| Carbon nanotubes(CNTs)exhibit excellent mechanical properties,such as the super high tensile strength,high specific surface area and high aspect ratio.CNTs can be considered as an ideal reinforcement additive for advanced composites.But several principle problems have not been got over by now.Consequently,exploring other effective dispersing method is still one of the key problems for fabricating high performance CNTs/polymer composites.In this paper,multiwalled carbon nanotubes(MWCNTs)/epoxy resin composites have been prepared by cast molding method.The MWCNTs were firstly surface functionalized and the effects of surface functionalized on the dispersion of MWNTs in epoxy resin and the properties of the composites were studied.The evolution on mechanical properties of CF/EP composites,CF/MWNTs/EP composites,CF/a-MWNTs/EP composites and CF/Triethylene-tetramine(TETA)-MWNTs/EP composites after enduring different environments.In this paper,bisphenol A epoxy resin was regarded as the research object.MWCNTs were chemically modified by a 3:1 mixture of concentrated mixture of sulfur acid/nitric acid.The original MWNTs,a-MWNTs and TETA-MWNTs were added into epoxy resin according to the content of 0.25wt%,0.5wt%,0.75wt% and 1wt% respectively.The tensile strengths and impact strengths of them were studied.MWNTs/epoxy resin composites were fabricated using ultra-sonication method.The characterization of the dispersion of MWNTs was observed by TEM method.The structures of the composites were characterized by spectroscopy.Fracture morphology was analyzed by SEM method.There are four kinds of hygrothermal environment which including 90 °C / 50 % RH,90 °C / 75 % RH,90 °C / 100 % RH and 60 °C / 100 % RH.The high temperature is set at 130°C.The effects of aging on the structures of four kinds of composites were analyzed.TEM test results show that the modified MWNTs can improve the dispersibility and solubility in epoxy resin.The properties of epoxy resin with MWNTs were better than that of pure epoxy resin.When the content of modified MWNTs was 0.75wt%,the mechanical properties of the three kinds of modified epoxy resin were the best,especially that of TETA-MWNTs/EP.FTIR results show that the carboxyl group and TETA have been grafted onto the surface of MWNTs.SEM photos show that the toughnesses of aMWNTs/EP and TETA-MWNTs/EP composites have been improved.The mechanical properties of all MWNTs/EP/CF composites have been reduced after hygrothermal environment and high temperature.And the retention rate of strength of TETA-MWNTs/EP/CF composite was the highest.The impact damage area of composites is greater after aging.In addition,there was no obvious effect of hygrothermal environment and high temperature on composites,which illustrated that it didn't happen any chemical changes on the materials. |
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