| In view of the problem of aging and discoloration of sidewall rubber,it is proposed to blend silicone rubber(VMQ)with excellent aging properties and butadiene rubber(BR)with excellent fatigue properties,and carry out systematic research of its co-vulcanization characteristics,microstructure,aging resistance,fatigue performance in order to prepare the sidewall rubber composite that will not cause discoloration and pollution,finally expand the application of VMQ in tires.The effects of VMQ/BR combination ratio,the dispersion state of silica in the two rubber phases,and the synergy of VMQ and antioxidants on the properties of the composites were mainly studied.The specific contents are as follows:1.Through the preparation of VMQ masterbatch,the difficulty of blending VMQ and BR can be solved.The system performance test of VMQ/BR composites with different combination ratios were studied,including thermal oxidative aging resistance,ozone aging resistance,crack propagation resistance,vulcanization performance,RPA test and wear resistance test,etc.Conclusion:On the one hand,it can be seen from the tests of the thermal oxidative aging resistance and the ozone aging resistance that the comprehensive aging resistance of the 20/80 composite is the best;the dynamic crack propagation resistance test under a constant tear energy(G=1000 J·m-2)shows that the 20/80 composite is also the best;it can be seen that the VMQ/BR blends can achieve the co-vulcanization effect through the vulcanization curve and vulcanization characteristic parameters.On the other hand,it can be seen from the RPA of the rubber composites and the microscopic morphology observed by transmission electron microscopy(TEM)that the incorporation of VMQ will lead to uneven distribution of silica within the rubber matrix.2.The microphase state and crystallization of VMQ/BR composites different blend ratio were studied including atomic force microscope(AFM),transmission electron microscope(TEM),differential scanning calorimeter(DSC),dynamic mechanical thermal analysis(DMTA)and Mooney-Rivlin curve analysis,etc.Conclusion:with the increase of VMQ content,the distribution size and shape of VMQ in the BR matrix are more uneven from AFM and TEM,indicating that the compatibility of the two rubber was worse.In addition,it was found that the silica particles in the VMQ masterbatch were distributed at the two-phase interface because of the closer surface energy of silica and BR;as the VMQ content increased,BR crystals increased at low temperatures and strain-induced crystals(SIC)also increased at room temperature,indicating that VMQ addition can promote the crystallization of BR;finally,the strain-induced crystallization of BR and the phase distribution of VMQ together lead to the improvement of the aging resistance of VMQ/BR composites.3.The VMQ/BR composites with different antioxidant contents were characterized by systematic aging performance,including thermal oxidative aging resistance,static ozone aging resistance and dynamic ozone aging resistance.The results showed that under the comprehensive comparison of thermal oxygen aging and ozone aging resistance,using 20 parts of VMQ can reduce the content of 0.5 parts of antioxidants while ensuring that the aging performance of the rubber compound is not affected. |
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