effect of dpg on silinization

1

Bound rubber study of silica

Effect of DPG on Effect of DPG on SilanizationSilanization Chemistry Chemistry of Silica in Rubber Processing of Silica in Rubber Processing S. Mihara*1), R.N. Datta2), A.G. Talma2), W.K. Dierkes2)

and J.W.M Noordermeer2)

1) Yokohama Rubber Co., LTD 2-1 Oiwake, Hiratsuka, Kanagawa, Japan

2) University of Twente , Faculty of Engineering Technology,

Dept. of Elastomer Technology and Engineering

P.O. Box 217, 7500 AE Enschede , the Netherlands

VKRT meeting on December 11

2

1. Introduction1. Introduction

1,31,3--diphenylguanidine (DPG)diphenylguanidine (DPG)

ØØSecondary cure accelerator in silicaSecondary cure accelerator in silica--filled rubberfilled rubberØØInteraction with silica surfaceInteraction with silica surfaceØØToxic concernsToxic concernsØØNegative influence on metalNegative influence on metal--rubber adhesionrubber adhesion

NH

C

NH

NH

3

1. Introduction1. Introduction

OH OOSiSi OCOC22HH55HH55CC22OO

(CH(CH22))33

SSxx

OSi OH5C2O

(CH2)3

Sx

OSi OC2H5

(CH2)3

Sx

OH OH

SySz

SilaneSilane--RubberRubbercouplingcoupling

CrosslinkingCrosslinking reactionreaction

+ Other reactions+ Other reactions

How does DPG influence on these reactions ???How does DPG influence on these reactions ???

TESPTNH

C

NH

NH

SilanizationSilanization Silica

Typical reactions during rubber processingTypical reactions during rubber processing

Polymer

4

ObjectivesObjectives

UnderstandingUnderstanding1. Influence of DPG on 1. Influence of DPG on silanesilane chemistrychemistry

2. Role of DPG during rubber processing 2. Role of DPG during rubber processing

1.1. SilanizationSilanization kineticskinetics2.2. CrosslinkingCrosslinking reaction between model olefinsreaction between model olefins3.3. Change of sulfur distribution in TESPTChange of sulfur distribution in TESPT4.4. TESPTTESPT--model olefin reactionmodel olefin reaction5.5. DPGDPG--TESPT reactionTESPT reaction

5

2. Experimental2. ExperimentalMaterialsMaterials

Mixture 1 Mixture 2 Mixture 3 Mixture 4

n-decane 1.4600 1.4600 - -2,3-dimethyl-2-butene - - 0.4000 0.4000Silica 0.2000 0.2000TESPT 0.0200 0.0200 0.0320 0.0320DPG - 0.0040 - 0.0071

2,3-dimethyl-2-butene(TME)

n-decane

N-decane: (Aldrich) ; 2,3-dimehyl-2-butene: (Aldrich) ; 3-methyl-1-pentene: (Aldrich)Silica: Zeosil 1165MP (Rhodia Silices) ; TESPT: Si69 (Degussa)DPG: Perkacit DPG (Flexsys B.V)

(g)(g)

Silanization kinetics Crosslinking between model olefins

TESPT reaction with polymer or DPG

6

Model olefinTESPTDPGSilicaN2 flowMelt

Reaction MixturesReaction Mixtures Reaction Mixtures

Dip into oil bath at specified temperatureDip into oil bath at specified temperature

Cool down the reaction mixture with iceCool down the reaction mixture with ice

Filtration of reaction mixture using micro pore filter

Diethyleneglycol-monobutylether

treatment

HPLCHPLC HPLC and MSHPLC and MS

Sample preparationsSample preparations

1. Silanization kinetics 2. Cross-linking products3. TESPT-model olefin complex4. TESPT-DPG complex

7

HPLC conditions

Column Nucleosil 100-5 C18 HD Length of column 250 mmInternal diameter 4.6 mmMobile phaseMobile phase AcetonitrileAcetonitrile : water = 97 : 3: water = 97 : 3Flow rate 0.3 ml/minTemperature 23 CDetector UV (DAD)Wavelength 254 nm (200 to 700 nm)Injection volume 0.5 ml

