Study On Synthesis And Properties Of Liquid Fluorine-Containing Binder

Fluororubber has the advantages of high density,strong stability,good durability and high combustion energy with metal.It is a kind of special energetic material,which can be widely used as oxidant and binder in the field of aerospace propellant and polymer bonded explosive(PBX).However,due to the disadvantages of high processing temperature(higher than 150?),complex vulcanization process,fluororubber increases the processing difficulty of fluoropolymer matrix composite and affects its product performance.Therefore,the development of new liquid fluorine-containing binder is of great significance and value for the application of fluoropolymer in the field of explosives and propellants.In this paper,hexafluorobutyl acrylate(F6BA)was used as the main polymerization monomer,hydroxyethyl methacrylate(HEMA)as the cross-linking monomer,4,4'-azobis(4-cyanopentyl alcohol)(ACPO)and mercaptoethanol(ME)as the initiator and chain transfer agent respectively.A kind of liquid fluoroacrylate oligomer with low viscosity and good rheological properties was synthesized by free radical polymerization.Using infrared spectroscopy(FT-IR),Nuclear magnetic resonance spectroscopy(1H-NMR),carbon spectrum(13C-NMR),fluorine spectrum(19F-NMR)and gel permeation chromatography(GPC)were used to characterize the synthesized products.The viscosity of polymers was characterized and analyzed by means of rotational rheometer.The effects of initiator and chain transfer agent dosage and HEMA dosage on viscosity and conversion rate of polymer were studied systematically,and the best synthetic process was determined.Secondly,the fluoroelastomer was prepared by curing fluoroacrylate oligom er with isophorone diisocyanate(IPDI).The structure,thermal properties and mechanical properties of the elastomer were characterized and analyzed by FT-IR,DSC,TG and universal tensile testing machine.The influence of HEMA content on the thermal stability and mechanical properties of the elastomer was discussed.The dielectric resistance and filler dispersion of the elastomer were explored.The results show that the mechanical properties and thermal stability of the elastomer increase with the increase of HEMA content,and the elastomer has excellent medium resistance and filler dispersion.Finally,the fluoroacrylate oligomer(F4300)was compounded with self-made hydroxy terminated fluororubber DF800 and DF2050 in different proportions to prepare the elastomer.GPC,FT-IR,TG,DSC and universal tensile testing machine were used to characterize the oligomer and elastomer.The dispersion of fillers in different composite systems was characterized.The results show that F4300/DF800 and F4300/DF2050 composite system have complementary advantages,and their comprehensive performance is better than that of single componen t system.The optimal ratio of F4300/DF800 and F4300/DF2050 is 75:25 and 25:75 respectively.