Research On The Performance And Modification Of Trifunctional Cyanate Ester Resin

The cyanate ester resins is an important thermosetting resin in the fields of aerospace,electronics,architecture and military,etc because of its excellent high temperature resistance,dielectric properties,corrosion resistance,mechanical properties and processing properties.The bisphenol A cyanate ester(BADCy)is the most widely used cyanate ester resin at present,but its operating temperature is lower than 300 ?,which limits the further development of BADCy in the aerospace and other fields.The cured novolac cyanate ester resin(NCy)shows an excellent heat resistance and high glass transition temperature(Tg> 350 ?)due to its large amount of-OCN groups in its structure.However,due to the steric effect and high crosslinking density of the novolac cyanate ester resin,it needs a high post curing temperature for complete curing,and the brittleness is large(bending strength is lower than 80MPa),which limits the application range of the novolac cyanate ester resin.In this paper,the curing characteristics of two kinds of cyanate ester resins with three functional groups were studied,and the curing characteristic temperature,the thermal properties,dielectric properties,mechanical properties and water absorption of the cured cyanate ester resins with three functional groups were investigated.And the properties of the copolymers formed by two kinds of cyanate ester resins with three functional groups and BADCy were studied.1.The molecular structures of the triphenol A cyanate ester resin(TACy)before and after the curing were characterized by FT-IR.The curing process,glass transition temperature,heat resistance and dielectric properties of TACy were studied by DSC,DMA and TGA.The results show that the TACy has a higher activity than the BADCy does without adding catalyst.Under the same curing conditions,TACy shows a higher curing degree than the novolac cyanate ester resin(NCy)does.The glass transition temperature of TACy is 367?,with a very low and stable dielectric constant(less than 3)and dielectric loss tangent(less than 0.009)in the range of 2~18GHz.2.The curing characteristic temperature,thermal properties and dielectric properties of the 4,4,4-cyano-trimethylene(TMCy)were studied by DSC,DMA,TGA and dielectric test.The TMCy shows a high glass transition temperature(335 ?),a good thermal stability,a low dielectric constant and dielectric loss tangent.3.The copolymerization between BADCy and TACy in different proportions was carried out,and the properties of the copolymerized resin system were analyzed.The results show that the glass transition temperature decreases with the increase of BADCy content.The bending strength and tensile strength of the copolymer system increases with the addition of BADCy.When the amount of BADCy is 80%,the mechanical properties of the copolymer are the best,and the bending strength is 110% higher than that of TACy.Moreover,the copolymerized resin has good dielectric properties.4.The BADCy and TMCy were copolymerized in different proportions,and the thermal,mechanical and dielectric properties of the copolymers were tested.The results show that the glass transition temperature of the copolymer decreases with the addition of BADCy,and the toughness of the copolymer improves with the addition of BADCy.When the amount of BADCy is 80%,the resin has better mechanical properties,and its bending strength is 85% higher than that of TMCy and its dielectric constant is lower(less than 3.1).