Study On The Fabrication And Properties Ofepdm Reinforced By Sepiolite Mineral

Sepiolite is a porous magnesium-rich silicate mineral with a high aspect ratio,and its surface contains a large amount of silanol groups,which is an ideal reinforcing filler for ethylene propylene diene monomer?EPDM?.In this paper,the modified sepiolite/EPDM composite rubber was prepared by using the coupling agent KH570 modified sepiolite as the reinforcing filler via mechanical blending method.The organic modification process of sepiolite and its effect on EPDM performance were studied.The mechanism of modified sepiolite reinforcing EPDM was discussed,and the thermal kinetics of the composite rubber was analyzed by thermogravimetric-differential thermal analysis.The results show that the mechanical strength of peroxide vulcanizate is less than that of vulcanized rubber of sulfur system,but its thermal aging performance is better than that of sulfur system.The content of sepiolite,TAIC,PDM and S have significant effects on the thermal aging properties of the composite rubber.The mechanical properties of the composite rubber are superior when the dosage of KH570 is 6%of the mass of sepiolite in the sulfur vulcanization system.The tensile strength of the composite rubber increases first and then decreases with the increase of the modified sepiolite,which reaching a maximum of 16.17 MPa when the addition amount of modified sepiolite is 100 phr.Compared with the same amount of unmodified sepiolite-filled rubber,the tensile strength is increased by74.1%,which is 54.0%higher than that of the same amount of carbon black reinforced composite rubber.By fourier transform infrared spectroscopy analysis,it is found that the surface of sepiolite is grafted with C-H,C=C,-CH₂-and other functional groups,when the sepiolite powders are modified by the coupling agent.From the analysis of X-ray photoelectron spectroscopy,it can be seen that the electron-binding energy and half peak width of O1s and Si2p of modified sepiolite have greatly changed compared with unmodified sepiolite.The new absorption peaks of O1s photoelectron spectroscopy appear at 531.96 eV and533.53 eV,and Si2p photoelectron spectroscopy has a new absorption peak at 102.91 eV.The X-ray diffraction analysis shows that the crystal structure of sepiolite does not change significantly before and after modification,but the characteristic diffraction peak of sepiolite appear to be shifted to the left and the interplanar spacing increases after mixing.After vulcanization,the characteristic diffraction peaks appear to the right and the interplanar spacing becomes smaller.Those are caused by the strong mechanical squeezing force between the twin rolls during the mixing process and the chemical crosslinking of the rubber molecules in the sepiolite layer or in the holes during the vulcanization process.The apparent activation energy,oxidation induction time and reaction rate constant were obtained by means of oxidation reaction of the composite rubber vulcanizates and oxidation reaction kinetics calculation,which was compared with the experiment results on the condition of rubber aging oven.The results show that the oxidation induction time?t70?are in good agreement with the reaction rate constant K70,and the calculated results are consistent the experimental ones,indicating that the t70 could be applied to evaluate thermal oxidative stability of sepiolite/EPDM.