Study On The Sythesis Of Dihydroxydibenzo-18-crown-6and Its Application In Fluoroelastomer

Fluoroelastomer(FPM) is a sort of special synthetic elastomer including fluorine element on the backbone or branch of the molecule, which owns more excellent properties such as high-temperature resistance, chemical solvents resistance, oil-resistance and weather-resistance than other rubbers. FPM is applied in many crucial fields, such as seal, aerospace, military, petroleum, chemical industry, and automotive applications. The special chemical structure of fluoroelastomer leads to some limitated properties, such as bad low-temperature resistance, poor process property and low elasticity. One of the key problems that is imperious need to be solved is to improve the limitations of FPM while keeping its excellent properties to make it adapt to the widely application of FPM.PHACM which is prepared by graft modifying Bisphenol AF on the ACM can co-vulcanizate with FPM to prepare blends with excellent properties. Blends not only own fine mechanical property, but also keep excellent properties including high-temperature resistance, chemical solvents resistance, oil-resistance of FPM. However the relative poor compression set of ACM leads to poor compression set of blends.The crown18-C-6was added into FPM as functional additive to study the influence of crown18-C-6on FPM/PHACM blends, especially on aspect of compression set. It is found that the addition of crown18-C-6significantly shorten co-vulcanization time of blends at the same time keep the scorch time, and the tensile strength,100%stretching stress and tearing property of blends enhanced. The crosslink density enhanced, improving compression set and compression stress relaxation property of blends. The FTIR spectrums and DSC showed that the increasing of crosslink density is because of complexation between crown18-C-6and ether bond of PHACM. At the same time, crown18-C-6can complexation with CaF2which generated on the process of co-vulcaniation to formate stable complex compound.The dihydroxyl dibenzo-18-C-6(DBC) containing phenolic hydroxyl structure was prepared and characterized. The influence of dihydroxyl dibenzo-18-C-6on FPM and FPM/PHACM blends was studied. DBC can not only accelerate vulcanization of blends, but also treat as vulcanizating agent to enhance crosslink density and comprehensive properties of blends and improve crosslink structure, at the same time absorbing byproduct on the process of vulcanization. It is found that when DBC is1.4phr the comprehensive properties of FPM is best and blends show excellent properties including tensile strength from12.61MPa to14.96MPa, tearing strength from25.32MPa to29.35MPa and compression set from35.47%to30.26%. The addition of DBC can not only involve in vulcanicate reaction of FPM, but also complexs with ether bond of PHACM and perfect the crosslink network of blends.