Preparation And Properties Of Silicon-fluorine Containing Polyurethane Prepolymer Modified Epoxy Resin

Epoxy resins(EP)are the most significant class of resins used in industrial production.Epoxy resins are widely used in various areas because of their high mechanical strength,outstanding adhesion to most surfaces and good chemical resistance.However,epoxy resins have high brittleness,poor impact strength and damping properties,which restrict the utility for further performance applications.In this paper,the creative approach to improve the toughness of epoxy resins is to combine fluorine-containing organic silicon with polyurethane to modify EP to obtain a better performance epoxy composite material.The toughness of epoxy resins is improved,and the mechanical properties do not fall and the heat resistance and damping performance can also be improved.The synthesis contains three steps.At first,1,3,5-Tris[(3,3,3-trifluoropropyl)methyl] cyclotrisiloxane(D3F)was open loop polymerized to form hydroxyl fluorosilicone oil which was further end-capped with(3-(2-aminoethylamino)propyl trimethoxysilane(SCA-603)to form amine-terminated fluorosilicone.Second,the isophorone diisocyanate(IPDI),polyether glycols and amino fluorosilicone oil reacted to obtain isocyanate group-terminated silicane and fluorine containing polyurethane prepolymer.Last,using prepolymer graft epoxy resins to obtain fluoralkylpolysiloxane polyurethane prepolymer modified epoxy resin(FSPUP/EP).The above reactions were characterized by FT-IR.Mechanical test indicates that the toughness of the epoxy resin with FSPUP modified is improved highly while other mechanical properties are also strengthened.The tensile strength,elongation at break and impact strength of FSPUP/EP increase with the increasing of the content of FSPUP.When the content of FSPUP is 15%,the tensile strength,elongation at break and impact strength reach the maximum value,which are 65.6 MPa,11.4% and 13.1 KJ/m2,respectively.Compared with pure EP,the tensile strength,elongation at break and impact strength have increased by 17.8%,86.9%,29.7%.TG-DSC tests shows the thermostability of FSPUP/EP is greatly improved compared the pure EP.The glass-transition temperature decreases with the increasing of the content of FSPUP.Different content of FSPUP do not change the thermal degradation mechanism of FSPUP/EP.Dynamic mechanical thermal analysis(DMA)test shows,when the content of FSPUP increases,tan?max increases,the temperature range of tan? > 0.3 expanded and internal friction peak shifts to lower temperature.When the content of FSPUP is 15%,the damping properties reach the maximum value.Tan?max is 0.87,and the temperature range of tan? > 0.3 is 30.9?.Test frequency increases lead to changes in peak shifts to a higher temperature and tan? > 0.3 temperature range widened.