atom increased in the order:

saturates \ aromatics \ resins \ asphaltene. The values

of Haus/Caus and H/C decreased in the order: satu-

rates [ aromatics [ resins [ asphaltene. Therefore, it was

confirmed that the constituent of saturates consisted of

alkanes and aromatics attached to the long-chain alkyl

groups. On the other hand, the constituent of asphaltene

consisted of polynuclear aromatic compounds, which

contained hetero atom and/or attached to the oxygen-con-

taining functional groups.

The yields and the amounts of average molecular weight

of four constituents after thermal degradation of SAA and

MAA are shown in Figs. 4 and 5, respectively. From

Fig. 4, over 99% of SBS was classified into asphaltene

constituent. The yield of MAA (Calc.) in Fig. 4 indicates

an arithmetic mean value using the yields of SAA and SBS,

which means the yield of mixture of SAA and SBS (9:1)

without thermal degradation. Compared with the calculated

yield of MAA, the yield of asphaltene increased slightly

since thermal degradation between SAA and SBS occurred

during preparation of MAA with heat. With the increase of

period of thermal degradation of MAA, the increase of

asphaltene yield and the decrease of aromatics yield were

observed as same as thermal degradation of SAA. From

Fig. 5, the molecular weight of asphaltene increased during

thermal degradation of SAA; however, the value did not

change during thermal degradation of MAA. Therefore, it

was estimated that polymerization of molecules of

asphaltene in MAA was inhibited by SBS.

The variation in molecular weight (GPC profile) of SBS

during thermal degradation of MAA was shown in Fig. 6.

The height ratio of two peaks (200,000 and 100,000) of

molecular weight was 1:0.26 for the raw SBS. However, the

Aromatic oilAromatic oil

SBS: Aromatic oil = 1:9Mixing at 190 OC for 6 h

SBSSBS

Polymer modified aromatic oil (MO)Polymer modified aromatic oil (MO)

Industrial resin Industrial resin

Polymer modified aromatic oil and industrial resin (MOR)

Polymer modified aromatic oil and industrial resin (MOR)

SBS: Aromatic oil: industrial resin= 1:7:2Mixing at 190 OC for 6 h

Fig. 2 Experimental scheme for preparation processes of MO and

MOR

Insoluble

n-Hexane extraction

AsphalteneAsphaltene

Soluble

MalteneMaltene

n-Hexane eluate

SaturatesSaturates

Asphalt sampleAsphalt sample

Liquid chromatography

Toluene eluate

AromaticsAromatics

ResinsResins

Methanol and toluene eluate

Fig. 3 Experimental scheme for separation of samples into four

constituents

Thermal degradations of polymer modified asphalt 655

123

peak height of 100,000 increased during thermal degrada-

tion of MAA. Therefore, SBS in MAA decomposed to the

low molecular weight molecules with the increase of period

of thermal degradation of MAA. The TG curves of four

constituents from SAA are shown in Fig. 7. Decomposition

extent of four constituents increased in the order: asphal-

tene \ resins \ aromatics \ saturates. Therefore, during

thermal degradation of MAA, radicals formed from

decomposition of SBS were stabilized with radicals formed

from constituents in maltene, which decomposed at rela-

tively lower temperature. With the increase of period of

thermal degradation of MAA, the yield of asphaltene

increased; however, the molecular weight of asphaltene did

not change as shown in Figs. 4 and 5 because SBS, which

classified in asphaltene, combined with radicals from mal-

tene and the combined maltene constituent was contained in

asphaltene. Therefore, it was considered that polymeriza-

tion of molecules of asphaltene in MA was inhibited by

decomposition of SBS. Accordingly, during thermal deg-

radation of MAA, MAA degraded by the decrease of mal-

tene yield and decomposition of SBS.

