| There are various epoxy curing agent,and aliphatic amine predominates in the field of rapid solidification.Aliphatic amines contain highly active hydrogens,which are strong nucleophilic reagents,can open the epoxy groups of epoxy resin and make it gel and cure in a short time.But their shortcomings of effumability,large brittleness,poor resistance to impact,weatherability and toxic action restrict their usability,therefore,to meet market demands,amine curing agents must be modified to abtain modified amine curing agents which possess low volatility,good toughness,good weatherability,non-toxic or low toxic and can cure at room temperature or lower temperature.Cardanol(CA),the natural cashew shell oil extraction,was used to replace phenol to carry on phenolic modification for triethylene tetramine(TETA)to synthesise a broad spectrum phenolic aldehde-amine curing agent(PCT)for epoxy resin.Besides,its optimum synthesis conditions,product stability,structure characteristics,cured thermo-gravimetric(TG)analysis,impact resistance,corrosion resistance and application in the preparation of epoxy foams were studied.The main research contents and conclusions are as follows:(1)PCT curing agent was synthesized by mannich reaction principle with CA,formaldehyde(FA)and TETA.And the optimum technological conditions for synthesis were elected by using the orthogonal experiment design and single factor experiments as follows:the molar ratios CA to PA to TETA is 1:0.8:1.4,reaction temperature is 90℃,reaction time is 100min.Through infrared spectrum analysis shows that cardanol of hydroxyl methyltion not on=ly have condensation reaction but also a certain degree of ortho substitution reaction,and the location of the polymerization reaction is ortho substitution reaction of phenol hydroxyl rather than the double bond in the side chain.Besides,phenolic hydroxyl also have a condensation reaction with the amidogen of TETA to some degree.After 1d,3d,7d,30d stability tests showed that PCT possessesd a good stability.TG analysis showed that the epoxy cured by PCT increased initial weight loss temperature from 212.9℃ to 287.4℃ and the temperature at maximum rate of weight loss from 272.7℃ to 364.4℃,the thermal stability improved obviously and superior to the epoxy’ thermal stability cured by T-31.Impact resistance tests showed that the epoxy’ impact strength increased from 4.34J/cm2 to 18.28J/cm2,toughness got obvious improvement and higher than 9.05 J/cm2 of the epoxy’ impact strength cured by T-31.After 48h of corrosion resistance tests of 10%NaOH、10%H2SO4、10%NaCl solutions showed that the epoxy’ corrosion stability had been obviously improved,and resistance to alkali corrosion was superior to acid corrosion.(2)A new type of epoxy foam was prepared with bisphenol A type epoxy resin(E-51),n-pentane(N-PT),tween-80/silicone oil and PCT.Also,the single factor experiment was studied to find the effects of consumption of N-PT,tween-80/silicone oil and PCT on the foams’ per formance.The results showed that foams’ indicators,such as waterproofness and heat insulation property,stayed to get good than gradually became worse.Ultimately,a conclution that the best formula of preparation of new type epoxy foam is abtained as follows:100 E-51、30 PCT、5 N-PT、5(tween-80/silicone oil),the optimum process is that E-51,PCT and tween-80/silicone oil are mixed and stirred firstly,than N-PT is added,continuing to stir 2min,pouring,foaming and molding.The foam’ main performance indicators as follows:density 0.04667g/cm3,bibulous rate 2.91%,thermal conductivity0.037w/(m.k),compressive strength 276KPa,and initial weightlessness temperature and the temperature at fastest weightlessness rate are 248.4℃ and 362.3℃,respectively.(3)Expandable graphite(EG)was added to foam to carry on flame retardant modification,and the effects of EG’ consumption on the flame retardant property,heat-conducting property,mechanical property,thermal property,physical property were sudied.The results shows that adding a small amount of EG can improve the quality of bubble holes of foam,but bubble holes will worsen with the increasing of EG’ adding amount.When the EG’ consumption is 30%,the modified foam’ performance indicators as follows:density 0.07615g/cm3,bibulous rate 2.56%,thermal conductivity 0.043w/m.k,compressive strength 398KPa,initial weightlessness temper-ature and the temperature at fastest weightlessness rate are 43.5℃ and 351.5℃ respectively,and oxygen index 37. |