S2S3

S4

S5S6 S7

Chromatographic and MS ConditionsChromatographic and MS Conditions

Chromatogram of TESPT (Mixture 1 or 2)Chromatogram of TESPT (Mixture 1 or 2)

MS ionization conditions in APCIAPCI

Flow rate 20 ml/minNebliser gas pressure 25 psiDry gas flow 3 L/minDry gas Temp. 320 CVaporise Temp. 425 C

238.9

266.9294.9

323.0

250 300 350

0

0.5

1.0

1.5

2.0

x105

Inte

nsity

[mA

U]

m/zMass to charge ratio

Retention time

Inte

nsity

APCI : Atmospheric Pressure Chemical Ionization

[ M + H] + is detected.

[ M + H] +[ M + H] +

8

Calculation of kinetic parametersCalculation of kinetic parameters

)t(C)t(C)t(Cx

0

10 −=

][mintt

)x1ln()x1ln(k 1

01

tt1

01 −−

−−−=

x is conversion of TESPT, C(t0) and C(t1) are the amounts of unun--reacted TESPTreacted TESPTat time t0 and t1, respectively, k1 is the rate constant of silanization.

RTE)kln(kln a

01 −=

ArrheniusArrhenius equationequation

Ea is the activation energy, R is the gas constant, R is the gas constant, T is the absolute temperature.T is the absolute temperature.

Summed peak = amount of un-reacted TESPT

S2S3

S4

S5S6 S7

1/T

lnk 1

Ea

9

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

0 2 4 6 8 10Time (min)

ln(1

-x)

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

0 2 4 6 8 10

ln(1

-x)

Time (min)

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

ln(1

-x)

0 2 4 6 8 10Time (min)

(a) 120 C (b) 140 C (c) 160 C

ØØIn the presence of DPGIn the presence of DPG conversion of TESPT conversion of TESPT increases fast at the beginning of reaction.increases fast at the beginning of reaction.

3.1 Influence of DPG on 3.1 Influence of DPG on SilanizationSilanization KineticsKineticsConversion of TESPTConversion of TESPT

with DPGwith DPG with DPGwith DPG with DPGwith DPG

without DPGwithout DPG without DPG

SiOC2H5

OC2H5

(CH2)3 S2H5C2O

OH

OH

Silica

+

TESPT

SiOC2H5

OOC2H5

(CH2)3 S2

OH2

10

Mixture 1Mixture 1 Mixture 2Mixture 2without DPGwithout DPG with DPGwith DPG

Rate constant kRate constant k11 (1/min)(1/min) 0.170.17 1.091.09Activation energy EActivation energy Eaa (kJ/mol) 29.3(kJ/mol) 29.3 11.011.0

ØØkk11 of increases by a factor of six.of increases by a factor of six.ØØEEaa decreases till one third.decreases till one third.

3.1 Influence of DPG on 3.1 Influence of DPG on SilanizationSilanization KineticsKineticsCalculated kinetic parametersCalculated kinetic parameters

DPG can accelerate the DPG can accelerate the silanizationsilanization reaction.reaction.

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3.2 Influence of DPG on 3.2 Influence of DPG on crosslinkingcrosslinking reaction reaction between model olefinsbetween model olefins

Time [min]

02.0

4.0

6.0

2018 22 24 26 28

3x10

S2*S2*S3*S3*

S4**S5**

S6** S7**

S4*S4*S5*S5* S6*S6*

S2**

S3**

Inte

nsity

[mA

U]

CH2

CH3CH3

CH3 Sx CH2

CH3 CH3

CH3

S.C. Debnath, R. N. Datta, J. W. M. Noordermeer, RUBBER CHEM. TECHNOL. 76, 1311 (2002).

