The Synthesis, Vulcanization And Modification Of Fluorinated Polysiloxanes

Silicone is a kind of high and low temperature resistance,excellent weatherability,aging resistance of the polymer with a wide range of applications.Organic fluorine polymer has good resistance to saturated vapor,oil resistance and solvent resistance.Fluorinated polysiloxane with excellent comprehensive properties of both,can be widely used in aerospace,automotive and other fields.This paper uses Octamethylcyclotetrasiloxaneandmethyl(trifluoropropyl)cyclotrisiloxane in the presence ofa,ω-bis(tetramethyl ammonium)polydimethylsiloxane for ring opening polymerization,and to synthesize the fluorinated polysiloxane with excellent comprehensive performance successfully,and do in-depth research for the synthesis,vulcanization and modification.The main work was as follows:1.the fluorinated polysiloxane was synthesized successfully by anionic ring opening polymerizationwith the Octamethylcyclotetrasiloxane,methyl(trifluoropropyl)cyclotrisiloxane in thea,co-bis(tetramethyl ammonium)polydimethylsiloxane(TMACa)catalyst,and characterized by FTIR,1H-NMR.Thenwe explored the types and concentration of initiator,reaction time,capping agent and postprocessing factors on the impact of the experiment to determine the best conditions of the reaction,th last reaction conditions were:(1)usinga,ω-bis(tetramethyl ammonium)polydimethylsiloxane(TMACa),the concentration was 0.0025%～0.005%(2)the reaction time is 140min(3)the molecular weight terminated agent can be controlledby the quantities of terminated agent(4)were extracted by isopropanol postprocessing,the extraction times is three.2.Using the hydroxyl terminated fluorinated polysiloxane as base gum with the modified fumed silica filler,curing agent,TEOS and Dibutyltin dilaurate to prepare the containing fluorosilicone rubber at room vulcanization.Then we explored the effect of the quantiies of fumed silica and TEOS on the mechanical properties of rubber,performance the amount of heat and acetate,and also studied the effect of the fluorine content on tack-free time,aging resistance,oil and solvent resistance and thermal stability of the rubber.The experimental results show that the effects of fumed silica and TEOS on the mechanical properties of rubber are similar.With the increase of the dosage,the elongation at break decreased and the hardness increased,while the tensile strength increased first and then decreased.In addition,with the increase of fluorine content in the fluorinated polysiloxane,the drying time was extended,the aging resistance,oil resisitance and solvent resistance were improved,and the thermal stability became worse.3.Using the hydroxyl terminated fluorinated polysiloxane as the modifier,Dibutyltin dilaurate as the catalyst,ethyl acetate as solvent to synthesized the fluorinated polysiloxane modified epoxy resin polymer.It was proved successfully synthesized fluorinated polysiloxane modified epoxy resin polymer by FTIR and 1H-NMR to characterize its chemical structure.At last,the mechanical properties,surface properties and thermal properties of the modified polymers were studied.The experimental results show that the introduction of fluorinated polysiloxane will reduce the tensile strength and bending strength of epoxy resin,but the elongation increases;can enhance the hydrophobic properties of epoxy resin will strengthen;thermal stability;reduced glass transition temperature.