Study On Fatigue Micromechanism Of Nr/Ssbr Blends

Fatigue microscopic mechanism of NR/SSBR blends was studied. Five types of SSBR such as SSBR-T2530, T2003, RC2564S, RC2557S,72612S with different microscopic structure were mixed with NR. Influence of microscopic structure of SSBR, active agents, contents of filler, filler-filler and filler-rubber network on flex fatigue life of vulcanlizates was researched with the application of Rubber Processing Analyzer, Dynamic Mechanical Analyzer and Scanning Electron Microscopy. The relationship between dynamic mechanical properties of vulcanizates and flex fatigue properties was studied. The Model that can stand for flex fatigue of carbon black filled vulcanizates was established.The research showed that flex fatigue performance of vulcanizates increased with the increasing of glass transition temperature and decreased with the increasing of story modulus and loss modulus. Oil-extended SSBR with high1,2-content mixed NR had high flex fatigue life. Active agents had an obvious influence on flex fatigue life of vulcanizates. The chemical grade active agent with a large particle size had a good dispersion in rubber. It was not reunion easily that vulcanizates could get a high flex fatigue life.The content of carbon black and silica had a great effect on flex fatigue life of vulcanizates. Flex fatigue life rendered the trend that first increases and then decreases with the increasing of content of CB and silica. Payne effect caused by interaction of filler-filler was also a factor that affected flex fatigue life of vulcanizates. In blends, there was critical volume fraction. Only when the storage modulus, loss modulus, Payne effect and carbon black reinforcd effect to achieve a balance at the same time, flex fatigue life of vulcanizates was exhibited. Flex fatigue life of vulcanizates could be increased obviously after joining modifier GMA.Flex fatigue life of vulcanizates had a relationship with strength/viscosity ratio. Rubber failed in mechanical strength failure mechanism when the value of strength/viscosity ratio was lower, but failed in force-chemical failure mechanism when strength/viscosity ratio was higher. Flex fatigue life of vulcanizates increased with the increasing strength/viscosity ratio. SEM showed that flex fatigue could be divided into three stages—forming of micro destruction of nuclear, micro-crack growth and eventually leading to fracture. Heterogeneous model of flex fatigue was set up. The relationship between filler content and viscoelastic and flex fatigue was used to explained flex fatigue performance.