| Fluororubber commonly was used as a sealing material of the aeronautical oil seal environment,thus,it contacted with oil medium for a long-term,the physical and chemical properties of fluororubber were easy to decrease and the sealing performance reduced.Therefore,it was significant to improve the medium resistance and prolong the service life of fluororubber.In this study polytetrafluoroethylene(PTFE)film was coated on the surface of the fluororubber to improve the rubber?s medium resistance in the high temperature,because the PTFE film had excellent high temperature resistance and medium resistance.but the surface adhesion of both PTFE and fluororubber were poor,It was necessary to improve their surface adhesivity through appropriate modification methods,therefore,in this study surface modification of fluororubber was firstly carried out by cold plasma treatment and sodium naphthalene solution,so as to improve the surface adhesion of fluororubber.The high temperature adhesive was then used to bond the PTFE film with the fluororubber at a high temperature to form fluororubber coated by PTFE film.The coated fluororubber and fluororubber samples were placed in the 150 °C oven for high temperature aviation kerosene,aviation lubricating oil,and hot air medium experiments.the tensile fracture morphology,surface elements,thermal properties as well as physical and tensile properties were characterized and tested.Finally,the life span of rubber was predicted by the evaluation index of elongation at break,so as to evaluated the effect of modification.After the surface of the fluororubber was treated by cold plasma,the inorganic filler of the rubber surface reduced,and it had obvious etching effect,the active O element content increased,while the inert F element content decreased on the surface of the fluororubber,at the treatment process(Ar,100 W,20 Pa,1 min),the rubber surface had good wettability,the bonding strength between fluororubber and PTFE was increased from 561 N/m to 605 N/m.However,the rubber was treated by the sodium naphthalene solution,the surface of the rubber had micro cracks,the bonding strength between fluororubber and PTFE was up to 2 637 N/m,the modification effect was significant,but the rubber matrix property was affected,for instance the mechanical properties reduced by 29.3%.After the aging test of high temperature medium,the tensile fracture morphology showed that there were many holes in the non-coated fluorine rubber samples,and the fracture of the non-coated fluororubber changed from ductile fracture to brittle fracture,while the coated fluororubber still remained ductile fracture.The results of both the dynamic mechanical performance and thermogravimetric analysis showed that the springback and the thermal stability of the coated fluororubber were slightly better than the fluororubber.The mass,size and hardness of the coated fluororubber have little change,while the non-coated fluororubber increased obviously.Compared with the fluorinerubber,the coated fluororubber decreased slightly lesser for the tensile properties.The comprehensive analysis results showed that the impact degree of medium affecting rubber?s properties from severe to tiny was the aviation kerosene bigger than the aviation lubricating oil,and the aviation lubricating oil bigger than the hot air medium in the three high temperature medium experiments.Taking the elongation at break as an life evaluation index,the life of rubber was predicted by linear equation,the results showed that the service life of the coated fluororubber in high temperature aviation kerosene,aviation lubricating oil and hot air was 622 days,667 days,674 days in turn,the service life of the fluororubber was 261 days,276 days,310 days in turn.The service life of the coated fluororubber was obviously higher than that of the fluororubber,it indicated that the coated fluororubber prepared in this study was effective to improve the high temperature medium resistance of fluororubber. |
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