Study On Fatigue Properties Of BR/TPI Blends

When Trans-1,4-polyisoprene (TPI) blended with general rubber in proper proportion, the dynamic performance of blend vulcanizates can be significantly improved, this may be related to the crystallization of TPI and the regularity of its chain segments. In this research, butadiene rubber (BR) was chosen to blend with TPI, the dynamic mechanical properties of BR/TPI blends were examined, crosslink density, mechanical properties, dynamic and TPI crystallization performance changes BR/TPI blend vulcanizates during fatigue process of were studied.The results showed that, as increasing TPI content, the TPI residual crystallization, tensile strength, Modulus at100%and tear strength gradually increased; the tanδ peak、resilence and heat aging properties declined gradually, and Tg moved towards lower temperature. Moreover, when the dosage of TPI was below30phr, flexible fatigue performance of BR/TPI blends was excellent, and along with increasing TPI content, roughness of their surface fractures increased; The tensile strength, crosslink density and deformation energy density reached the maximum when the cycles of tensile fatigue came to600000, and the diffraction peak of TPI crystallization in the blend vulcanizates changed constantly during fatigue process.Effects of dynamic fatigue on performances of BR/TPI (90/10) blends with different content of sulfur were studied. Results showed that, as increasing sulfur content, the crosslink density of the blend vulcanizates increased, but the tensile and tear strength decreased. In the tensile fatigue process, the strain energy density and crosslink density of BR/TPI blends with1.5phr sulfur increased gradually, when sulfur content went up, those of BR/TPI blends increased slowly in the early stage of fatigue process, and then dropped significantly.Influence of dynamic fatigue on carbon black filled BR/TPI (90/10) blends was investigated. Results showed that, with carbon black particle size increasing, filler-filler network effects of BR/TPI blends weakened, tanδ peak increased, tanδ and E’ at high elastic state reduced, and rolling resistance declined; Hardness, modulus and wear resistance decreased, elastic, breaking elongation and tear strength increased; In tensile fatigue process, crosslink density and strain energy density of BR/TPI blend vulcanizates filled with different types of CB declined slowly; tanδ peak of BR/TPI blends filled with CB N220in glass transition region were steadily decreasing, while tanδ peak of BR/TPI blends filled with CB N330and N550decreased in the early stage of fatigue process, and then increased. Along with the increase of CB N330content, crosslink density and strain energy density of BR/TPI blends rose up, carbon black network effect enhanced, E’、hardness, tensile and tear strength increased, elasticity and tanδ peak decreased; With the increase of tensile fatigue cycles, crosslink density, strain energy density and tensile performance of BR/TPI blend vulcanizates were falling steadily, tan8peak of BR/TPI blends filled with70phr CB N330were decreasing, while tan8peak of BR/TPI blends filled with30and50CB N330decreased in the early stage of fatigue process, and then increased at I million fatigue cycles.Effects of dynamic fatigue on performances of BR/TPI (90/10) blends with different type of fillers were studied. Results showed that, the filler-filler network level of BR/TPI blends were as follows:CB N330filling rubber>Silica filling rubber>CSDPF filling rubber, strength, wear resistance and flexible fatigue resistance performance of CSDPF filling rubber were be superior to CB N330filling rubber and Silica filling rubber; tanδ peak of BR/TPI blends were as follows:Silica filling rubber>CSDPF filling rubber>CB N330filling rubber, the sequence of tanδ of BR/TPI blends at high-elastic state was totally opposed; In tensile fatigue process, tensile strength and crosslink density of CSDPF, CB N330and Silica filling rubber declined slowly; tanδ peak of CSDPF and Silica filling rubber were steadily increasing, while tanδ peak of CB N330filling rubber decreased in the early stage of fatigue process, and then increased slightly at the late stage of fatigue process.