Study On The Design Of Preparation, Structure And Properties Of Energy-Saving Rubber And Organic Silica-Polyisoperene Copolymer Particles

Recently, with the demand of energy conservation and emission reduction in our country and the development of automotive industry in security, comfort, and energy-saving, there are increased requirements of tire with good abrasion resistance, high wet-skid resistance, and low rolling resistance. However, the three performances are hard to be improved simultaneously. Therefore, the design of molecular structure of energy-saving rubber is one of research focuses. Besides, SiO2 is widely used in the tire tread compound for high reinforcing and low heat build-up. However, silica is easy to aggregate and weak interaction with rubber matrix. Therefore, how to get better filler dispersion and improve the filler-rubber interaction through molecular structure design, and nano-filler reinforcement is the main research direction of this thesis. In the first part, we studied the preparation, characterization, structure, and property of end-functionalized SSBR. The functional groups that can either react with the nano-filler or inactivate the free chain ends were introduced in the last stage of anionic polymerization. On one hand, star-shaped SSBR with the alcoxyl groups on the one end of macromolecular (AS-SSBR) were prepared by anionic polymerization using a multifunctional organic lithium initiator. The molecular structure parameters of AS-SSBR were determined and the end-functionalized efficiency was calculated. The results of TEM and X-ray energy spectrometry showed that SiO2 and CB filled AS-SSBR composites exhibited outstanding doping nanometer dispersion, excellent mechanical properties, high wet-skid resistance, and low rolling resistance. The comprehensive properties of AS-SSBR composites filled with SiO2-CB were better than those of star-shaped SSBR. AS-SSBR was a remarkable energy-saving rubber. On the other hand, linear SSBR with the large-volume functional groups on the one end of macromolecular were prepared by anionic polymerization using 1,1-diphenylhexyllithium (DPHL) as initiator prepared by addition reaction between n-butyllithium and 1,1-diphenylethlene. SnCl4 as coupling agent was added in the last stage of polymerization, and then coupled SSBR with the large-volume functional groups on the one end of macromolecular (DS-SSBR) was prepared. The interaction of CB with DS-SSBR and the dispersion of filler had been improved because of the large-volume functional groups. The results showed that DS-SSBR composites presented long relaxation time and low internal friction owing to the large-volume functional groups, which can restrain the movement of the molecular chain ends of DS-SSBR, and adsorb CB. The DS-SSBR composites can achieve excellent balance between wet-skid resistance and rolling resistance, therefore the DS-SSBR was energy-saving rubber for the tread.In the second part, we studied influence of the addition level of coupling agent on mechanical properties, dynamic properties and microstructure of silica-CB filled star-shaped SSBR (S-SSBR). By comparing properties of star-shaped SSBR filled with silica-carbon black with those of AS-SSBR filled with silica-carbon black, the influence of reaction site position between silica and SSBR on structure and properties of silica-CB/SSBR composite were investigated. The results showed that, as the addition level of coupling agent (mole of siloxane group) increased, the modulus and tensile strength of star-shaped SSBR composites and AS-SSBR composites increased; the elongation at break and dynamic compression heat built-up decreased. When the mole of siloxane group in composites was the same, the increasing amplitude of modulus at 300% and the tanδvalue at 0℃, and the decreasing amplitude of dynamic compression heat built-up and tanδvalue at 60℃of AS-SSBR composites were higher, the dispersion of fillers was better. The AS-SSBR composites (silica attached to the end of macromolecular) possess better filler-dispersion, higher wet-skid resistance and lower rolling resistance than S-SSBR composites (silica attached to any position of macromolecular).In the third part, we studied the preparation and characterization of organic silica-polyisoprene copolymer particles and the properties of NR filled with organic silica-polyisoprene copolymer particles. Silica was organically modified by KH570 to attach the C=C to the surface of silica, then oxidation-reduction initiator was designed to initiate the free-radical emulsion polymerization which occurred in the interface. So that organic silica-polyisoprene copolymer particles was prepared successfully. The product was characterized by FT-IR, TEM, and TGA. The mechanical properties, dynamic properties and microstructure of organic silica-polyisoprene copolymer particles filled NR were investigated. The results showed that organic silica-polyisoprene copolymer particles filled NR composites presented excellent mechanical properties, and outstanding dispersion.