STRUC
1 University o Netherlands 2 Apollo Tyre Abstract The elastome over a relativ silica-silane reduction of e.g. the num between fille microstructur rolling resist the propertie decrease the elevated tem cannot chem effect of spe indicators fo material. Keywords: S Introduction Thanks to improved w passenger c produced by element in t silane, which The chemic polymer-fille influence we Experiment The silane co to different fu A. Alk B. Sulf C. Link com The basic re used in this mentioned p similar to th reference sila ProceedingsCTURAL
DYNAM
E. Cich of Twente, Dep s es Global R&D er compound vely broad rancoupling age the rolling re mber of alkoxy er and polym re of the silic ance of a tire es of the comp hysteresis at h mperatures, thu mically link to ecific change or tire perform Silane couplin n a reduced r wet skid resist
cars are now y the use of
this technolog h chemically c al structure er interaction et skid and roll
al oupling agent functionalities koxysilane: cou fur-moiety: co ker: hydroc mpatibility wit quirement for study was t arts is modifi he reference ane is shown o
of the Polymer Pro
INFLUE
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omski1, T.V. T
ept. of Elastom D B.V., Colos
used for tire nge by modif ent system, fo sistance when y groups react mer, or the b ca-polymer int tread. It was posites. Silane high temperat us a lower ene the polymer, s in the struc mance will be ng agent, TESP rolling resista tance (WSR) wadays almo silica techno gy is the co couples silica of a silane ns, which ling resistance comprises th : upling to the s oupling to the carbon grou th the polymer r the variation that only one ied, while the silane. The s on the Figure ocessing Society 29th
ENCES O
PERTIES
Tolpekina2, S mer Technolog sseum 2, 7521 treads is a co fication of the or instance a n applied for t tive towards s bond strength terface and de shown that th es with just o tures and incre ergy loss at th the dynamic cture of the s e discussed, b PT, tire tread, ance (RR) a , tire treads ost exclusive ology. The k upling agent, to the polym determines t on their tu e.ree parts relat silica polymer up for bet r ns of the silan e of the abov e other parts a structure of t 1. th Annual Meeting ~
F SILAN
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. Schultz2, W. gy and Engine 1 PT Enschede omposite mate e polymer-fill allows reducin tire treads. Se silanol groups h between co etermine the d hese changes i one ethoxy groease it at low he service tem as well as the silane couplin besides the in , SBR and of ely key , a mer. the urn ted tter nes ve-are the In m di In re le th Th 2. bi ~ PPS-29 ~ July
15-NE COUP
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.K. Dierkes1, J eering, P.O. B e, the Netherla erial of which er interaction ng the hyster lective change s on the surfa upling agent dynamic prop in the silane st oup instead of temperatures mperature of a e mechanical ng agent on t nfluence on m Figure 1: Str (bis-(trietho n order to in modifications o ifferent silane n the first silan eplaced by in eads to a situat he silica surfa he structure o . is-(dimethylet Si O O O A -19, 2013, NurembeLING AG
ICA COM
J.W.M. Noord ox 217, 7500 A ands the dynamic . The replacem resis of the r es in the struc ace of the filleand polymer erties of the m tructure lead t f three as in t . A longer link a running tire. properties de the macroscop mechanical pro ucture of the r oxysilylpropy nvestigate the on wet skid an s were synthe ne modificatio nert methyl g tion in which ce on each si of this couplin Figure 2: St thoxysilylprop S S B C erg (Germany)
GENTS O
MPOUND
dermeer1 AE Enschede properties ca ment of carbo rubber, which cture of the co er, the length r, lead to ch material, thus to characterist the commonly ker lowers the When the sil eteriorate. In t opic dynamic operties of th reference cou yl) tetrasulfide e influence o and rolling res etized.on, two ethoxy groups. This only one grou ide of the sila ng agent is sho tructure of pyl) tetrasulfid S S C
ON THE
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, the an be adjusted on black by a h results in a oupling agent, h of the linker hanges in the s wet grip and tic changes in y used silanes e hysteresis at lane molecule this paper, the properties as he elastomeric pling agent (TESPT) of the silane sistance, three y groups were modification up can bind to ane molecule. own in Figure de (DMeSPT) Si O O O A d a a , r e d n s t e e s c e e e n o . e )back to S11 - oral presentations
Sulfur atoms second silan interactions w bi In the third s linker was modification of the silica chain in the polymer shou bis-(triet All silanes concentration with sulfur silica Zeosil tire recipe wa Methods Rolling resis the tanδ valu Rubber Proce The wet skid coefficient o 100), see Fig Figure 5 The side fo samples are obtained for referred as a rating is alwa Proceedings s were elimina ne (Figure 3 were limited t Figure 3: s-(triethoxysil ilane (Figure increased fr n should result a surface due molecule, but uld remain un Figure 4: thoxysilyldecy s were ap ns equimolar adjustment. A 1165 MP acc as used [1] . stance was as ue at 60°C an ess Analyzer d resistance w on a Laborat g. 5 [3]. 5. Measuring p orce coefficien e compared the sample co a rating. The ays better.
