Preparation And Properties Of Organic Montmorillonite /EPDM Rubber Sealing Material

Though ethylene propylene diene monomer rubber (EPDM) sealing material owns excellent mechanical properties and ageing resistance, it will lose its effectiveness after affected by light, heat, oxygen and corrosive substance during service life. One of the useful methods to improve the durability of EPDM sealing material is modification that is of great significance to enhance the properties of EPDM sealing material and prolong its lifespan.The organic montmorillonite (OMMT) modified EPDM sealing material was prepared with different contents of OMMT. The structure was characterized by X-ray Diffraction (XRD). The effect of OMMT on mechanical properties, corrosion and ageing resistant performance, as well as lifespan of EPDM sealing material was investigated. The results are as follows:(1) XRD analysis shows that exfoliated nanocomposites are formed in 5 phr and 10 phr OMMT modified EPDM sealing material, while intercalated nanocomposites are formed between 15 phr OMMT and EPDM sealing material.(2) The barrier ability to gas and solution is improved with addition of OMMT. The air transmission coefficient of OMMT modified EPDM sealing material (10phr) reduces by 26.5% in comparison with unmodified EPDM sealing material. The ratio of water absorptivity under 0.3MPa reduces by 14.3% for OMMT modified EPDM sealing material after 24 hours.(3) The corrosion resistance to both H2S gas and H2S solution is enhanced by OMMT. The rank of the enhancement by different contents of OMMT is:10 phr> 5 phr> 15 phr. The break-strain energy of OMMT modified EPDM sealing material (lOphr) is improved by 39% after corroded in H2S gas for 20 days.(4) Compared with unmodified EPDM sealing material, the retentions of tensile strength, elongation at break and break-strain energy are bigger whereas the change of hardness is smaller for OMMT modified EPDM sealing material after thermal oxidative ageing and alternate immersion ageing. The OMMT modified EPDM sealing material shows better ageing resistance to thermal oxidative ageing and alternate immersion ageing. (5) The predictive lifespan of OMMT modified EPDM sealing material increases by 31.84% and 38.04% in comparison with normal EPDM sealing material at 23 and 15℃, respectively.(6) The mechanisms of OMMT's improvement on corrosion resistance and ageing resistance of EPDM sealing material can be ascribed to the formation of exfoliated or intercalated nanostructure between OMMT and EPDM sealing material, which endows better barrier ability against gas, solution and heat into the inner of EPDM sealing material.