| Reinforcement is a fundamental issue in rubber science and engineering.The reinforcement of rubbers is most commonly achieved by compounding diverse nanoparticles(NPs)into the rubber matrices,such as carbon black,and silica.The incorporation of filler can greatly improve the comprehensive mechanical properties of rubber.Alternatively,a number of non-filling reinforcement methods such as the introduction of sacrificial bonding have been developed.However,all these methods inevitably sacrifice the unique elasticity of rubber,resulting in the deterioration of the dynamic performance of rubber.Accordingly,toward the great demand for high-strength,low-hysteresis rubber materials,in the present thesis,the author focused on the inherent contradiction between reinforcement and hysteresis in rubber,and carried out relevant research by improving the interfacial adhesion between filler and rubber and creating heterogeneous crosslinking.The main contents are as follows:(1)Based on the TAD-ene click chemistry,the urazole groups were successfully introduced onto NR chains.During the preparation of rubber composites,the pendent active urazole group can be converted to the stable urazole radicals by capturing the macroradicals or subjecting thermal oxidation,and then further captured by CB,attaching the rubber chain to the CB surfaces finally,which accordingly enhanced the rubber-CB interfacial interaction and carried out a quite uniform dispersion of CB with the suppressed filler network in NR matrix.As a consequence,the improved modulus and wet-traction of composites together with the strikingly reduced rolling-resistance,are simultaneously achieved at a suitable TAD grafting ratio.(2)A brand-new adamantyl-based imine DADI was synthesized as the interfacial mediator of NR/CB composites.By virtue of the radical scavenging capability of imine moieties,the obtained DADI was able to capture the macroradicals generated by the scission of rubber chains during compounding,and then stabilize them inside the adamantane functionalities.These DADI-capped macroradicals can subsequently transfer onto the CB surface,leading to the formation of covalent linkages between CB particles and rubber matrix,which greatly enhanced the interfacial adhesion and the dispersion of CB particles in the composites.Accordingly,with the incorporation of DADI,the resulting composites achieved remarkable reductions in heat generation and energy loss upon dynamic loading.Besides,the obtained DADI can also substantially improve the aging resistance of rubber matrix,through wiping out the reactive radicals generated during thermo-oxidative process.(3)A novel strategy of rubber-reinforced rubber(3R)with the combination of significant reinforcement and high elasticity is proposed by introducing the rubber particles crosslinked by polysulfides into a rubber matrix.With experimental/simulating integrated method,a brand-new reinforcing mechanism for rubber is disclosed,called soft matrix-induced large extensionability of hard rubber(“SMILE-HR”).The soft matrix endows the highlycrosslinked rubber particles(HPs)with the capacity of large extensionablity,so the molecular chains in HPs can be highly oriented and thus obtain high strength during stretching,which are primarily responsible for the dramatic reinforcement of 3R.This skillful combination of these two elastic constituents conquers the stubborn contradiction between reinforcement and hysteresis in rubber.(4)Two conventional diene-rubbers,ethylene propylene diene terpolymer(EPDM)and styrene-butadiene rubber(SBR),were adopted as thermodynamic incompatible pair and then directly admixed.Due to the significant difference in the cross-linking reactivity between the pair,the resulting system assembled into a microphase-separated structure with strong interfacial adhesion upon in situ co-cross-linking.Upon deformation,the overall chain orientation of the networks is promoted by the efficient interfacial stress transfer and a striking reinforcement of the networks is achieved accordingly.More importantly,by virtue of the slightly cross-linking attribute of EPDM component,the resulting system featured with desirable recyclability and high elasticity in comparison with conventional TPVs.Besides,in the sulfur crosslinking system,through the selective dispersion of cross-linking agent,we also constructed a heterogeneously crosslinked network in EPDM/SSBR,which significantly improved the mechanical properties of the elastomer network. |
