Co-vulcanization of eucommia ulmoides gum-styrene butadiene rubber composite system and its dynamic and static mechanical properties

Eucommia ulmoides gum (EUG) was blended with styrene butadiene rubber (SBR) to prepare EUG-SBR composites. The co-vulcanization was characterized by stripping experiments and tensile experiments, and the effect of EUG content on the dynamic properties of the composites was studied via tensile experiment, SEM, DMA and XRD. The results display that the prepared sulfide formula (mass ratio of accelerant N, N-dicyclohexyl-2-benzothiazole sulfonamide (DZ) 1.0% (based on the mass of EUG- SBR), accelerant tetramethylthiuram disulfide (TMTD) 0.1%, sulfur 1.5%) could achieve better co-vulcanization of the two rubbers. The stripping strength of the two rubbers reaches 4.2 kN/m and the tensile strength (mass ratio of SBR∶EUG=70∶30) could reach 6.3 MPa. The EUG phase in the composites mainly exists in β-crystalline form, and with the EUG content increasing, the crystallinity and melt temperature of the composites are significantly improved. The introduction of EUG decreases the peak loss factor tanδ_max value and increases the storage modulus of the composites. At temperatures of 10 ℃, the storage modulus of EUG-SBR composites increases from 3.0×10⁶ Pa (with 5% mass of EUG) to 1.7×10⁷ Pa (with EUG of 35%). At the same time, the presence of crystal zone plays a role of physical crosslinking points to improve the tensile strength and fixed elongation stress of composites.