It Can Be Applied To The Preparation And Performance Research Of Modified Cyanate Ester Resin In Ultra-low Temperature Environment

With the increasing competition in deep space exploration,higher requirements have been proposed for the materials used in some special structural parts of space vehicle,such as the light-weight and resistance to hot-low temperature shocks.General epoxy resin matrix composites in aircraft structures graduallycannot satisfy the more stringent use requirements;therefore it is very necessary to develop a kind of polymer and corresponding composite materials,which can be applied at the ultra-low temperature.This paper mainly studies on the following aspects:Firstly,the epoxy resin?EP?and phenoxy resin?PK?was applied to modify cyanate ester?CE?resin,and a novel modified cyanate ester resin?CEPK?was prepared.The properties of CEPK were determined by means of differential scanning calorimetry?DSC?,mechanical properties testing,scanning electron microscopy?SEM?and thermogravimetry?TG?.The results show that the curing exothermic temperature of CEPK is reduced.CEPK10 resin modified by 10%?wt?PW can reach good mechanical properties which tensile strength is 78.6 MPa at-196?.The CEPK resin has a good thermal stability,and the retention rate of tensile strengthisabove 85%at 150?.The cracks were not observed on the surface of cured samples after 14 cycles?-196²00??.Secondly,the core-shell particles PW and block copolymer MN was introduced into the modified CE/EP resin,and the CEPW matrix resin and CEMN matrix resin were obtained.The heat resistance,mechanical properties,and micro-morphologies of the cured samples of CEPW and CEMN were investigated.The results show that the PW has little effect on the curing exothermic temperature.The mechanical strength of the modified cyanate ester increases firstly and then decreases with the increasing amount of PW.Impact strength of CEPW₅ is 12.3 KJ/m²at-196?It is increased by195%than impact strength of CE/EP.CEPW istoughened with PW by dispersing its own particles.PW has some influence on the pyrolysis temperature of CEPW;CEMN was toughened with MN by mean of phase separation,showing the same mechanical strength tendency as CEPW.The MN canreduce the pyrolysis temperature of CEMN resin obviously when the amount was over 10%?wt?.The cyanate ester resin modified by 10%?wt?MN obtainesgood high-low temperature shock resistance,andthe CEMN₁₀has no cracks on the surface after 30 cycles?-196²00??Finally,CEPK₁₀resin and carbon fiber were selected to fabricate CEPK₁₀/carbon fiber composites.The technological parameters of CEPK₁₀ resin/carbon fiber composite were investigated.The mechanical properties of the CEPK₁₀/carbon fiber composite at different temperatures and its adaptability to temperature field changes were measured.The results showe that the viscosity of CEPK₁₀ matrix resin is lower than 10 pas at 90?¹50?and the low viscosity maintain above 30 min at 120?,which means it has a long processing time.At room temperature,the tensile strength was 731.3 MPa,the flexural strength is 885.3 MPa and the interlaminar shear strengthis 75.3 MPa.At low temperature,the tensile strength of CEPK₁₀/carbon fiber composites decrease firstly and then increase with the temperature declined.The minimum value of tensile strength is discovered at-100?,which has declined by 22%than that at room temperature.The CEPK₁₀/carbon fiber composites were not significantly damaged by being immersed in liquid nitrogen for 15 days,and its tensile strength have declinedby 5%after 40cycles?-196²00??.