Study On Damping Properties Of SIBR With Different Hydrogenation Degree

The Styrene-Isoprene-Butadiene random copolymer SIBR was synthesized by living anionic polymerization method using cyclohexane as solvent and n-butyllithium, N,N,N'N'-tetramethylethylenediamine(TMEDA) as initiator and microstructure modifier, respectively. A series of tailor-made molecular weight, microstructure and narrow molecular weight distribution SIBR were obtained by macromolecular design methods and living anionic polymerization techniques. The 1,2-microstructure in polybutadiene segment and 3,4-microstructure in polyisoprene segment was regulated by strong polar modifier TMEDA. FT-IR,1H-NMR and GPC were used to analyze molecular weight and their distribution, microstructure content of SIBR. The results indicted that molecular weight and microstructure content of synthesized SIBR consistent with the designed parameters, also fully adjusted to living anionic polymerization features.SIBR was hydrogenated by nickel naphthenate(Ni)/triisobutyl aluminum(Al) homogeneous catalyst system. The reaction temperature was 60℃, hydrogen pressure was 4MPa, catalyst amount was 2mgNi/g dry polymer, Al/Ni was 5, reaction time was 3 hour. And then much attention was paid on different modifier additives, i.e. TMEDA,2G and THF and their effects on the above catalyst system. The degree of hydrogenation was evaluated by chemical titration method. Experiment results showed that TMEDA had a significant effect on hydrogenation reaction,2G came second and THF the last. These differences can be explained from the point of coordination chemistry. Samples with hydrogenation degree range from 20% to 80% can be accurately obtained by using TMEDA as polar additive. TMEDA can also make the hydrogenation reaction benign and reduce the side reactions efficiently, these contributions can be explained indirectly from the temperature-heat effect during the hydrogenation reaction.After mixing and vulcanizing, different types of hydrogenated samples can be obtained. And then physical mechanical properties such as, tensile, aging and hardness(Shore A) experiments were undertaken. Special emphasises were put on the monomer proportion, different degrees of hydrogenation and their effects on the dynamic mechanical properties of the samples.Experiment results indicted that polymer properties were degraded by aging reaction, hydrogenation can improve aging properties of SIBR effectually. Under the same aging time, the higher the hydrogenation degree the smaller physical mechanical properties degrade of the sample. Monomer proportions have an obvious effect on the dynamic mechanical properties of the polymer, the higher content of isoprene in the monomer the bigger effect on physical mechanical and dynamic mechanical properties of the polymer.The hydrogenated SIBR can be used as damping materials, in this paper we analyzed monomer proportion and hydrogenation degree and their effects on damping properties of SIBR. The relationship between Tan Delta, Storage Modulus, Loss Modulus and degree of hydrogenation should be on the top agenda. The results showed that in the lower hydrogenation spectra, the more isoprene in the polymer the higher Loss modulus, the better physical mechanical and aging properties of the polymer.