The Flexing Fatigue Property Of NR/LCBR Blends

This issue is about the flex fatigue properties of NR/LCBR blends. Influences of microstructure, carbon black filled rubber network, vulcanization network and other factors of vulcanizates were investigated respectively on flexure fatigue properties, with the application of rubber process analyzer (RPA2000), dynamic mechanical properties of spectrum analyzer (DMTS), scanning electron microscopy (SEM), gel permeation chromatography (GPC), nuclear magnetic resonance crosslinking density tester, stereo zoom microscope, conventional mechanical properties and other testing methods. According to the examination result of RPA, the effects of vulcanizates’ filler network and curing network on flex fatigue property were analysised. At the same time, correlation of vulcanizates’ flex fatigue property and viscoelastic property were investigated, combined with the correlation analysis of the mechanical properties and fatigue crack morphology analysis of SEM vulcanizate. Microcosm ic mechanism of NR/LCBR vulcanizates’ flex fatigue damage was discussed preliminarily.Research shows that:compared to other four kinds of NR blends (mixing with SSBR, ESBR, EPDM and BR) and pure NR, flex fatigue property of NR/LCBR vulcanizate was the best, as high as 560 kilocycles; with increase of crosslinking density, six level flex fatigue properties increased at first and then decreased; six level flex fatigue properties has a good negative correlation with 1/G"7o%S and glass transition temperature. When using N375, NR/LCBR vulcanizates’ flex fatigue properties came to the best, reaching about 1630 kilocycles; when CB/silica ratio was 35/15, carbon black dispersion the best, with minimum payne effect, flex fatigue properties came to the best, reaching about 820 kilocycles. The results showed that carbon black dispersion, crosslinking density and loss modulus significantly affected flex fatigue properties. NR/LCBR blends reinforced with N375/SiO2, at 35/15 ratio, could get a better dispersion of carbon black, higher crosslinking density, better dynamic loss modulus, and improve the flex fatigue property.