The molecular weight distribution (GPC profile) of four

constituents and the yields of SBS classified to four con-

stituents after thermal degradation of MAA are shown in

Figs. 8 and 9, respectively. The peak area ascribed to SBS

ranged from 8.0 min. to 10.0 min. of the retention time in

Fig. 8. The yields of SBS in Fig. 9 were calculated from

the proportion of peak area in each constituent ascribed to

SBS. On preparation of MAA, half of SBS was contained

in asphaltene constituent as shown in Fig. 9. With the

increase of period of thermal degradation of MAA, the

Table 1 Ultimate analyses and the average structural parameters of SAA and its four constituents

Ultimate analyses (wt%, dry basis) Structural parameters

C H N S ? Oa H/C fa Haus/Caus

Straight asphalt 84.9 10.1 0.6 4.4 1.43

Saturates 86.4 11.9 0.0 1.7 1.65 0.18 0.16

Aromatics 84.9 10.4 0.3 4.4 1.46 0.32 0.66

Resins 84.0 9.2 1.1 5.7 1.32 0.40 0.58

Asphaltene 83.7 7.7 1.2 7.4 1.11 0.52 0.51

a By difference

0 10 20 30 40 50 60 70 80 90 100

Yield (wt% dry basis)

Aromatics setarutaSenetlahpsA Resins

SAA

5 days

12 days

6 hours

MAA (Calc.)

5 days

12 days

SBS

MAA (Obs.)

Fig. 4 Yields of four constituents after thermal degradation of SAA

and MAA

0

2000

4000

6000

Asphaltene Resins Aromatics Saturates

Ave

rag

e m

ole

cula

r w

eig

ht

12 days5 daysSA 6 hours

0

2000

4000

6000

The molecular weight distribution of SBS was not included.

The molecular weight distribution of SBS was not included.

MAA 12 days5 daysSA

(a) SAASAA(a)

(b)(b) MAAMAA

Fig. 5 Average molecular weight of four constituents after thermal

degradation of a SAA and b MAA UV

abso

rban

ce (

mA

bs)

Molecular weightHigh Low

Retention time (min.)

Peak derived from asphalt

Peak derived from asphalt

MAA

5 days

12 days

MW (x 104): 2.0 1.0Height ratio of peaks

MAA 1 0.725 days 1 1.40

Raw SBS 1 0.26

12 days

Peak derived from SBSPeak derived from SBS

0

10

20

30

40

50

10 12 14 16 18 20 22 24

Fig. 6 Molecular weight distributions (GPC profiles) of SBS after

thermal degradation of MAA


123

content of SBS in resins constituent increased in compen-

sation for the decrease of SBS in asphaltene constituent. As

written above, during thermal degradation of MAA, radi-

cals formed from decomposition of SBS were stabilized

with the easily formed radicals formed from maltene con-

stituents. Therefore, it was considered that the stabilized

molecules formed from SBS and maltene constituents were

mainly contained in both asphaltene and resins constitu-

ents. Further, during thermal degradation of MAA, it was

anticipated that the amount of stabilized molecules in

resins constituent increased with the progress of decom-

position of SBS.

Effects of molecular weight of substrate

on decomposition of SBS

The yields of four constituents and the TG curves of three

kinds of substrates are shown in Figs. 10 and 11, respec-

tively. From Fig. 10, the yields of asphaltene and resins in

the industrial resin were larger than those in the aromatic

oil. The values of average molecular weight of aromatic

oil, industrial resin and SA are 925, 966 and 1036,

respectively. From Fig. 11, decomposition extent increased

in the order: aromatic oil [ industrial resin [ SA.

The variation in molecular weight of SBS during ther-

mal degradation of MAA, MO and MOR was shown in

Fig. 12. During preparation of MO, SBS in aromatic oil

decomposed to the low molecular weight molecules sig-

nificantly. Although SBS in aromatic oil and industrial

resin decomposed to the low molecular weight molecules

during preparation of MOR, the decreasing amount of

molecular weight of SBS in both aromatic oil and industrial

resin was lower than that in aromatic oil only. However,

SBS in MOR also decomposed to the low molecular weight

molecules during thermal degradation. On the other hand,

SBS in SA did not decompose to the low molecular weight

molecules during preparation of MAA and decomposed

gradually to the low molecular weight molecules during

thermal degradation. Therefore, decomposition of SBS in

0

20

40

60

80

100

0 100 200 300 400 500 600

Asphaltene

Resins

Aromatics

Saturates

Wei

gh

t (%

)

Temperature (°C)

Fig. 7 TG curves of four constituents from SAA

UV

ab

sorb

ance

(m

Ab

s)