of the Polymer Pro
ated from the 3), hence the to physical int Structure of lyl)hexane (TE 4), the length rom propyl t in a better hy e to the long t the chemical nchanged. Structure of yl) tetrasulfide pplied at to the refere A test compo cording to the ssessed by m nd 6 % strain, (RPA 2000) [2 was measured a tory Abrasion principle of th nt values for with the r ontaining 7 ph given prope ocessing Society 29th molecule of t e polymer-fil teractions. ESH) h of the alipha to decyl. Th ydrophobisati ger hydrocarb l bonding to t e (TESDeT) four differe ence silane a ound containi Michelin gre measurements , measured on 2]
as the side for n Tester (LA
he LAT100 r the particu reference val hr of TESPT a erty with high
th Annual Meeting ~ the ller atic his ion bon the ent and ing een of n a rce AT ular lue and her R Bi Fo in hy et re su TE si su in gr co bo st w F a A ro re fo D re is co Rating (%) Rating (%) ~ PPS-29 ~ July 15-Results and Di is-(dimethylet or TESPT, we ndependent ypothesis aris thoxy groups eactivity of t urface is lim ESPT causes lane molecul urface. Howev ncreasing con roups on the ovalent bonds onds between rengthening o wet skid and ro
Figure 6: The c and side force
resistance f A concentration olling resistan eference samp ound that a DMeSPT up to esistance anym shown in Fig Figure 7: Diff of rolling resi and mono ompounds. Th TESPT 7 DMe 5 95 96 97 98 99 100 101 102 103 104 Rating (%) 0 20 40 60 80 100 120 Rating (%) -19, 2013, Nurembe iscussion thoxysilylpropy et skid and ro on concent ses: due to t connected t the TESPT mited. An in saturation of les, which ar ver, because o ncentration of e silica surfa with the poly n silica surfac of the interph olling resistanc correlation bet coefficient as for DMeSPT a compo n of 8.5 phr m nce up to 10 ple containing further incre o 10.4 phr do more. The ratin gure 7.
