Natural Rubber/Nitrile Rubber/Epoxidized Natural Rubber Composite And Application On Seismic Bearing

Seismic bearing is an important facility to protect bridges and buildings from destruction of earthquakes. The rubber materials used for seismic bearing are required to have excellent overall performance, such as high damping, good flexibility, high elasticity and high strength. However, a single rubber cannot meet all these requirements.Our research has made use of high strength, high elasticity and low permanent set from natural rubber?NR?. We has added nitrile rubber?NBR? or hindered phenol/nitrile rubber?NBR/AO-80? into NR matrix, and added epoxidized natural rubber?ENR? as compatibilizer to prepare NR/NBR/ENR and NR/NBR/AO-80/ENR composites successfully. Influence of ENR types and contents on microstructure, damping property, mechanical property and crystallization behavior were studied using SEM, AFM, DSC, DMA, RPA, WAXD. The main work was as follows.1. NR/NBR/ENR composites were prepared. DMTA curves show two glass transition temperatures, corresponding to NR phase?Tgl?and NBR phase ?Tg2?. For NR/NBR, tan? value of Tg2 peak is 0.33 and temperature range of tan?>0.1 is -68??15.50?. They change little with ENR content, but change a lot with the epoxidation degree of ENR. Compared with NR/NBR system, mechanical properties of NR/NBR/ENR are better, and this is attributed to the compatibilizing effect of ENR. NR/NBR/ENR25 ?70/30/5? composite shows the best tensile strength ?23.7MPa? and elongation at break ?782%?.2. NR/NBR/AO-80/ENR composites were prepared. DMTA curves show two glass transition temperatures, corresponding to NR phase ?Tg1? and NBR/AO-80 phase ?Tg2?. The temperature range of tan?>0.3 on peak 2 is about 20 ?. Solubility parameter of ENR25 is 18.72?J/cm³?^1/2, which is between that of NR (16.6?J/cm³?^1/2) and NBR (21.0 ?J/cm³?^1/2), so ENR has compatibilizing effect on NR/NBR system. ENR dispersed at the interface of NR and NBR/AO-80, and improved the resilience of damping phase, leaing to excellent comprehensive properties of NR/NBR/AO-80/ENR. Mechanical properties of NR/NBR/AO-80/ENR?70/30/12/10? exhibit the best dispersion and mechanical properties, and its tensile strength exceed 23.6MPa. At large deformation ?a>2.5?, crystallization and orientation occurred in NR phase and NBR phase, respectively.3. Carbon black-contained NR/NBR/AO-80/ENR composite was prepared and used to manufacture high damping rubber bearing?HDR?. Vertical stiffness and horizonal stiffness are 854 kN/mm and 2.0 kN/mm, respectively. Equivalent damping ratio is 17.2%. They all meet the standard and are better than bearing made of carbon-filled NR ?horizonal stiffness: 1.4kN/mm; equivalent damping ratio:13%?.