Asphaltene

Resins

Aromatics

Saturates0

10

20

7 8 9 10 11 12

MW (x 104)2.0 1.0

Fig. 8 Molecular weight distributions (GPC profiles) of four constit-

uents after thermal degradation of MAA

0 10 20 30 40 50 60 70 80 90 100

MAA

Yield (% SBS basis)

5 days

12 days


Fig. 9 Yields of SBS classified to four constituents after thermal

degradation of MAA

0 10 20 30 40 50 60 70 80 90 100

Aromatic oil


Industrial resin

Straight asphalt


Fig. 10 Yields of four constituents of three kinds of substrates

0

20

40

60

80

100

0 100 200 300 400 500 600

Wei

gh

t (%

)

Temperature (°C)

Industrial resin

Straight asphalt

Aromatic oil

Fig. 11 TG curves of three kinds of substrates


123

aromatic oil was considered to be enhanced by the radicals

from aromatic oil because decomposition extent of the

aromatic oil was higher than that of the industrial resin and

SA as shown in Fig. 11. However, decomposition of SBS

was expected to be suppressed by the addition of the

industrial resin since decomposition extent of the industrial

resin was lower than that of the aromatic oil. On the other

hand, it was anticipated that decomposition of SBS in SA

was suppressed remarkably because decomposition extent

of SA was lower than that of the aromatic oil and the

industrial resin. Further, the high molecular weight mole-

cules, such as asphaltene, were contained in SA. Accord-

ingly, it was clarified that decomposition of SBS was

enhanced in the substrate consisted of low molecular

weight molecules.

Effects of properties of asphalt substrate

on decomposition of SBS during thermal

degradation of two kinds of MA

The yields with the amounts of average molecular weight

of four constituents and the TG curves of four constituents

in two kinds of SA, such as SAB and SAC, are shown in

Figs. 13 and 14, respectively. From Fig. 13, the yields and

the average molecular weight of asphaltene in SAB were

larger than those in SAC. The values of average molecular

weight of resins in SAB were also larger than that in SAC.

From Fig. 14, decomposition extent of four constituents in

SAB was lower than that in SAC, which was consistent

with the higher yields and the higher molecular weight of

asphaltene and resins in Fig. 13.

The yields of four constituents and the variation in

molecular weight (GPC profile) of SBS after thermal

degradation of MAB and MAC are shown in Figs. 15 and

16, respectively. From Fig. 15, the yield of asphaltene in

MAB was higher than that in MAC, which was consistent

with the yields of asphaltene in SAB and SAC (Fig. 13).

However, with the increase of period of thermal degrada-

tion, the increasing yield of asphaltene in MAB was lower

than that in MAC. From Fig. 16, during thermal degrada-

tion of MAB and MAC, the peak height of 100,000

increased as well as MAA in Fig. 6. However, the

increasing amount of the peak height ratio on thermal

degradation of MAC was higher than that of MAB. In other

words, compared with SBS in MAB, decomposition of

SBS to the low molecular weight molecules was enhanced

in MAC. These results were consistent with the discussion

that decomposition of SBS was enhanced by the substrate

consisted of low molecular weight molecules as written in

the preceding paragraph. Therefore, decomposition of SBS

was considered to be enhanced in MAC because the yield

and molecular weight of asphaltene in MAC were lower

than those in MAB. Accordingly, it was clarified that

decomposition of SBS was enhanced by the asphalt sub-

stance of high maltene yield, which decomposed at rela-

tively lower temperature.

0

5

10

15

20

25

SBS

Thermal mixing

Mo

lecu

lar

wei

gh

t o

f S

BS

(X

104 )

1 2 3

Thermal degradation

MAA

MORMO

Fig. 12 Variations in molecular weight of SBS during thermal

degradation of MAA, MO and MOR

0 10 20 30 40 50 60 70 80 90 100

2418 1271 972 1024

1552 945 892 1149

SAB

SAC


Aromatics SaturatesAsphaltene Resins

Fig. 13 Yields of four constituents of two kinds of SA

0

20

40

60

80

100

0 100 200 300 400 500 600

300 °C

Asphaltene

Resins

Aromatics

Saturates

Wei

gh

t (%

)

Temperature (°C)

0 100 200 300 400 500 600

Temperature (°C)

SAB

(a)

(b)

0

20

40

60

80

100

240 °C

Asphaltene

Resins

Aromatics

Saturates

Wei

gh

t (%

)

SAC

Fig. 14 TG curves of four constituents in a SAB and b SAC


123

Conclusions

During thermal degradation of MA, MA degrades by

decreases of maltene yield and decomposition of SBS.

