Study On The Solvent Resistance Mechanism Of HNBR/EPDM Blends

With the more extensive application of rubber blends in practical production,the study on the mechanism of solvent resistance of blends has important scientific and theoretical significance for its practical application.This paper is mainly to research the solvent resistance mechanism of Hydrogenated Nitrile Butadiene Rubber（HNBR）/Ethylene Propylene Diene Monomer（EPDM）blends.Firstly,the basic properties including vulcanization properties,tensile properties,and dynamic mechanical properties of HNBR/EPDM blends with eleven different blending ratios were studied.It was found that the compatibility between HNBR and EPDM was poor,but the co-vulcanization properties was well.The tensile strength and elongation at break of HNBR/EPDM blends increased with the increase of HNBR content,while the tensile stress decreased gradually.Secondly,the maximum swelling ratio of HNBR/EPDM blend in 28 different solvents was tested,and the Hildebrand solubility parameters and Hansen solubility parameters of HNBR/EPDM blends were obtained by fitting with Hansen Solubility Parameter in Practice software.The linear superposition equation of solubility parameters was obtained.The Flory-Huggins interaction parameters(χ_1D andχ_3D)between the HNBR/EPDM blends and solvents were calculated based on Hildebrand and Hansen solubility parameters respectively.The prediction ability of the two interaction parameters to the swelling behavior of HNBR/EPDM blend was compared.It was found thatχ_3D has stronger prediction ability and wider application range.Thirdly,the transport coefficients of many kinds of ester solvents,amine solvents and aromatic solvents in HNBR/EPDM blends were calculated.It was found that the sorption and permeation coefficient of solvent molecules had a two-stage linear relationship with the mass fraction of HNBR.The structure of solvent molecules had an important effect on their transport.The more complex the molecular structure,the more difficult it was for solvents to transport.In addition,the prediction ability ofχ_1D andχ_3Dto the transport behavior of solvent molecules was compared,andχ_3D showed stronger prediction ability.Finally,the effects of carbon black N220 and carbon black N990 on the solvent resistance of HNBR/EPDM blends were studied.It was found that the addition of fillers enhanced the solvent resistance of HNBR/EPDM blends.N220 had a stronger improvement effect because of its smaller particle size and higher specific surface area.The effect of immersion time in aviation hydraulic oil YH-15 on the physical and mechanical properties of HNBR/EPDM was studied.It was found that the tensile strength of HNBR/EPDM blend decreased rapidly at first and then tended to balance with the extension of immersion time,and the Modulus at 100%decreased at first and then increased.