Design And Preparation Of High Damping Rubber Materials Under Large Shear Strain

Earthquake is a kind of devastating natural disaster.By installing seismic isolation bearings between the upper buildings and the foundations could significantly improve the seismic capacity of the buildings and avoid the damage caused by earthquake.Laminated rubber isolation bearings are the most widely used seismic isolation bearings,and include two main types of bearings,natural rubber bearings(NRB)and lead-core rubber bearings(LRB).However,the energy dissipation capacity of NRB is not satisfactory because of the poor damping performance of natural rubber.And the LRB suffers from the poor self-recovery capacity,poor shear fatigue resistance and environmental pollution problems.The development of high damping rubber bearings(HDR)could avoid the use of lead-core and solve the above problems.Rubber materials used in HDR are required to have high damping performance under large shear strain,which is difficult to meet by traditional rubber materials.Thus,to solve the above problems,we prepared novel high damping rubber materials by blending modification method and nano-damping technology.The damping modification mechanism of different modification methods was studied,and the influence of different fillers on the damping properties of rubber composites was explored.And we successfully prepared a series of rubber composites with high damping properties in a large shear strain range.The main research contents of this subject are listed as below:(1)For the first time,a novel sliding graft copolymer(SGC)was used for the damping modification of acrylate rubber(ACM)in this work.Firstly,we investigated the modification effect of SGC on the damping properties of rubber materials under large shear strain using rubber processing analyzer(RPA)by changing the blend ratio of SGC and ACM.And the results revealed that under high SGC content,the damping properties of rubber composites under shear strain increased significantly with increasing SGC content.The tan? value of the ACM/SGC(100/40)composite is about 1.94 times as high as that of the pure ACM rubber.Subsequently,we changed the preparation process by pre-crosslinking SGC materials,and explored the influence of the pre-crosslinking process on the properties of rubber composites.The results revealed that after pre-crosslinking SGC,the damping properties and mechanical properties of rubber composite were significantly improved.The tan? value of ACM/pre-SGC composite is about 12%times higher than that of ACM/SGC composite.In addition,rubber composites with different pre-crosslinked SGC content were prepared.The interfacial hydrogen bond interaction and a wide interaction interface were confirmed by Fourier transform infrared spectroscopy(FTIR)and atomic force microscopy(AFM)characterizations,respectively,which were the exact reasons of the improved damping properties of rubber composites.The prepared ACM/SGC rubber composite in this work has an excellent damping properties in a large shear strain range.The tan? value of the ACM/SGC(100/40)composite is about 1.84 times as high as that of the pure ACM rubber.(2)A new method for preparing multi-layer graphene nanoplatelets with low cost,environmental protection and simple operation process was developed.In this work,tea-polyphenols modified graphene nanoplatelets(TEG)was prepared by the exfoliation of expanded graphite(EG)under sonication in aqueous solution with the assistance of tea-polyphenols.It was confirmed by AFM,X-ray photoelectron spectroscopy(XPS)and Raman spectroscopy that the prepared TEG nanoplatelets were a kind of multi-layer(6-7 layers)graphene material with low structural defects.Subsequently,a novel TEG/carbon black(TEG/CB)hybrid filler was prepared by incorporating the prepared TEG nanoplatelets with CB.Then,styrene butadiene rubber(SBR)composites reinforced with TEG,CB and TEG/CB fillers were prepared by a latex compounding approach.The effects of different fillers on the mechanical properties and damping properties of rubber composites were investigated by tensile tester and RPA.The results revealed that a significant synergistic effect was observed in the hybrid filler reinforced rubber composites.SBR/TEG/CB composite exhibited significantly higher mechanical properties than other materials.The tensile strength of SBR/TEG/CB composite is about 20.6MPa,which is 587%times higher than that of SBR rubber.The rubber composites filled with carbon black filler exhibited significantly improved damping properties under large shear strain.The tan? value of the SBR/CB(100/20)composite is about 1.9 times as high as that of the pure SBR rubber.(3)The effect of conductive carbon black(GCB)on the damping properties of rubber composites under shear strain were investigated.Firstly,the micro-morphology and other characteristics of conductive carbon black were analyzed by means of high-resolution transmission electron microscopy,XPS,Raman spectroscopy and BET specific surface area tester.And several important factors determining the high conductivity of GCB were obtained by comparing GCB with common carbon black and graphene oxide,which are high specific surface area,high structural degree and surface cleanness.Then,SBR composites reinforced with GCB,TEG and GCB/TEG hybrid filler were prepared.The dispersion of different fillers in the rubber matrix were investigated by transmission electron microscopy(TEM).And the effects of different fillers on the vulcanization properties,mechanical properties,electrical conductivity,thermal conductivity and damping properties of rubber composites were investigated.The results revealed that,due to the formation of a better filler network,the damping properties of rubber composites under shear strain were significantly improved after filled with GCB.The tan? value of SBR/GCB(100/20)composite is about 0.527,which is about 6 times as high as that of SBR rubber.Besides,rubber composites filled with GCB exhibit high mechanical strength,whose tensile strength is about 18.6MPa,which is about 5.5 times as high as that of SBR rubber.Moreover,SBR/GCB composite possesses good electrical conductivity,thermal conductivity,and excellent comprehensive properties.(4)The modification effect of tea polyphenols on the dispersion of carbon black in rubber matrix and the damping properties of rubber composites were investigated.The modification effect of tea polyphenols on the dispersion of carbon black in rubber matrix was studied by TEM and RPA.And the results revealed that,tea polyphenols could be adsorbed on the surface of carbon black by ?-? interaction,which could prevent particle from aggregation and improve the dispersion of carbon black in rubber matrix.However,adding too much of tea polyphenols into rubber matrix could affect the vulcanization characteristics of rubber material and reduce the crosslinking density.Besides,after adding TPs,the damping properties of rubber composites under shear strain is significantly improved.The tan? value of SBR/TCB composite is about 0.186,which is 1.63 times as high as that of SBR/CB composite and 2.07 times as high as that of SBR rubber.Subsequently,the effects of blending ratio of tea polyphenols and carbon black on dispersion of carbon black and vulcanization properties,mechanical properties,damping properties of rubber composites were investigated.The results revealed that rubber composites with excellent comprehensive properties could be obtained by optimizing the blending ratio.The obtained rubber composites not only maintain high mechanical properties,but also possess high damping properties under high shear strain.