Relations between thermal degradations of SBS copolymer

and asphalt substrate in MA were concluded as below.

(1) Polymerization of molecules in asphaltene is inhib-

ited by decomposition of SBS.

(2) Decomposition of SBS was enhanced by the substrate

consisted of relatively low molecular weight

molecules.

(3) Decomposition of SBS was enhanced by the asphalt

substance of high maltene yield, which decomposed

at relatively lower temperature.

(4) The decomposed SBS radicals are stabilized with the

easily formed radicals derived from maltene, which

increases SBS in resins.

References

Apul DS, Gardner KH, Eighmy TT (2003) A probabilistic source

assessment framework for leaching from secondary materials in

highway applications. Clean Techn Environ Policy 5:120–127

Brown JK, Ladner WR (1960) Hydrogen distribution in coal-like

materials by high-resolution nuclear magnetic resonance spec-

troscopy. II. Fuel 39:87–96

Cortizo MS, Larsen DO, Bianchetto H, Alessandrini JL (2004) Effect

of the thermal degradation of SBS copolymers during the ageing

of modified asphalts. Polym Degrad Stab 86:275–282

Li Y, Li L, Zhang Y, Zhao S, Xie L, Yao S (2010) Improving the

aging resistance of styrene-butadiene-styrene tri-block copoly-

mer and application in polymer-modified asphalt. J Appl Polym

Sci 116:754–761

Lu X, Isacsson U (1998) Chemical and rheological evaluation of

ageing properties of SBS polymer modified bitumens. Fuel

77:961–972

Lu X, Isacsson U (2000) Artificial aging of polymer modified

bitumens. J Appl Polym Sci 76:1811–1824

Ruan Y, Davison RR, Glover CJ (2003a) Oxidation and viscosity

hardening of polymer-modified asphalts. Energy Fuels 17:991–

998

Ruan Y, Davison RR, Glover CJ (2003b) The effect of long-term

oxidation on the rheological properties of polymer modified

asphalts. Fuel 82:1763–1773

Sugano M, Onda D, Mashimo K (2006) Additive effect of waste tire

on the hydrogenolysis reaction of coal liquefaction residue.

Energy Fuels 20:2713–2716

Sugano M, Shimodaira K, Hirano K, Mashimo K (2007) Additive

effect of cobalt-exchanged coal on the liquefaction of subbitu-

minous coal. Fuel 86:2071–2075

Woo WJ, Hilbrich JM, Glover CJ (2007) Loss of polymer-modified

binder durability with oxidative aging: base binder stiffening

versus polymer degradation. Transp Res Rec 1998:38–46

0 10 20 30 40 50 60 70 80 90 100

MAB


5 days

12 days

MAC

5 days

12 days

Aromatics SaturatesAsphaltene Resins

Fig. 15 Yields of four constituents after thermal degradation of MAB

and MAC

UV

ab

sorb

ance

(m

Ab

s)

MW (x 104): 2.0 1.0

Height ratio of peaks

MAB 1 0.52

5 days 1 1.21

Raw SBS 1 0.26

12 days MAB

5 days

12 days

(a) MABMAB

0

5

10(a)

(b)

10 12 14 16 18 20 22 24

UV

ab

sorb

ance

(m

Ab

s)



MW (x 104): 2.0 1.0

Height ratio of peaks

Raw SBS 1 0.26

MAC

5 days

12 days

MAC 1 0.78

5 days 1 1.43

12 days

(b) MACMAC

0

5

10

10 12 14 16 18 20 22 24

Fig. 16 Variations in molecular weight (GPC profiles) of SBS after

thermal degradation of MAB and MAC


123

Documents

Relations between thermal degradations of SBS copolymer and asphalt substrate in polymer modified asphalt