Study On Fatigue Properties Of SBR/TPI Blending Vulcanizates

Trans-1,4-polyisoprene(TPI) can significantly improve the dynamicperformance of blend vulcanizates when blended with general rubbers,especially the fatigue properties. This may be related to its uniquecrystalline. In this paper, amorphous styrene-butadiene rubber (SBR) waschosen to blend with TPI. Studies were focused on the effect of TPIcontent and filler on the fatigue properties of SBR/TPI blendingvulcanizates, and the changes of TPI crystallinity in the fatigue processcharacterized by differential scanning calorimeter(DSC) and X-raydiffraction(XRD).The results showed that, with increasing the TPI content, the TPIresidual crystallization, tensile strength, Modulus at100%and tearstrength improved gradually, the tanδ peak, resilence, DIN abrasion resistance and heat aging properties declined gradually, and Tg movedtowards lower temperature.The tensile fatigue properties improved evidently, when TPI contentwas20and30phr. As increased the TPI content, the fatigue fracuturebecame rougher. The changes of structure and performance of SBR andTPI20vulcanizates with different fatiuge cycles were studied. The resultsshowed that, as the fatigue cycles increased, the structure andperformances of SBR vulcanizates changed obviously, the crosslinkdensity increased first and then decreased, tanδ peak and E′decreasedsignificantly, while the crosslink density of TPI20vulcanizates increasedslightly, tanδ peak and E′trends were not pronounced. there are α and βtwo kinds of crystals in the SBR/TPI blend vulcanizates Thecrystallization diffraction peaks intensity increased gradually with longerfatigue, and there was a new crystallization diffraction peak where theinterplanar distance was7.6. The flexing fatigue property was best whenTPI content was20phr, while the fatigue fracture was roughest compared with others.Compared the Properties of carbon filled SBR/TPI vulcanizates withunfilled samples, the crystalline melting enthalphy and tanδ peakdecreased significantly, tensile strength, tear strength, DIN abrasionresistance increased, resilence denclined.SBR/TPI filled vulcanizates had the best tensile fatigue performance,when TPI content was20phr, the fatigue life prolonged greatly. Thefatigue fracture was rougher, and there was a round crack point, thefracture propagated radially from ponint. As the fatigue cycles increased,the properties of carbon filled SBR vulcanizates declined significantly,tensile strength and crosslink density drastically reduced, tanδ peak valueand E′slightly reduced; while the properties of TPI20filled vulcanizatesdecreased less than that of SBR filled vulcanziates, the tensile strengthdecreased first and then increased, the crosslink density reduced slightly,and the dynamic properties did not change significantly. The XRD resultsshowed that the crystalline diffraction peak intensity became lower after carbon filled. During the fatigue progress, the crystalline diffraction peakintensity increased slightly, and there also appeared a new crystallinediffraction peak corresponding to7.6interplanar distance. When TPIcontent is20phr, SBR/TPI filled vulcanizates had the best flexing fatigueperformance, the fatigue fracture of which is roughest.