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Study On Microscopic Mechanism Of Flex Fatigue Failure Of SSBR And Optimization Of Fatigue Resistance Of Tread Base

Posted on:2012-03-17Degree:DoctorType:Dissertation
Country:ChinaCandidate:X H SunFull Text:PDF
GTID:1111330371462466Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
Firstly, influence of factors such as micro-structure of SSBR, compounding ingredients, filler-filler and filler-rubber rubber network, chemical network, processing additive TT100, antioxidant 4020 on flex fatigue life of 6 types of SSBR, SSBR-T2003, T2530, T2000R, T1534, C2564A and VSL5025-1, with different micro-sructures were investigated. Influence of filler-filler, filler -rubber network and chemical network on flex fatigue life of SSBR vulcanizates was compared with the application of Rubber Processing Analyzer (RPA2000). Visco-elasticity, along with a new proposed parameter, strength/viscosity ratio (T2M*G"), was related with the flex fatigue life of SSBR vulcanizates. A network model of carbon black filled rubber was established based on the SEM morphology analysis of fatigue fracture interface combined with the analysis of mechanical properties and correlated with the failure mechanism of SSBR vulcanizates'flex fatigue.The results showed that:the flex fatigue life increased with the increasing of glass transition temperature and decreased with the increasing of loss modulus. Oil-extended SSBR with high 1,2-content had high flex fatigue life. The type of antioxidants and CB loads contributes more to the flex fatigue life than other factors. The flex fatigue life increased to the maximum value, then decreased with filler-filler and filler-rubber network density, while decreased with the increasing of chemical cross-linking density. Although the optimum CB loads for flex fatigue life of SSBR with different microstructure was different, the viscoelastic parameter of these samples fell in a very close range. The failure mechanism of SSBR was related to T2M*G". Rubber failed in mechanical strength failure mechanism when the value of T2/M*G" was lower, but failed in force-chemical failure mechanism when the value of T2/M*G" was higher. The protective effect of antioxidant 4020 was prominent when rubber failed in force-chemical mechanism. The physical meaning of T2/M*G" was the ratio of reinforcement of CB to hysteresis. The flex fatigue life increased with the increasing of T2/M*G" when only one factor was changed. Observation of SEM showed that there were potential defects in the compounds, and its influence on flex fatigue failure was less evident than that of T2/M*G" of CB filled rubber.Specimen of tread-based rubber from damaged tire with different fatigue history was analyzed with Fourier Transform Infrared Spectropy (FTIR), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Nuclear Magnetic Resonance Crosslink-density spectrometer (NMR-CDS). The essence and rule of fatigue failure was summarized and the failure mechanism concluded above was used to optimize the flex fatigue resistance for industrial practical application. The results showed that:high temperature degradation and mechanical fatigue were the main reasons for the fatigue failure of tread base. The uniform dispersion of CB particles played an important role on the fatigue failure performance of tires. The application of CB-DZ 13, special for low hysteresis of rubber, not only reduced the heat build-up, but also increased the resistance of flex cracking life significantly, but was negative to the resistance of crack growing properties. Application of oil-extended SSBR with high 1,2- content, combined with an adjustment on reinforcing system, improved the flex fatigue life of SSBR vulcanizates significantly. The SEM of fatigue failed interface presented a ravine-like morphology of exfoliated layers after long-term flex deformation and orientation.
Keywords/Search Tags:SSBR, Flex fatigue fracture, Microscopic mechanism, Tread rubber base, Cross-linked network
PDF Full Text Request
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