CrossCross--linked product of TMElinked product of TME

** TESPT

2 + Sx

Coming from TESPT

DPGDPG

12

0

50000

100000

150000

200000

250000

300000

0 10 20 30 40Reaction time (min)

Peak

are

a [m

AU

]

without DPG

with DPGwith DPG

ØØThe total peak area of The total peak area of the crossthe cross--linked products increaseslinked products increases with with increasing reaction time, increasing reaction time, even in the absence of elemental sulfureven in the absence of elemental sulfur..ØØIn the presence of DPG the increase of the crossIn the presence of DPG the increase of the cross--linked products is linked products is

much faster compared to the DPGmuch faster compared to the DPG--free system. free system.

TESPT acts as a sulfur donor during processing.TESPT acts as a sulfur donor during processing.

3.2 Influence of DPG on 3.2 Influence of DPG on crosslinkingcrosslinking reaction reaction between model olefinsbetween model olefins

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Si

OC2H5

OC2H5

H5C2O (CH2)3 Sx (CH2)3 Si

OC2H5

OC2H5

OC2H5

In the presence of DPG the increase of the triIn the presence of DPG the increase of the tri--sulfide is sulfide is relatively faster compared to the DPGrelatively faster compared to the DPG--free system. free system.

0.0

0.2

0.4

0.6

0.8


Rat

io o

f sul

fur

rank

0.0

0.2

0.4

0.6

0.8


Rat

io o

f sul

fur

rank with DPGwith DPGwithout DPGwithout DPG

S3S3S3S3

3.3 Influence of DPG on sulfur distribution in TESPT3.3 Influence of DPG on sulfur distribution in TESPT

( ) : S3 ;( ) : S2 ; ( ) : S4 ; ( ) : S5 ; ( ) : S6 ; ( ) : S7

**Reaction Temperature : 140 Reaction Temperature : 140 CC

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3.4 Influence of DPG on reaction between3.4 Influence of DPG on reaction betweenTESPT and model olefinsTESPT and model olefins

12 14 16 180

1

2

3

4

5

0

12 14 16 18

1

2

3

4

5

0

0

1

2

3

0

12 14 16 180

2

4

6

0

Ion

inte

nsity

x 1

04 (m

AU

)

0 12 14 16 18Retention time (min)

(a)

(b)

(b)(c)

(d)

0 12 14 16 18

0

0 12 14 16 18

12 14 16 18 Time [min]12 14 16 18

0

1

2

3

4

5

0

1

2

3

4

5

0

1

2

3

4

5

0

1

2

3

4

5

( x 1

05 )

( x 1

05 )

( x 1

04 )

TMETME

TME+DPGTME+DPG

TME+TESPTTME+TESPT (Mixture 3)(Mixture 3)

TME+TESPTTME+TESPT+DPG (Mixture 4)+DPG (Mixture 4)

Reaction Temperature:140 ºCTime: 30 minutes

Extracted ion peak of 323 Extracted ion peak of 323 m/zm/z

Si

OC2H5

OC2H5

H5C2O (CH2)3 Sx+2

S

SiOC2H5

CH3

CH3CH

CH3

CH3

OC2H5

H5C2O

[M + H[M + H++] = 323 ] = 323 m/zm/z

15

Fragmentation of 323 Fragmentation of 323 m/zm/z using the MS using the MS

Masses of 295 Masses of 295 m/zm/z, 267 , 267 m/zm/z and 239 and 239 m/zm/z coming from coming from the TESPTthe TESPT--TME complex are obtained.TME complex are obtained.

This decrease with each time 28 This decrease with each time 28 m/zm/z can be related to progressive can be related to progressive hydrolysis of the hydrolysis of the ethoxyethoxy groups of the TESPT moiety. groups of the TESPT moiety.

238.9

266.9294.9

323.0

250 300 350

0

0.5

1.0

1.5

2.0

x105In

tens

ity [m

AU

]

Mass to charge ratio

[M + H+]


16

Possible structures of TESPTPossible structures of TESPT--Model Olefin ComplexModel Olefin Complex

