| High trans-1,4-poly(isoprene-co-butadiene)(TBIR),as a new type of synthetic rubber,can significantly improve the fatigue resistance,abrasion resistance,reduce rolling resistance and heat build-up of rubber materials,so it has the potential in the development of high-performance tires.However,TBIR,as unsaturated rubber,is prone to aging,resulting in failure of rubber products.In view of the high trans-1,4structure of TBIR and the special structure containing different lengths of butadienebutadiene sequences and isoprene-isoprene sequences,in order to explore the aging behavior of TBIR under different conditions and different cross-linking network structures,and to solve the key problems such as unclear anti-aging methods of TBIR,the following studies were conducted in this workThe aging behavior of TBIR under thermal oxygen,thermal shearing,processing and heat was studied.The changes of structure and properties of TBIR during aging were studied by using FTIR,GPC,MV,TGA and physical properties.The results showed that the oxidation reaction of TBIR resulted in the formation of oxidation products containing ketones and aldehyde,and the molecular weight and Mooney viscosity of TBIR decreased during thermo-oxidative aging.During thermal shearing aging,the elastic modulus and complex viscosity of TBIR decrease,and the molecular chain breaks.The thermal degradation reaction of TBIR is divided into two steps:isoprene degradation and butadiene crosslinking.After thermo-oxidative aging,the physical and mechanical properties of TBIR vulcanizates decreased.Compared with NR,the aging coefficient and property retention rate of TBIR vulcanizates after aging were higher,and the aging resistance of TBIR vulcanizates was better.The influence of different crosslinking network structures on the aging resistance of TBIR were studied.The crosslinking network structures of TBIR vulcanized adhesive were changed by cured different sulfur vulcanization systems.The results showed that compared with TBIR curing by conventional vulcanization system,the rubber cured by semi-effective vulcanization system has higher cross-linking density,modulus,hardness,better resilience and abrasion resistance,lower heat build-up and rolling resistance,but lower tensile strength,elongation at break and fatigue resistance.TBIR cured by SEV system has better resistance to thermo-oxidative aging and fatigue resistance.Compared with NR/BR,TBIR vulcanizate has better aging resistance,fatigue resistance and packing network structure stability.The influence of different antioxidants on the structure and properties of TBIR during thermo-oxidative aging were studied.DSC,FTIR and GPC were used to study the structural changes during aging.The results showed that the antioxidants could effectively improve the anti-oxygen ability of TBIR,effectively reduce the formation rate of oxidation products,and delay the breaking process of TBIR molecular chain,among which the antioxidant 4010 NA increased the oxidation induction time by 23 times,reduced the-C=O group by 60%,showing the best anti-aging effect.The influence of antioxidants on the tensile strength and elongation at break of TBIR was not obvious,but after aging 168 h,4010 NA significantly improved the fatigue resistance of TBIR vulcanizates by 41-46 times.Compared with NR/BR vulcanizates,TBIR vulcanizates have better abrasion resistance and dynamic fatigue properties. |
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