Processing And Properties Of Fluororubber Composites Affected By Novel Anti Aging Mechanism

With the in-depth development of oil and gas fields,China’s oil and gas extraction is facing the problems of low cumulative production,low recovery rate and more difficulty in development,conventional oil and gas resources are gradually depleted,and the national energy security is facing great challenges,so the development of unconventional oil and gas resources has become the focus of the next step of oil and gas extraction.To meet the complex working conditions of unconventional oil and gas exploitation,the development of high-performance oil extraction tools has become a core technology for unconventional oil and gas exploitation.The packer assembled with high-performance rubber barrel is one of the key components.In order to meet the sealing requirements for different environmental media with excellent sealing effects.Rubber composites for high-performance packer must have excellent mechanical properties,good toughness,elasticity,and aging resistance.As increasing technical indicators of temperature and service life for advanced equipments in oil and gas development,aviation,and machinery edc.,the construction and development of high-performance rubber technology systems for special environments is of great significance.In order to further improve the thermal oxidative aging performance of rubber,investigation of replacement of traditional anti aging technologies with new anti aging systems has been becoming a focus and hotspot.In this thesis,the study focused on novel composed technologies for carbon materials with sp² hybrid structure and new additives with free radical induced chemical reactions in the fluororubber matrix,the effects of these additives on the mechanical properties and aging resistance of fluororubber were investigated to achieve further improvement of the aging resistance of fluororubber and extension of its service life in unconventional high-temperature environments.This thesis mainly consists of three parts as follows.In the first part,fluoroelastomer（FKM）/multi-walled carbon nanotubes（MWCNTs）composites were prepared to extend the service life of packer sealing materials,and the effects of MWCNTs on the vulcanization parameters,mechanical properties,aging resistance and dielectric resistance of FKM were investigated separately.The results showed that the maximum torque（M_H）and positive curing time(T₉₀)increased gradually with the increase of MWCNT content.The tensile strength and hardness of FKM composites showed an increasing trend and the elongation at break showed a decreasing trend.The FKM composites showed good aging resistance when aged in dilute oxygen environment at 177℃,204°C and 232℃for 192 hours.After immersion in an acidic mixture of 20%H₂SO₄,28%NH₃-H₂O and p H 1 for 192 h,the mechanical properties decreased slightly during the experimental period.The high temperature aging resistance and corrosion resistance of the FKM composites in the medium did not show a positive correlation with the MWCNTs content.Appropriate addition of MWCNTs showed better enhancement.In the second part,three reagents,solid MDI,liquid MDI and IPDI,were used to chemically graft graphene oxide for better exfoliation between the lamellae of graphene,and the effect on the performance of fluoroelastomer was investigated by compounding it with fluoroelastomer.The results showed that the three different isocyanate reagents could successfully graft with the oxygen-containing functional groups on the surface of graphene,and the best effect of layer spacing expansion of graphene oxide modified with liquid MDI was achieved.After the aging test at 180℃,it was shown that graphene showed enhanced anti-aging ability for both rubbers,and the aging resistance of the IPDI-modified graphene oxide compounded fluoroelastomer composite was worse than that of the blank sample,and the rubber lost its performance after 4 days of aging.The anti-aging behavior of the fluoroelastomer compounded with solid MDI and liquid MDI modified graphene oxide was better,in terms of tensile strength,the blank sample exhibited a tensile strength retention of 85.8%after aging for 144 h,while the tensile strength of the solid MDI modified graphene oxide compounded fluoroelastomer was92.7%,while the tensile strength of the liquefied MDI modified graphene oxide compounded fluoroelastomer showed a slight increase The tensile strength of the liquefied MDI-modified graphene oxide compounded fluoroelastomer showed a slight increase of 3.8%compared with that before aging,and the elongation at tearing changed similarly to the tensile strength before and after aging,with an increase of 1.0%.The modified graphene with sp² structure exhibited excellent anti-aging effect by the electron leaving domain physical inhibition aging mechanism.In the third part,a new additive of HNTs loaded with zinc methacrylate（ZDMA）was prepared,and the effects of the new additive of HNTs loaded with zinc methacrylate on the vulcanization characteristics,mechanical properties and aging resistance of fluoroelastomers were investigated.The results showed that:the one-dimensional lumen of elosite was loaded with ZDMA particles,and some ZDMA particles were adsorbed outside the lumen,and the new additive showed certain enhancement effect on fluoroelastomer,and the tensile strength retention of fluoroelastomer composite was above 95.8%after high temperature aging at 180℃,while the tensile strength retention of fluoroelastomer composite of HNTs without ZDMA loading was 84.2%,and the tensile strength retention of blank The tensile strength retention of the sample was 81.3%,and the chemical inhibition aging mechanism of the new additive of HNTs loaded with zinc methacrylate（ZDMA）showed similar excellent anti-aging effect.