ferences in tan istance for the ethoxysilane ( he number ind phr eSPT 5 TESPT 9.5 DMeSPT 7 Wet skid resi 100 Tanδ at 60°C TESPT 7 erg (Germany) pyl) tetrasulfid olling resistan tration. The the three rela to the silicon molecule wi ncreased conc the surface w re weakly bo of less steric h f DMeSPT, ace can be u ymer. Increase ce and polym hase and imp ce. tween silane c s an indication and TESPT co ounds monoethoxysil 0% in compa g 7 phr of TE ease in con oes not improv
ing of the roll
n δ values as m e triethoxysila
(DMeSPT) co dicates the con
r. T TESPT 12 DMeSPT 8.5 TE 14 sistance at 8 °C 110 C, 10 Hz/6% strai DMeSPT 8 .5 de(DMeSPT)
nce are almost e following atively bulky ne atom, the th the silica centration of with unreacted onded to the indrance with more silanol used to form ed number of mer cause the provement of
concentration n for wet skid
ontaining lane improves arison to the ESPT. It was centration of ve the rolling ing resistance measurement ne (TESPT) ontaining ncentration in ESPT 4.4 DMeSPT 10.4 in t g y e a f d e h l m f e f s e s f g e
back to S11 - oral presentations
Proceedings of the Polymer Processing Society 29th Annual Meeting ~ PPS-29 ~ July 15-19, 2013, Nuremberg (Germany)
Bis-(triethoxysilyl)hexane(TESH)
Lack of chemical coupling of the filler to the polymer results in a drop in wet skid as well as rolling resistance (Figures 8 and 9). A filler that is weakly connected to the polymer causes sliding of the polymer on its surface during loading-unloading cycles, increasing the energy lost during rolling, and does not act like a reinforcing filler during wet skidding. Therefore simple hydrophobization of the silica surface without chemical filler-polymer bonding is not sufficient for obtaining good wet skid and rolling resistance.
Figure 8: Differences in side force coefficient for different loadings of the TESH and TESPT as
indication for wet skid resistance
Figure 9: Differences in tan δ values as indication of rolling resistance of the samples containing 5.3 phr of
TESH and 7 phr of TESPT
Bis-(triethoxysilyldecyl) tetrasulfide, (TESDeT)
Increasing the length of the aliphatic linker from 3 to 10 carbon atoms does not change the wet skid performance (Figure 10). However it cause substantial drop in rolling resistance as shown in Figure 11
Figure 10: Side force coefficient as measurement of the wet skid resistance versus concentration of TESDeT
and TESPT
Figure 11: Tan δ as measurement of rolling resistance of the samples containing TESDeT and TESPT At low deformation frequencies, typical for a rolling tire, the long linker acts like a “jelly” shell around the silica particles partially freeing them in the polymer matrix, and the polymer network can transfer energy more efficiently. At high deformation frequencies, the long linker in not able to follow the deformation, increasing the apparent viscosity. The silica particles are acting like a reinforcing filler again.
Conclusions
Using just one ethoxy group instead of three in the silane group of the coupling agent improves both, wet skid and rolling resistance.
Wet skid and rolling resistance deteriorate when sulfur is completely eliminated from the silane molecule, as do mechanical properties.
An increased linker length is expected to reduce rolling resistance by 15%, but does not change wet skid resistance.
In general, the stronger the interaction between the silica surface and the polymer, the better are both, wet skid and rolling resistance.
This study has shown that further improvement of wet skid and rolling resistance is possible by tailoring the silane structure.
Acknowledgements
The financial support from Gelderland-Overijssel within the GO program (EFRO 2007-2013) is greatly acknowledged. The authors thank Apollo Tyres Global R&D B.V., Enschede, the Netherlands, for their support. Elastomer Research and Testing (ERT), Deventer, the Netherlands, are acknowledged for their stimulating discussions.
References
1. European Union Patent No. EP0501227B1, (1992) 2. Thesis, L.A.E.M. Reuvekamp, Reactive mixing of
silica and rubber for tires and engine mounts, Enschede 2003
3. M. Heinz, Journal of Rubber Research 13 (2010) 91 TESPT 7 TESH 5.3 TESPT 9.5 TESH 7.3 TESPT 12 TESH 9.3 TESPT 14.4 TESH 11.3 95 96 97 98 99 100 101 102 Rating (%) Wet skid resistance at 8 °C 100 94 0 20 40 60 80 100 120 Rating (%) Tanδ at 60°C, 10 Hz/6% strain TESPT 7 TESDeT 9.5 TESPT 9.5 TESDeT 13 TESPT 12 TESDeT 16.8 TESPT 14.4 TESDeT 20.5 95 96 97 98 99 100 101 102 Rating (%) Wet skid resistance at 8 °C 100 115 0 20 40 60 80 100 120 Rating (%) Tanδ at 60°C, 10 Hz/6% strain TESPT 7 TESDeT 9.5 TESPT 7 TESH 5. 3