S

SiOC2H5

CH3

CH3CH

CH3

CH3

OC2H5

H5C2O

S

Si

CH3

CH3CH

CH3

CH3

OHOC2H5

H5C2O

S

Si

CH3

CH3CH

CH3

CH3

OHOH

H5C2O

S

Si

CH3

CH3CH

CH3

CH3

OHOH

OH

M + H+ = 323

- C2H4

Hydrolysis- C2H4

Hydrolysis- C2H4

Hydrolysis

-28 m/z -28 m/z -28 m/z

M + H+ = 295 M + H+ = 267 M + H+ = 239


17


Amount of TESPTAmount of TESPT--Model Olefin ComplexModel Olefin Complex

ØØThe total peak area of TESPTThe total peak area of TESPT--Model olefin complexModel olefin complexincreases with increasing reaction time. increases with increasing reaction time. ØØDPG is capable of accelerating the TESPTDPG is capable of accelerating the TESPT--model olefin reaction.model olefin reaction.

0

2000000

4000000

6000000

8000000

10000000

12000000


Peak

are

a [m

AU

] with DPGwith DPG

without DPGwithout DPG

18

(a)

(b)

Inte

nsity

x 10

5[m

AU

]

14 16

Retention time [min]

00

1

2

3

4

5

14 160

0

1

2

3

4

5

Extracted ion chromatograms of 530 Extracted ion chromatograms of 530 m/zm/z

In the presence of DPG and TESPT In the presence of DPG and TESPT an extracted ion peak of 530 an extracted ion peak of 530 m/zm/z can be seen. can be seen.

3.5 Reaction of TESPT with DPG3.5 Reaction of TESPT with DPG

TME + TESPT (Mixture 3)TME + TESPT (Mixture 3)

TME + TME + TESPT + DPG TESPT + DPG (Mixture 4)(Mixture 4)

Reaction Temperature:140 ºCTime: 30 minutes

19

Inte

nsity

[mA

U]

(a)530

528 530 5320

1

2

x 102 (b)498.5

496 498 500

1

x 102 (c)466

464 466

1.0

1.2

454

x 102

Mass to charge ratio (m/z) Mass to charge ratio (m/z) Mass to charge ratio (m/z)

NH N

Sx

H5C2O

H5C2O

SiOC2H5

(a) X=4 Mw = 530 m/z(b) X=3 Mw = 498 m/z(c) X=2 Mw = 466 m/z

Fragments of TESPT Fragments of TESPT –– DPG complex due to elimination of sulfur DPG complex due to elimination of sulfur

A decrease with 32 A decrease with 32 m/zm/z each is observed, each is observed, corresponding to elimination of sulfur corresponding to elimination of sulfur atoms from DPGatoms from DPG--TESPT complex TESPT complex


-32 -32

20

The total peak area of the DPGThe total peak area of the DPG--TESPT complex slowly increases at the TESPT complex slowly increases at the beginning of the reaction and then increases very fast. beginning of the reaction and then increases very fast.


Mw=530 g/mol2

4

6

8

10

12

14

16

18

0 10 20 30 40

Reaction time (min)

Peak

are

a x

106

[mA

U]

0

21

Therefore, significant amounts of DPG could be consumed Therefore, significant amounts of DPG could be consumed during processing due to this mutual TESPTduring processing due to this mutual TESPT--DPG reaction.DPG reaction.

1. The 1. The silanizationsilanization reaction is promoted:reaction is promoted:

> Reaction Rate Constant of TESPT : Increasing by a factor of s> Reaction Rate Constant of TESPT : Increasing by a factor of sixix> Activation Energy> Activation Energy : Decreasing till one third: Decreasing till one third

2. The tri2. The tri--sulfide isomer in TESPT increases. sulfide isomer in TESPT increases. > This tri-sulfide can possibly act as a sulfur donor during processing.

4. TESPT can itself react with the model olefin or DPG.4. TESPT can itself react with the model olefin or DPG.

3. The amount of cross3. The amount of cross--linked products increases.linked products increases.

Due to the presence of DPG in reaction mixtureDue to the presence of DPG in reaction mixture……

4. Conclusions4. Conclusions

22

This project was financially supported by This project was financially supported by YOKOHAMA RUBBER CO., LTD. YOKOHAMA RUBBER CO., LTD.

Thank you for your attention.Thank you for your attention.

5. Acknowledgement5. Acknowledgement

effect of dpg on silinization

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