| Compared with me tal ma terials, carbon fiber reinforced epoxy resin matri x composite material has hi gh specific strength, hi gh specific mod ulus, corrosio n resistance, fatigue resistance and good structure stability and other advantages, which has been widely used not only in military and aerospace fields, but also has made big progress and outstanding achieveme nts in the civilian aspects i n recent years.The curing process of resin matrix was determined b y 110℃/2h+140℃/2h+160℃/3h based on analysis of the results of gelation ti me and DSC with various heating rates. The n it was mixed with the short carbo n fiber to prepare for the advanced carbon fiber reinforced epoxy resin matri x composites which has made higher mechanical properties and heat resistance as well as excellent processing properties. The effects of different carbon fiber length and content on mecha nical properties, storage modul us and glass transition te mperature of the composites were studied. The results showed that: when the carbon fiber length was 3mm, the content reached 0.25%, the mec hanical properties of the co mposite were best, the te nsile strength, i mpact toughness, flexural strength a nd flexural modul us respectively has increased b y 14.2%, 25.3%, 30.3% and 68.9% tha n the pure resin matrix; a nd the glass transition te mperature has increased about 6 ℃ tha n the pure resin matrix, whic h indicated the best heat resistance of the co mposite; besides,the storage mod ulus of the composites were higher tha n that of the pure resin matrix, which has made the maxi mum storage modul us up to 31.8%,when the carbon when fiber conte nt reached 0.35%.Based on the optimization length and conte nt of short carbon fiber, the carbon fiber surface was treated with disper sant F-38(propylene gl ycol bloc k polyether). Influence of dispersant on the curing reaction and dispersing age nt content on co mposite material mec hanical performa nce and heat resistance performa nce were studied, as well as the dispersion of the carbon fib ers in the epoxy resin matrix was discussed. The results showed that dispersing has no t participated the syste m curing reaction, but reduced the ther mal properties and mec hanical properties of the co mposite; when the dispersing age nt content was 2.5%, the tensile strength has made the small cha nge, only reduced by 4.63%, and the carbon fiber reunion was also reduced significantly by addition of the dispersant.Finally, carbon fiber surface was treated by nitric acid and silane couplin g agent, effects of nitric acid treatment ti me and dosage of coupling age nt o n the properties of co mposite were studied, the results showed that: whe n the oxidation ti me was 5h, the conte nt of co upling age nt reached 2%, the mec hanical properties of the composite made big cha nges, the tensile strengt h increased by 28.19%, the flexural strength increased by16.21%, the i mpact toughness decreased by 36.43% on the opposite; in addition, the loss peak of the composite was mi nimum, i ndicating the best interface of the composite; the glass transition temperature was increased by about 5℃, which indicated tha t the heat resistance of the co mposite was the best... |
PDF Full Text Request