Design And Preparation Of High Performance Ruber Composites Used In Seismic Bearing

As an effective measure to improve the seismic capacity of buildings and bridges,rubber isolation bearing has been widely studied and applied in many countries in the world.The ideal material used in rubber bearing should have high strength,high elasticity,high damping,high flexibility and so on.But a single rubber cannot meet all these properties at present.Natural rubber(NR)is the frequently-used material for rubber bearing,but it must be used with the lead metal or damping device to meet the requirements because of its poor damping property.Therefore,it is of great significance to prepare high performance rubber composites material for isolation bearings.In our research,the hindered phenol AO-60 was added to nitrile rubber(NBR)by a specific process to prepare high damping NBR/AO-60 hybrid materials,and then blended with NR,using epoxidized natural rubber(ENR)as compatibilizer,a series of NR/NBR/AO-60 and NR/NBR/AO-60/ENR rubber composites were preopared by adjusting the blending ratio of the composites.The blending ratio,influence of ENR epoxy degree and use level on combination properties were studied using TEM,AFM,DSC,DMA,RPA,WAXD and so on.The rubber composite material with good mechanical properties and excellent damping properties was obtained.The main work and results are as follows:1.The NR/NBR/AO-60 composites with different ratios were prepared.The micromorphology shows "sea-island structure",and the continuous phase is NR,the dispersed phase is NBR/AO-60.The dispersed phase is between several micrometers and several tens of micrometers.When the ratio of NR/NBR/AO-60 is 50/50/20,some double continuous-phase structure appears in the system,and the compatibility is improved;The composite exhibits two loss peaks,with the increase in NBR/AO-60 content,the peak value tanδmax of the NBR/AO-60 phase increased from 0.13 to 1.12,the damping temperature △T of tanδ≥0.3 is broadened from 11.8℃ to 26.5℃。The damping properties significantly increase in-20℃-40℃ temperature range and 0-150%strain range.Besides,the tensile strength reach to 15.5 MPa,and elongation at break reach to 855%when the ratio of NR/NBR/AO-60 is 50/50/20.2.The NR/NBR/AO-60/ENR composites were prepared by adding ENR with different epoxidation.The effect of ENR types and contents on the properties of the composites was investigated.With the increase of ENR epoxidation,the dispersed phase becomes smaller(about 2-6 μm)and the dispersion becomes uniform.NR/NBR/AO-60/ENR50 composite material has the best damping performance,NBR/AO-60 phase has the highest tanδ and the widest damping temperature range,which is better than that of the other two ENR composites.ENR50 has the greatest improvement in mechanical properties,compared with the NR/NBR/AO-60,the tensile strength increased by 43.4%,and the elongation at break increased to 684%.ENR content also has a greater impact on the composite material,NR/NBR/AO-60/ENR50(70/30/12/15)has the best performance,tanδ≥0.3 temperature range from 1℃to 20.6℃,and tanδ peak value is more than 0.6.Besides,the tensile strength increased by 68%compared with the NR/NBR/AO-60.3.The NR/NBR/AO-60/ENR50 composites with different ratios were prepared.The microphase phase changes from the "sea-island structure" to the"double continuous-phase structure".ENR50 is dispersed as a compatibilizer at the interface of the two phases.Three loss peaks appear on the DMA curve,and the loss peaks at room temperature shows bimodal overlays of NBR/AO-60 and ENR50.The tanδmax of these loss peaks increase from 0.15 to 0.76,at the same time,the damping temperature △T of tan8>0.3 is broadened from 6℃to 36.5 ℃.The blended composite material still has the property of strain-induced crystallization,which ensures high tensile strength and elongation at break.4.NR/C5 and NR/C9 petroleum resin composites were prepared.The petroleum resin acts as a plasticizer,and the tensile stress of the composite decreases.The damping performance of the composite material is greatly improved and the loss peak moves to the high temperature direction.The damping temperature(tan δ≥0.3)of NR/C5 range from 28.9℃ up to 39.9℃,and NR/C9 range from 28.9℃up to 41.8℃.The damping temperature range is significantly wider.